I have a Simaudio Moon 110LP phone preamp amplifying a Dynavector 20X2L cartridge on a VPI Classic. It feeds in to an Outlaw Audio RR2160 amp which drives Magnepan LRS speakers.
I recently moved and two months in I realized my speaker placement wasn’t quite right, so today I reorganized my listening room. This involved unplugging some power cables but I kept most of the interconnects in place. I did have to disconnect the phone stage from the amplifier.
After getting things back into place, I listened to some music using coaxial input before reconnecting the interconnects of the phono stage. When I tried to, I actually got some electric current that burned my hand slightly. This came from the back of the amplifier. I made sure everything was unplugged and tried again - this time a spark and smoke from the interconnect making contact to the back of the amplifier.
I’m so confused why this would happen, but eventually I did get everything connected. Now the output from the phono stage is just a bump every 1 second. It doesn’t amplify the signal from the TT.
My amplifier has a built in phono stage and using this I was able to verify that the turntable is still producing a signal. The built in phono stage sounds terrible, however, as thin and flat as paper. It is music, however.
When I connect the phono stage to the power, the blue light on the front illuminates for a moment and then goes dark.
Incredibly, when I was unplugging the phono preamp, I actually got some current from simply touching the exterior of the box. Something is seriously wrong and dangerous with my setup, and this box was grounded to the turntable with a ground cable, which was connected to the outlet with a three prong cable with ground.
Has anyone experienced anything like this before? I will email Simaudio and see if they’ll repair it. I’m also taking recommendations for replacements. I liked the 110LP and maybe will just replace with the 110LPV2.
To get a spark as well as an electrical shock there had to be a difference of potential, voltage, of a least around 40V to 50V measured between the two points you received the electrical shock. I assume all the equipment is plugged into a single duplex outlet fed from a single circuit breaker in the electrical panel.
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Simaudio Moon 110LP phono preamp. Factory plug in power supply is two blade, no safety ground pin. I assume the power supply is the original.
Outlaw Audio RR2160 amp has only a two prong power inlet connector. No safety ground prong. Unit has the Double D symbol logo on the unit indicating the 120Vac power wiring is double insulated. Chances of a hot bared conductor to chassis fault? Slim to to none.
VPI Classic. Has a 3 prong inlet connector. Safety equipment ground is used.
I wouldn’t think the tone arm would be connected to the AC mains safety equipment ground.
Do you have a multimeter you can use to check for continuity/resistance, as well for voltages? If not buy a descent one. You can pick a descent one for around $50.00.
Incredibly, when I was unplugging the phono preamp, I actually got some current from simply touching the exterior of the box.
To receive the electrical shock your body had to have a point of entry and a point of exist. Can you recall what two metal objects you were contacting at the same time? One was the metal case of the 24Vdc fed phono preamp. I assume the plug in power supply (output 24Vdc) for the the phono preamp is plastic. Is the wall duplex outlet cover plate plastic?
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and this box was grounded to the turntable with a ground cable, which was connected to the outlet with a three prong cable with ground.
That doesn't sound right. The phono preamp should be grounded to the tone arm, not to the wall AC mains safety equipment ground...
Using a multimeter, this could easily be verified.
The OP should first locate the problem. Was it the phono preamp power supply that caused the problem?
Or was it x or y or z that caused the problem that damaged the phono preamp?
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FYI, in older homes with old two wire branch circuit wiring, a plug-in circuit tester works good for finding reversed AC polarity. They will tell you if there is an OPEN GROUND. What they don’t tell you if the tester says OK is the EGC (Equipment Grounding Conductor) really an EGC that runs back to the electrical panel or is it a Boot Leg EGC created by installing a jumper from the neutral terminal on a duplex receptacle to the EGC terminal screw on the outlet. It will also not tell you if the neutral conductor and EGC conductor are reversed on the outlet.
RR2160 amp has built in DAC and has two coax inputs. One to CD player one to bluesound node.
bluesound node
Internet provider line into your home? Fiber, Coax cable, other?
Are you using WiFi or hard wired Ethernet cable to the bluesound node ? IF hard wired is the cable used a shielded ethernet cable? (Looking for a possible ground path)
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(CDP digital out used as a transport)
Does the CDP use a grounded power cord?
yes you’re right the preamp was grounded to the tone arm.
IMO, that is the way it should be done. With multimeter you will verify the tone arm is not connected, grounded, to the TT EGC.
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Incredibly, when I was unplugging the phono preamp, I actually got some current from simply touching the exterior of the box.
I thought you meant unplugging the preamp power supply from the wall outlet you were touching the metal "box" of the preamp with the other hand. Thus my questioning about the wall outlet cover plate. If metal it would be grounded. I was looking for a possible difference of potential, voltage, from the phono preamp metal "box", to ground that caused the electrical shock.
You clarified with this.
you asked what two metal objects I was connecting. I was connecting the interconnects from preamp OUTPUT to the analog INPUT of the TT.
analog INPUT of the TT. ??? You mean analog input of the RR2160 amp?
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I had an idea which may be totally wrong but I noticed the blue light in the 110LP flickering the last couple months, and it’s connected to the circuit inside the preamp by a wire. Maybe something went wrong with that wire and it shorted to the exterior of the preamp box.
Don’t do any more experimenting using the phono preamp.
The normal operating input voltage of the phono preamp is 24Vdc. Power wise just a few watts. That normally will not cause sparks.
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From original OP:
After getting things back into place, I listened to some music using coaxial input before reconnecting the interconnects of the phono stage. When I tried to, I actually got some electric current that burned my hand slightly. This came from the back of the amplifier. I made sure everything was unplugged and tried again - this time a spark and smoke from the interconnect making contact to the back of the amplifier.
That would imply a significant difference of potential, voltage, between the two points.
Just a guess you had your fingers of one hand holding the outer ground shell of the interconnect and touched the rear metal panel of the RR2160 amp with the same hand. (In and out points were the finger(s) of the hand.)
Sparks? From the outer ground shell of the interconnect plug to the rear panel or outer ground shell of the RCA jack on the RR2160 amp, OR center pin of interconnect cable to RR2160 amp? (Hopefully you were not successful in plugging the interconnect into the Line in RCA jack of the RR2160 amp.)
Where is the difference of potential, Voltage, power, coming from? That is where the multi meter comes in. I will instruct you where to use the multimeter.
If you do not also buy a plug-in circuit checker I will instruct you, using the multimeter, how to preform the same tests as the circuit tester.
Using the multimeter we will verify the RR2160 amp does not have an internal Hot 120V to metal chassis fault. We will try to run tests on all the associated equipment until faulted culprit is found.
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I was going to just get a no contact voltmeter, but it seems maybe I should instead get a multimeter? Let me know what you would advise.
Multimeter...
As for checking the 120Vac wall outlet. A multimeter can preform the same tests as a plug-in circuit tester. Buy both if you want. If only buying one, buy a multimeter
it is actually the Southwire "10041N autoranging multimeter." I use it mostly for DC mA but occasionally I use it for checking continuity and less often for checking AC voltages.
It looks better. Also seems to have more user friendly features. Accuracy of AC voltage measurements??? It didn’t say it is a True RMS meter.
As for using the meter to check/set DC ma bias it is probably fine. Use the mA rotary switch setting. It should give a more accurate reading than using the 10 A setting.
Manual says 275 to 300 ma. My understanding that is too high.
My Son bought a V12 a few years ago at, I believe an Estate sale. He said he was having problems setting the bias. He brought it over for me to look at. I tested the KT88 power tubes in the amp. On the "Life Test" all tested good except two tested good marginal.
What didn't test good was the 4 small signal tubes. He bought 2 new 6922 tubes (input / driver tubes) and 2 SV83/EL84 tubes (Current source tubes).
While he was waiting for the new tubes he searched Cary chat forums on the Net. He found a good site that said the Cary manual bias settings were too high. I can't remember where we set the DC ma bias at. What ever it was he hasn't had any problems with the Amp. That is when he uses it...
Subwoofer? You keep adding equipment... Does the 120Vac IEC inlet connector on the back of the sub have three prongs? Therein an equipment ground prong? My bet is yes. Correct?
*** Does the CDP use a grounded power cord? Therein the IEC inlet on the back of the CDP has a third prong for the equipment from the wall outlet?
I have been looking for an equipment ground that is grounding the chassis and or signal ground of the RR2160 amp through the outer plug shell ground of an RCA interconnect. If the subwoofer uses the wall outlet equipment grounding that may be the ground. I assume the sub was plugged into the 120vac wall outlet.. It doesn’t matter if the sub is powered on or off. If the cord is connected at both ends the sub chassis is grounded...
The equipment ground was/is the fault circuit path back to the source. That is if the subwoofer chassis is connected to the wall outlet safety equipment ground.
That’s a pretty good size bite out of the outer shell of the RCA plug on the interconnect cable. I didn’t see its’ mate on the RR2160 amp. It has to be there somewhere.
Sometime later today, Friday the 28th, I will work up a testing procedure. It would go a lot quicker if we could respond back and forth Friday night.
To ensure safe operation and service of the meter, follow these instructions. Failure to observe these warnings can result in severe injury or death.
Page 5
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Warning or Caution
Read Instructions
To ensure safe operation and service of this meter, follow all warnings and instructions detailed in this manual.
Risk of Electrical Shock
Improper use of this meter can lead to risk of electrical shock. Follow all warnings and instructions detailed in this manual
page 6
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Pay close attention to pages 5 thru 14.
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For all the testing you will be preforming the test leads are plugged into the, black lead into the Com (Common) jack and the red lead plug into the red "VΩ" jack. ("VΩ", Volt / Ohm Jack) Page 7
DO NOT attempt to measure continuity on a live circuit.
Page 13.
DO NOT attempt to measure resistance on a live circuit.
Page 14
NEVER plug the red test probe lead plug into the "10A" jack or "mA/μA" jack when measuring voltages. LIVE circuits. See page 12.
That would create a dead short across the LIVE circuit.
Assuming the subwoofer uses the EGC, (Equipment Grounding Conductor) from the 120V wall outlet,
and assuming the sub amplifier’s circuit ground is connected to the chassis, (high probability),
and therefore the return signal ground in the RCA interconnect cable is connected to the signal ground of the RR2160 amp,
And therefore the circuit signal ground of the RR2160 amp is, (high probability), connected to the chassis, either directly or indirectly, the RR2160 amp is grounded to the 120Vac wall outlet EGC.
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Therefore, the first thing I want you to check is the output voltage of the plug-in SMPS Wall Wart) for the phono preamp.
You might want do the test on a kitchen counter top or a table.
mm meter.
Install the two test leads. Black lead in COM jack. Red lead in VΩ jack.
This test will, should, tell if the SMPS power supply has some kind of an internal fault that somehow is passing a high AC mains line voltage to the output of the power supply.
For the test you might want to use a factory OEM three wire grounding type power cord. The center offset ground IEC EGC ground contact will be used to hold the black lead probe tightly in the EGC ground contact. That will free up a hand...
Set the mm to V (volts). V is to the right side of OFF. mm will default to AC volts.
First check the wall receptacle outlet, you will be using, for the correct Hot / neutral AC polarity. At the same time you will be checking checking for an EGC ground.
Insert a test lead probe into each of the two straight slots contacts. You should measure 120Vac nominal.
FYI (If the duplex outlet is a 20A the neutral will have a "T" slot. If a 15A duplex receptacle the neutral contact will be the longer slot of the two parallel slots. Therein the Hot is the shorter of the two.
Next insert a test lead probe in the small slot Hot contact of the receptacle. Insert the other test probe in the ground hole. You may have to move the tip of the probe to one side or the other to make contact to the ground contact. You should measure, read, 120Vac nominal. The same voltage as you measured from Hot to neutral. This shows two things. The hot /neutral wiring AC polarity is correct and an EGC ground is present.
(FYI the reading could be slightly higher due to a loaded VD (Voltage Drop) on the hot and neutral circuit.)
One last test. Measure for voltage from the receptacle neutral contact to the ground contact. (Using a wall duplex receptacle I measured 1.4mV ac.
(Note. On a regular grounding type receptacle the center trim screw that holds on the outlet cover plate is also connected to the EGC ground. You can also use the screw head for the ground connection. Insert probe tip tightly against the straight recessed slot for the screwdriver to make a good electrical contact.)
FYI, use the same method above to check the two wall duplex receptacles that feed your audio system equipment, for the correct hot/neutral polarity and and the EGC is present.
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Finally, testing the plug-in SMPS.
Plug the OEM power cord into the wall 120Vac receptacle outlet. (Outlet has been checked, OK.)
Set the mm to V (volts). mm will default to AC volts.
OEM IEC power cord. Insert one test lead probe in one of the outside female contacts. Insert the other probe in the other outside female contact. You should read around 120Vac, nominal.
Insert one test lead lead probe in the center offset ground contact. Insert the other test probe in one of the outside female contacts.... From Ground to Hot contact you will measure 120Vac nominal.
Leave the test lead probe inserted in the ground contact of the IEC power cord.
Plug in the SMPS into the same duplex outlet as the OEM power cord.
Be careful, the outer sleeve contact of the SMPS power cord connector may be Hot voltage ground.
Next, depending on how much time has elapsed the MM may have to be shut off. Then turn mm selector switch back to "V" (Volts).
Next touch the other test lead probe to the outer sleeve contact of the SMPS output cord power connector. Does the mm meter display a AC voltage? How high of a voltage?
If you measure a high voltage you need to check it’s a real power voltage and not a false phantom voltage.
Remove test lead probe from the SMPS output cord connector. Turn mm selector switch to LoZ setting. (Last setting on right side of off.) Never change the selector switch with lead probes connected to a possible live voltage.)
Check for the high voltage again on the connector sleeve contact.
Also measure for a voltage to the center female contact of the power connector.
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If you did not read, measure, high voltage, or any voltage... Question... Is the SMPS 120Vac plug in blades the same width or is one wider than the other? Therein polarized. If both blades are the same reverse the SMPS 180 degrees in the receptacle and preform the test for high voltage again.
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If still there is no voltage readings, you should then check the output DC voltage of the SMPS to make sure it is working properly.
Remove test lead probe from the ground contact of OEM IEC power cord.
Test;
Set MM selector switch to "V" (volts)
Press the SEL button once to switch to DC volts. mm should display V DC.
Voltage test. 18Vdc female connector. Without touching the metal probes with your fingers... Touch, contact, the RED lead probe to the center female contact, of the power connector and touch the BLACK lead probe to the outer metal sleeve of the connector, both at the same time. You should read + 18Vdc nominal. If you do not read +18Vdc make sure you a making a good contact to the connector.
You can Also use the LoZ setting as well. Rotate the selector switch to LoZ. Press SEL button. mm should display V DC. Red lead probe to center contact. Black lead probe to outer sleeve contact on power connector.
FYI the outer sleeve electrical contact is B- negative of the DC power supply. It also should be circuit ground of the power supply and Phono preamp when connected to the preamp.
If it does not read +18Vdc? or the meter reading is + - + - + - + repeatedly 18V? Or maybe the mm is reading a higher voltage??? Note what you are seeing.
Hopefully you can understand my long above post. Looks like I should have proof read it a couple of times after posting it. I spotted a few double words here and there.
I corrected a couple of poorly worded sentences in my post above. Read through the Long post... I will check your thread occasionally tonight for any posted questions you may have.
I watched your video a couple of times again today. I can’t explain why the SMPS could pass an AC mains voltage to the phono preamp, You wouldn’t think it could... But, you said in the video you received an electrical shock touching the metal enclosure of the preamp. The power supply DC B-, and circuit signal ground, is connected to the preamp metal enclosure, directly or indirectly. If not the enclosure would act as an antenna.
i then unplugged the phono, connected it to TT via RCA Input on phono, plugged in again. Measured 49V with red lead on the shield of the interconnect plugged into the R input of the phono, which dropped to 0.14V on LoZ
I would NOT connect the input or output jacks of phono preamp to anything .
SMPS (one lead in ground of OEM ITC, the other on the sleeve contact of the SMPS):
48V on V
0.13V on LoZ
thoughts?
48V AC on V Might not be real power.
0.13V on LoZ real power .... ???
Thinking on this one.
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SMPS (red lead center, black on sleeve):
18.5V on B
0L and it beeps on LoZ
18.5Vdc on V correct?
0L and it beeps on LoZ. I may have read the instruction manual wrong. LoZ may only be for AC voltage.
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I can test the outlets where things are plugged in too.
Yes, check them.
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and to elaborate: yes I felt current on the enclosure of the preamp. I also felt current, I believe, on the enclosure of the amp at some point. And when I connected the tone arm ground cable to the amp ground (the amp has a built in phono stage), there was also a spark.
Was the SMPS unplugged from the 120Vac wall outlet or the power cable from the SMPS disconnected from the phono preamp? Preamp was dead?
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I believe current was flowing through the interconnects between phono preamp and amp,
Yes agree. But, my understanding is the SMPS was feeding power to the phono preamp at the time. Correct?
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But since all this I’ve listened to about 3 hours of music using the amp with no issues whatsoever (phono disconnected of course).
I think I messed up on the DC measurements, i think they were AC. so let me try again:
SMPS (one lead in ground of OEM ITC, the other on the sleeve contact of the SMPS):
0.6 mV DC on V
0.0 mV DC on LoZ
SMPS (red lead center, black on sleeve):
18.15 V DC on V
18 V DC on LoZ
SMPS (one lead in ground of the OEM IEC connector of the power cord , the other on the sleeve contact of the SMPS):
0.6 mV DC on V
0.0 mV DC on LoZ
Multi-meter should have been set to AC voltage not DC. I am looking for AC mains voltage on the SMPS output power cord connector. The measurements would be good if only AC measurements.
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SMPS (red lead center, black on sleeve):
18.15 V DC on V
18 V DC on LoZ
This is correct. Voltage looks good.
That doesn’t mean there is not a problem with the preamp. I believe there is. The Blue power light maybe saying there is.
Again, I would NOT connect the input or output of the preamp to any equipment.
Yes I verified your question about subwoofer in earlier comment today. The subwoofer pins are only two even though the power cord has three prongs. So I assume it’s ungrounded. But note the CDP is grounded and the amp is sitting on top of it and connected via coaxial cable.
Yes the sup amp is ungrounded. AC power wiring in the sub amplifier is double insulated.
So where was the spark fault current path? What is the source.
No doubt there is a difference of potential, voltage, between the output of the phono preamp and the RR2160 amp signal ground, (outer shell) of the analog input jacks.
Saturday, check for voltage from the outer shell of the output RCA jack of the phono preamp to the outer shell of the analog input RCA jack on the RR2160 amp.
Should of done that to begin with...
Both units powered on.
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I think we are back to square one.
When you get a chance check the wall outlets the equipment plugs into for proper Hot / Neutral polarity and for equipment ground. At least you will be able to check them off your list.
I could be wrong, ( the amp hasn’t been checked out yet) but I think the phono preamp is the problem.
I base that on this resent post from the OP.
But since all this I’ve listened to about 3 hours of music using the amp with no issues whatsoever (phono disconnected of course).
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He also posted the same thing earlier in the thread.
@jea48 RR2160 amp has built in DAC and has two coax inputs. One to CD player one to bluesound node. Since this episode I’ve been listening to music off the node without problems.
I don’t remember reading a post where you responded to this.
If you did not read, measure, high voltage, or any voltage... Question... Is the SMPS 120Vac plug in blades the same width or is one wider than the other? Therein polarized. If both blades are the same reverse the SMPS 180 degrees in the receptacle and perform the test for high voltage again.
That is from the long winding thread I posted yesterday.
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One other thing I didn’t think about yesterday. The tests for the SMPS I had you do for checking for AC mains high voltage on the output side of SMPS were unloaded.
I don’t know what I was thinking yesterday... I should of had you do the tests with the phono preamp connected to the SMPS. Therein the connected load. Likely a defective connected load that might be overloading the SMPS. A real world test...
Probably also should have had you use the wall outlet that the SMPS is normally plugged into. IF, one of the blades is not polarized, therein it could be plugged in either way, it would be plugged in the direction that caused the electrical spark fault event.
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IF you want to try the test again.
Test procedure is a little different than yesterday.
You will still use the OEM 3 wire power cord to connect one of the mm test lead probes to the wall EGC. ( an extension of the probe lead)
1) Set up for the test.
Before the SMPS output power cord connector is plugged into the phono preamp.
Connect an IC (interconnect cable) into one of the RCA output jacks on the preamp. Extend the other end of the IC so it will be easy for you to touch the other test lead probe of the mm to the outer ground shell of the IC RCA plug.
2) insert the mm black test lead probe into the female EGC ground contact of the plugged in OEM power cord.
3) Set mm to "V". (mm will default to V AC.)
4) Plug SMPS output power cord connector into phono preamp. (Blue light starts doing its’ thing. Preamp has DC power. SMPS has a load on its’ output)
5) Touch mm test lead probe to the outer ground shell of the IC RCA plug.
What voltage is measured, displayed, on the mm? No need to check for LoZ voltage. The connected load of the preamp is more than enough load. LoZ would only add a small additional load.
6) Check again for a voltage reading after the blue light on the front of the preamp is no longer lit for any difference of voltage measured.
7) Just to cover all the bases... Repeat the test measuring for DC voltage. You probably should let the phono preamp do a reset by disconnecting the SMPS power cord plug from the preamp. Just trying to cover all the bases.
I’m obviously leery of connecting them again but if there’s some way to do so safely I might be willing to try. Thanks for all your help.
NO, I wouldn't if it was my equipment.
I haven't mentioned it yet. You may have damaged the analog L & R input circuitry in the RR2160 amp. The pair of RCA jacks you plugged the ICs into from the phono preamp.
I haven't mentioned trying to connect a different source to any analog inputs on the amp as yet. You don't know yet what what is causing the problem.
I will go back to you previous post I was reading and respond to it.
Note... Inside heavy light gray line is me. Outside heavy light gray line is you.
Saturday, check for voltage from the outer shell of the output RCA jack of the phono preamp to the outer shell of the analog input RCA jack on the RR2160 amp.
Should of done that to begin with...
Both units powered on.
5.5Vac on V
0.02Vac on LoZ
My response:
Could you check again using the DC setting.
LoZ is not needed for either AC or DC in this case.
Question:
I didn't think about until just now. Was all associated audio equipment still plugged into the same 120Vac outlets? Especially the CDP? It doesn't need to be turned on, just plugged into the wall outlet. At present the CDP is the only piece of equipment the uses an EGC that is connected to the RR2160 amp with ICs.
Need to have everything connected the same way as the day you received an electrical shock and the spark event.
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jea48
When you get a chance check the wall outlets the equipment plugs into for proper Hot / Neutral polarity and for equipment ground. At least you will be able to check them off your list.
You
I sent a lot of messages last night so perhaps you missed:
You
I tested the outlets where things were plugged in. The hot/neutral is reversed. So the hot is the longer left slot, the neutral is the shorter slot on the right. The ground appears to be functioning.
My response:
Larger of the two slots is the neutral side of the receptacle. You measured 120Vac to EGC ground. (Hot black ungrounded conductor is connected to neutral terminal)
Smaller slot is the Hot side of the receptacle. You measured zero nominal volts to EGC ground. The white color "Grounded Conductor", "White neutral conductor", is connected to the Hot terminal of the receptacle.
Yes, the branch circuit wiring, Hot and neutral conductors are reversed (wire wrong) on the duplex outlet.
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You
Explicitly, this means when I’m on V or LoZ and I go into hot/neutral I get 120Vac. When I go neutral/ground I get close to zero, and when I go neutral/hot I get ~120Vac. However, hot/neutral is reversed.
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You're starting to sound like me late last night...
However, hot/neutral is reversed.
On that I agree.
i don’t think it matters but when I plug one lead of MM into ECG and the other isn’t connected to anything I get 5V on V but it disappears of course on LoZ.
Well.... Though the Audio system equipment probably has been in use, operating Ok plugged into wall outlets with the Hot and neutral branch circuit conductors reversed, wired wrong, For now I think we can over look it. But with that said it needs to be corrected.
Question... Are you renting or do you own the residence? Is the electrical panel located in the dwelling? Are the wall outlets on opposite sides of the room on the same breaker in the electrical panel. Roughly how old would you say the building, electrical wiring might be?
I realize the electrical wiring issue is off tract at the present. At some point, after we figure out the problem with your audio system we will come back to it.
his wouldn’t be a big deal if the three other RCA inputs still worked. Last weekend I connected the preamp to analog input 4 on the amp and it made the same soft bump sound. I just remembered the blue sound node also has an integrated DAC and RCA out. So if I don’t mind risking frying it I could try connecting it. Ideally I should find something cheaper, maybe my TV (which is old and I don’t use). I’ll check if it has RCA out when I get home.
Before you do anything run a quick test on the RR2160 amp. Need everything associated with the audio system plugged into the120V wall outlets as they were the day of the spark event. Need all ICs connected, except the ICs of the phono preamp, to the RR2160 amp.
Test:
I want you to measure from an analog RCA jack input (that you have not connected the phono preamp to) outer signal ground shell to the wall outlet EGC.
Problem may be you can't unplug any audio equipment from a wall outlet to use the power cord for a test lead extension. You could use a 3 wire grounding type drop cord and use the EGC from it. Just make sure the wall outlet you use has an EGC. You know how to test for that.
If it's easier for you can plug an IC into the RCA jack on the RR2160 amp and touch the mm test lead probe to outer shell of it.
Set the mm to V ac .
For the heck of it after measuring from the input signal ground of that jack to EGC ground, repeat the test on the the analog input jack signal ground you oroginally had the phono preamp ICs plugged into. The day of the electrical shock, spark event.
i unplug the preamp from power. [ME (Dead NO power)]
I unplug all interconnects from preamp.
I leave the grounding wire connected, which grounds the preamp to the record player tone arm.
I put one lead of the multimeter in the EGC coming from the outlet where the preamp, amp, and CDP are connected,
and the other lead on the RCA output of the preamp
and I read 121Vac on LoZ.
I now unplug the (grounded) power cord from the turntable
and do the same test (still with the ground cable attached to the preamp and the tone arm) and see 0Vac.
/ / / / / / /
My response:
Sounds to me the difference of potential, voltage, of 121Vac is coming from the TT 120V power section that feeds power for the motor.
121Vac fault circuit path through the mm volt meter.
121Vac Hot conductor from wall outlet to >>> TT motor section to >>> tone arm ground to >>> ground wire to >>> phono preamp ground lug, metal enclosure of preamp, signal ground (outer shell) RCA jack to >>> test probe lead of muli-meter >> through volt meter >> out test lead probe wire to >>> EGC of wall outlet.
The two points for the voltage,
(1) the Hot conductor at the wall outlet that feeds the TT
* (There has to be problem in the 120V section of the TT. Will need to check that out)
(2) The EGC at the wall outlet that feeds the CDP and unplugged phono preamp
Your job now is to verify there is continuity from the 120Vac Hot prong on the TT IEC inlet connector and the tone arm ground. That just don’t seem possible...
You get to try out the continuity setting on the mm.
For this there can’t be any LIVE voltage at the points you will measure for continuity.
Leave TT unplugged.
Test:
Power Switch on TT must be Switched ON...
First set mm to V
Measure for voltage from the tone arm ground lug to one of two line prongs. I don’t know which one is the actual Hot prong so you will measure from both.
You should measure zero volts from each one (on the IEC) to the tone arm ground lug.
No voltage... Correct?
Next move the switch on the mm clockwise one setting. That should be the continuity setting.
Touch both metal probes to one another.The meter should make an audible sound. You probably will see something displayed on screen as well. (It will in the mm instruction manual.)
Next, touch one mm probe to the arm ground lug and the other probe to each of the outer prongs on the IEC inlet connector.
May may not hear the audible sound, look at the mm display. It may show a low resistance measurement.
I forgot to mention in my above post that the EGC for the TT has to be open, broken, somewhere. It could be at the wall outlet the TT is plugged into or it could be open, broken, at the other side of the TT IEC EGC ground prong inside the TT, or the point the ground wire connects to the TT itself...
Because you don’t know where it is open, broken, DON’T plug the TT grounded power cord into any other wall outlet to find out. You could really cause electrical damage to the TT 120V electrical wiring system.
If you haven’t started the continuity test I wrote in my above post there is quicker way test if the Hot conductor is faulted somehow to the tone arm ground.
Disconnect the tone arm ground wire from the phono preanp ground lug.
Plug in the TT power cord into the same wall out you had it plugged into last night.
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Set mm to V (volts).
Measure for voltage from the EGC wall outlet you used yesterday to the tone arm ground. you should measure 121Vac.
This conversation is going a little nuts. Testing with multiple devices for this is nonsense, except maybe as a learning exercise for new techs.
. What a bunch of BS.
But yet the OP has found the problem. It appears to be the TT. We will know for sure when he posts back. For a layman, Imo, @obarrettdid a pretty good job.
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Just curious, what are your hands on electrical troubleshooting qualifications experience?
It’s most likely a major issue with your meter. A good meter should accurately measure a hard voltage in either standard or LoZ modes.
"It’s most likely a major issue with your meter. A good meter should accurately measure a hard voltage in either standard or LoZ modes."
No, it’s not a problem with the brand-new multi-meter.
"isn’t that it? 69Vac on LoZ is a major issue, right?"
First a digital voltmeter with a LoZ circuit meter setting incorporates a load across voltmeter circuitry. That pretty much eliminates phantom, ghost, false, AC voltage measurements. I believe I read in the manual for the Klein multi-meter, (the OP bought), the load resistance is 3K ohms.
There is a great example of how it works. The unloaded voltage reading measured 121Vac (Using the V setting on the multi-meter.)
The LoZ measurement of 68.9Vac reading indicates there in not a Bolted Hot ground fault. Bolted? A solid Hot to ground electrical fault. The LoZ 68.9VAC tell me the is a VD, (Voltage Drop), in the Hot to ground fault. Exactly what is causing VD, series resistance, I have no idea. I just know from @obarrett posted his voltage measurements it is not a Bolted Hot to ground fault.
FWIW, for troubleshooting lose or open electrical wiring circuits in the electrical field a regular multi-meter is worthless, unless it has a LoZ setting.
A regular digital voltmeter internal resistance is in the megohms.
There is continuity from the ground prong of the TT to the tone arm ground lug. No continuity from either of the other two prongs of the TT.
OK
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I attached one three prong power cord to the outlet where the amp/preamp/CDP are connected and then the other to the outlet where the TT is plugged in. I turned mm to V/LoZ, attached one lead to the ground of one, the other to the ground of the other. 120Vac.
IF true that indicates the wall outlet the TT is plugged into has a Hot equipment ground contact at the receptacle. (At this point there is not an internal Hot fault in the TT)
Before I go any farther... Test the receptacle as you have the others for the correct AC hot and neutral connections polarity on the receptacle outlet and from the Hot to the equipment ground contact. EDIT. Use both the V and LoZ mm settings.
Is the Electrical panel for your outlets in your apartment? If not do you have access to where it is located?
I'm not sure preforming the same test for checking the wall outlet the TT plugs into for reversed Hot / neutral wiring connection to the duplex receptacle outlet and to check for the presence of an EGC will work in this situation. Don't see a receptacle Hot equipment very often.
I've looked at different scenarios for how the equipment ground could be Hot to a known EGC ground and the test with the mm would be flawed.
The most common instance is when an equipment ground is not present at the outlet box. Therein a two-wire branch circuit wiring. A homeowner replaces a two-wire duplex receptacle with a three-wire grounding type duplex receptacle. He wants a ground, so he installs a jumper wire from the neutral terminal on the receptacle and connects it to the safety equipment ground terminal. Called a Bootleg ground. Very Dangerous! It doesn't matter if a plug-in circuit tester is used, or a digital multi-meter is used it will show the presence of a ground.
One danger with a Bootleg ground is if the Hot and neutral conductors are reversed on the duplex receptacle. That's not good... The ground contact of the outlet will be HOT!
Is that what you have? Maybe, maybe not. You measured two different voltages in an earlier post. On V 121Vac and 68.9Vac on the LoZ setting. For that to happen with a bootleg ground there would have to be a poor and or corroded connection. The high megohm internal circuit of the mm V setting won't add any load to across the high megohm Voltmeter Like the LoZ setting will. Could that be the case. Maybe. But the only true way would be to pull the outlet out of the box aways for a look.
I cannot advise you to do so.
First, you are not the owner of the building.
Second, the breaker feeding the outlet would have to be turn off. And verified 100% it is dead.
Third, and very important reason you said the building is old. Hard telling what type insulation covering was used on the branch circuit wiring. If really old wiring it could rubber and cloth insulation. That stuff gets old the rubber gets really hard and brittle. It doesn't like to be disturbed.
It's time to call building Maintenace. A hot safety ground is definitely electrically dangerous. A reversed hot and neutral on an outlet is also electrically dangerous.
I believe I have a way to check the duplex receptacle outlet the TT is plugged into.
I'll post it later.
For now, hopefully for the last test, the solution would be to use another EGC grounded outlet. Like the subwoofer receptacle. I don't want you to use the CDP receptacle though, for the test. The CDP, I believe, because it uses the EGC is grounding all the non EGC equipment. It was providing the return path for hot to EGC faulted circuit.
The properly EGC grounded TT, (Which I don't think is right), will do the same.
(FWIW I doubt the CDP signal ground is directly connect to the EGC grounded CDP chassis. Just a guess the signal ground is in series with around a 10ohm resistor. This helps prevent ground loops, hum.
As for the TT EGC connected to the tone arm, I would contact the VPI support on that. That makes no sense to me.
It seems like next I should call a professional electrician.
I should consult with a professional either way though.
I agree.
You should call the building manager or Landlord. They more than likely have their own Electrical Contractor they use for the electrical work in their buildings. You shouldn’t have to pay anything. Some of the electrical is unsafe.
FYI, I would remove the 2 to 6 outlet "converters" for the day Electrician is scheduled to come out.
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As for the measurements in your above post.
Outlet 2 (TT, subwoofer):
RL: 120Vac
LG: 0.36Vac
RG: 120Vac
The Hot / neutral polarity wiring is correct.
Hot (small slot) to ground 120Vac is correct.
Neutral to ground 0.36Vac looks good.
If it were me, I would buy one, or two if needed, descent plug strips and plug all your audio equipment into it/them plugged into this wall outlet. At least until you can get an electrician to troubleshoot and fix the electrical wiring problems.
/ / / /
Outlet 1 (amp, preamp, CDP):
RL: 120Vac
LG: 120Vac
RG: 0.09Vac
This outlet has the Hot and neutral reversed, mis wired.
Therefore LG: 120Vac Is wrong, not safe.
I would not use this outlet to feed your audio system equipment. To be honest, I can’t see how you can...
Imo, outlet 1 ground is screwed up causing the 120Vac between outlet "1" and outlet "2" equipment grounds. The wire feeding the ground contact on the outlet is actually the branch circuit HOT ungrounded conductor. It’s not a ground conductor. Good chance the branch circuit is only a 2-wire circuit for Outlet "1".
If you have a drop cord to plug into another grounded outlet, that tested correctly for Hot / neutral wiring polarity, you could confirm if it is the cause of the 120Vac measurement.
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/ / / / /
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I was about to send this post when I noticed your latest post.
Looking for info on the VPI Classic TT I found this YouTube video.
Note the steel plate. Apparently, the tone arm tower base is bolted to the steel grounded plate. ??? I don’t have any proof it is though. Fact, you measured continuity between the IEC inlet connector EGC and the tone arm ground lug/ ground wire.
Here is another possible example for the ground contact on the wall outlet, the TT has been plugged into,... to be Hot 120V.
Assuming everything was fine with the audio system until you decided you wanted to tweak the speaker placements.
IF by chance you unplugged the TT power cord from the wall outlet. (Or for any other reason the outlet could have been disturbed using it for other things plugged into it.)
Assuming the duplex receptacle was not grounded. (Therein two-wire branch circuit wiring. Old worn out 2 wire outlet was changed out to new 3 wire grounding outlet by a former tenant.
No wire is connected to the EGC ground terminal
Outlet opening is 1 gang flush rough-in steel switch box.
Hot and neutral are revered on the outlet. Therein the Hot conductor is connected to the neutral side terminal on the outlet. Neutral conductor is connected to the hot contact terminal screw side.
On a regular grounding type duplex receptacle, the EGC contact terminal screw is on the same side as the neutral contact terminal screw.
It is possible the duplex receptacle was not tightly fastened to the wall recessed rough-in box. Odds are it is not.
It is possible if the outlet was disturbed by, Unplugging the power cord and or plugging the cord into the outlet, the HOT neutral contact terminal side and the EGC ground terminal is now contacting the side of the steel 1 gang box. The side of the steel box is electrically energizing the ground contacts of the duplex receptacle.
This one you could safely check.
Remove the outlet plastic plate.
Once removed look at the neutral contact side of the outlet. Does it look like it is against the side of the steel box?
If yes, do you a plastic tea or milk container you can cut out a rectangular piece of the plastic? Slide it between the outlet and the steel box. You can cut a rectangular piece for the other as well.
Slightly tighten the two 6/32 screws that fasten the outlet to the box if needed.
Replace wall outlet cover.
Check the ground contact to see if it is still hot.
No need to reply to either post, unless want to..
If you have any further questions, you can always PM me using the Audiogon messaging system.
Hey Jim, the reason why I didn’t have an issue before is that I wasn’t using outlet 2 before.Everything that needed a ground was in outlet 1. Only after I moved things around could I access outlet 2.
FYI, outlet 2 has an earthed ground. Well, the mm measurement says so. A plug in circuit tester would say so. A Bolted Hot to the EGC ground fault might tell a different story.
Using outlet 1 you didn’t/don’t have a ground. The ground contact on the outlet is HOT 120Vac with reference to an earthed ground. All the metal enclosures of the audio equipment were HOT 120Vac referenced to ground. Even audio equipment that didn’t use an earthed EGC.
The TT power cord is a 3 wire cord. When plugged into outlet 1 it fed the branch circuit HOT 120Vac to the TT IEC inlet connector EGC prong. That in turn fed HOT 120Vac to metal parts of the TT and to the tone arm ground, *(by the way the tone arm was HOT with reference to an earthed ground), to >> the phono preamp enclosure, which made all the RCA jacks outer ground shells HOT 120Vac that contaminated all the other metal enclosures through the interconnect cables signal ground conductor.
Why you never got an electrical shock or had problems with your audio system equipment? There was not an earthed ground introduced into the equation.
So, for the same reason a bird perched on a high voltage power Line doesn’t get shocked.
Now the Squirrel is a different story. He will jump onto High voltage power Line and run down the Line without a care in the world. It’s his dismount from the high voltage power Line to the top of the metal earth grounded pole transformer is his fatal problem. If only he had jumped instead of stepped.
FYI, I am pretty sure the heat radiator shown in the video is earthed grounded. Had you been able to touch it with one hand, (in the summer months), and touched any of the HOT 120Vac metal enclosures of the audio equipment with the other hand there is a chance you would have been electrocuted. Therein dead.
DO NOT use outlet 1, until it is wired correctly by an electrician.
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I suggest you try another test. Plug an OEM power cord into outlet 1. Insert one of the test lead probes into the IEC female ground contact.
Turn mm to V and touch the other test lead probe to a bared (unpainted) metal place on the heat radiator. You can also use the LoZ setting on the mm as well.
Here is a photo of a two wire old rubber cloth covered conductors Bootleg grounded outlet . The wiring is really old. pre-Thermoplastic, PVC, insulated wire. PVC Thermoplastic insulation is really old too. THHN/THWN replaced it, going from memory, in the early 1970s.
Here is good video on Bootleg ground wired outlets. (FYI, a bootleg ground is a NEC code violation. Alwas has been)
How many wall outlets are there in the old part of the house?
The only 100% sure way to check the outlet is look for the jumper wire. Remove the wall outlet cover plate. Good chance using a high power LED small diameter flashlight with the lighting in the room subdued you should be able to see the jumper on ground terminal side of the duplex receptacle outlet without pulling the outlet out of the wall box. (Turn off the circuit breaker at the panel if you are going to do any poking around.
Another sure way is plug in a high current load into the outlet like a hair dryer or portable vacuum cleaner. Anything that draws enough current on the branch circuit wiring to cause a voltage drop on the wiring.
First measure for AC voltage from neutral contact, (longer straight slot of the two.) Notate the small voltage reading.
Next plug in and switch on the load. Check the voltage again from the neutral contact to the ground contact on the outlet. If the outlet is bootleg ground wired the reading will be the as the first measurement. If the measured voltage is a few to several volts lower, it is not a bootleg ground.
But the cheap EZ check tool says that they are correct??? With the breaker tripped and the outlet connected to both wires, I tested for continuity between the white screw with white wire and the green ground screw with NO wire and I have continuity???? Are they somehow bootlegged from inside the outlet?
I assume the 3 wire duplex receptacle was fastened to a steel rough-in box when you used the "EZ check tool", (and with the circuit dead), you checked for continuity from the neutral contact to the green ground screw.
That indicates the steel box is grounded. If the branch circuit wiring that was installed many years ago is only 2 wire that means a ground wire was installed at a later date. I would say, to replace a two wire outlet with a 3 wire grounding type outlet.
Many many, many NEC code edition cycles ago NEC allowed a ground wire could be installed from a steel outlet box to a metallic cold water pipe using an approved pipe clamp. For years a duplex receptacle was considered grounded when fastened to a steel grounded box. My guess that is what you have.
The duplex receptacle that is installed on the grounded steel rough-in box may now be an auto ground type receptacle. (One end of the Yoke of the outlet has a stainless steel clip that puts pressure on the 6/32 machine that bonds the supporting back strap to the grounded steel box.
Years ago before the auto ground clip NEC considered the outlet was effectively grounded to the box with just the two 6/32 screws.
I put in were wired correctly (from duplex back to the panel, black/white/ground) doesn’t this mean that ground for the steel box of the duplex in question must end up back at neutral/ground bar at the main panel?
Several NEC code cycles ago NEC was changed stating branch circuit conductors shall be installed in the same raceway or cable assembly. That includes the EGC. (Equipment Grounding Conductor).
When a steel box is used the EGC shall be bonded to the box. Per NEC if the duplex receptacle is an auto grounding type a ground pigtail is not required from the EGC to the duplex receptacle. The duplex is grounded by the auto ground.
I personally still install a ground pigtail to the ground terminal screw on the duplex recept.
Here is a photo of a two wire old rubber cloth covered conductors Bootleg grounded outlet . The wiring is really old. pre-Thermoplastic, PVC, insulated wire. PVC Thermoplastic insulation is really old too. THHN/THWN replaced it, going from memory, in the early 1970s.
Here is good video on Bootleg ground wired outlets. (FYI, a bootleg ground is a NEC code violation. Always has been)
I spoke to the landlord/my point of contact for the management company yesterday. He repeatedly told me he ‘never had any trouble with the electricity’ in my apartment until now. I don’t think I can make him understand just how serious this is.
Sure you can. You can easily show him, with your multi-meter.
The ground contact is Hot 120Vac to the heat radiator.
My goodness it’s 120Vac on both settings. It is a hot ground. That’s so disturbing. Someone could easily have died and I’m surprised someone hasn’t yet.
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If you have any problem with him just mention you could have been electrocuted if you had touched the radiator with one hand and the HOT 120Vac Amplifier metal case with the other hand. electrocuted, dead.
Don’t forget to remove all of those 2 to 6 power receptacle extenders.
In your video, when you measured for voltage from the receptacle ground contact to the heat radiator the test probe connection to the receptacle ground contact was poor. The 120Vac reading was not a solid contact connection.
You should have used the OEM power cord ground. Insert the mm probe into the center ground contact. That also frees up your hand and you can focus your eyes on the probe connection to the radiator valve and the meter.
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WARNING: I hope you saved the plastic outlet cover plate you removed from the receptacle. When you remove the 2 to 6 outlet extender everything metal you see is HOT 120Vac to anything grounded. Don’t put your body between them.
** EDIT: On second thought. Don’t remove this one. Just leave it be.
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Also in case you haven’t thought of it. You are going to have to move the speakers and audio equipment out of area the electrician will be working. Take some pictures first of the equipment where it normally is sitting. Just in case he asks.
The Electrician needs a minimum of 3ft working space in front of the wall outlets. The more the better. A happy Electrician is a productive Electrician.
Old rubber cloth covered insulated copper wire. This is why I advise a non electrician do not pull an outlet out of a wall or ceiling box in a really old apartment building, or an old house.
The building Landlord has mess. An expensive mess. And more than likely the whole building’s wiring is in the same shape.
Just a guess the electrician didn’t find a bootleg ground jumper wire on the neutral contact side terminal screw to equipment ground terminal screw on the Hot / neutral reversed polarity outlet. (outlet 1.)
I doubt he found a jumper on any of the outlets. The rubber/cloth insulation deteriorated over the years causing the bared copper wire to contact the wire support bracket. There was a 50/50 chance whether the Hot wire or the neutral wire faulted to the steel bracket / box. It’s kind of amazing that both didn’t fault to the box. Dead short.
Neutral fault to the box it’s an earth grounded box. Hot fault to box, a HOT 120Vac to ground box.
The odds are good that there are other outlets in the apartment the electrical wiring is in the same condition
Did the electrician say what type of branch circuit wiring it is? It could be BX steel armored cable. It probably comes through a hole in the back of the box and the clamp holds it in place. In the third picture I thing I can see the cut end of the armor.
I see brick on walls in your photos. Just a guess the building is constructed of brick. ???
Did the electrician say what wiring method he will use to rewire the apartment? The only thing I can see is install surface mount Wiremold.
Did the electrician say what type of branch circuit wiring it is? It could be BX steel armored cable. It probably comes through a hole in the back of the box and the clamp holds it in place. In the third photo I think I can see the cut end of the armor.
I looked again at the photos this morning. I am not sure that is the end of a steel armored BX cable. The empty hole in the clamp beside the one with the wires appears to have a raised ring as well.
Also I do not think the conductors enter from the back of the box. The empty hole in the clamp shows the back of the box solid, no hole, or knock out.
I think the wiring could be old, really old, cloth covered NM cable with rubber/cloth insulation. The cable enters the box from the bottom.
What type of old wiring did the electrician say it is?
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