Did I just cook my preamp?

@jea48 , when my old Radio Shack meter failed the drop test and I needed a new one (like immediately to bias my amp) I went to Lowes (because they are super close) and I bought a South Wire.  How do those stack up?  I saw that they had Fluke meters, but for what I thought at the time was an ungodly amount of money.  I could always upgrade to a Klein; I am pretty sure that now Lowes sells them as well.

No, @jea48 , 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 is not like I am a tech person, but I would like to think that the readings I am taking are close to being accurate.

As far as the bias on my amp, it is currently set at a few hairs (on both sides) under 260 mA.  Without going back and checking, I am about sure the manual says 270 to 300; back at the end of '17 when Cary tech support would still take telephone calls, in some context the subject came up and the tech guy said to shoot for 40 to 50 mA a tube.  (I think the context of that conversation was how to bias it if running less than six tubes per side.)  @decooney told me that when he had his V-12 he liked it set way lower, but when I tried that I didn't think I liked it as well.  Who knows, maybe it was psychological.  on my end.

Just curious what are you setting the DC ma bias at?

@jea48 , I tried to follow this thread but it became too complex for me to understand what was happening, so I apologize if this question was asked and answered and I missed it.  

Bootleg grounds:  now I understand what they are and the reason someone might wire an outlet with a jumper from neutral to ground in order to put a (3 hole) grounding receptacle  on a (2 hole) ungrounded circuit to make it pass the test with a real basic EZ CHECK circuit tester.  Since my house was built in early 1960s  and has (2 hole) ungrounded outlets in the back of the house and (3 hole) grounding outlets in the front, although the grounding outlets all pass the EZ CHECK circuit tester, it still seems like my house might be a candidate for those grounding outlets to be bootlegs. 

I went to google to look for a simple answer of what to look for with an AC VM to identify bootlegged and normal outlets and got drastically conflicting results from AI.

Again, I apologize if you previously covered this, but is there a way to verify with an AC VM whether a 3 hole outlet has been bootlegged or not?  I compared an outlet on a circuit that I installed myself that I KNOW is NOT bootlegged, and ground to neutral reads 0.105; then on a 3 hole outlet that was there when I bought the house and it reads 0.25.  (My meter does not have an LoZ setting.)  

Do those readings mean anything, or is the only way to know for sure to remove the older grounding outlets and visually inspect them for jumpers from neutral to ground?  I am getting the impression that there are more expensive meters that will verify whether or not a bootleg ground was used?

Thank you, and again, my apologies if I am asking a redundant question on this thread.

@obarrett   I appreciate this educational thread and hopefully it's okay with you if I piggyback on it just a bit more.

@jea48 , you asked how many 2 hole outlets I had in the back of the house, and there are 3 per bedroom making a total of 9.

BUT:  I removed two of my "grounded" 3 hole outlets to inspect them for a bootleg ground.  The two I removed do NOT have a jumper from a neutral (white) screw to the green ground screw, but they also do not have any ground wire connected to the green ground screw. In other words, the only wires connected to those two outlets are the black wire and the white wire.  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?

Thank you for taking all of the time that you do to provide education and assistance to those of us who have a rudimentary grasp, or probably even less in my case, and struggle with the subject.  I certainly appreciate all your help over the few years I have been on A'gon.

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.

You are a genius, @jea48 !  Thank you much for getting back to me on this!!  To check for continuity from the white screw/white wire to the ground screw I remembered I had the outlet pulled out a bit from the steel box, so I just now did the same thing, and I must have had the screw lightly touching the box the first time.  This time, with the breaker tripped,  I made sure the outlet and hardware was completely clear of the box and, voila, NO continuity.  Then I let the screw touch lightly, and presto--continuity.  So I set it up so I had no continuity, put the EZ Check back in, flipped the breaker back to ’ON’, and the EZ check read as it should--"open ground."

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.

How kosher is this set up that I have?

Oh, and on edit:  I have  three duplex outlets for circuits I put in myself right next to the duplex that I just checked.  With all the outlets installed and breakers tripped, I do measure continuity from an equipment ground hole of the duplex in question to an equipment ground hole of the duplex outlets I put in myself.  Since I know for a fact that the duplexes 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?

Thanks again for getting back to me!

It’s fine. It’s Grandfathered in.

That’s a relief, @jea48 .  As long as I am not living in a potential electric chair or an incinerator  I can live with it.  I was going through in my mind what I was thinking I was going to have to do to run replacement circuits for replacement duplexes, and I wasn’t liking it, but time is one thing that I have enough of, so if I had some kind of bootleg set up I wasn’t understanding, I was going to get started on it.

Once again and as always, I thank you for the education.

@obarrett , I don't suppose you have renter's insurance?