testing a crossover

You can find all the photos here

https://systems.audiogon.com/

Without drivers connected,
The HF measurement should equal to the DC resistance of the 0.22mH inductor.
The MF measurement should equal to the DC resistance of the 2.5mH inductor + 2.2Ω.

Hi guys, sorry for the very late reply in my/your quest to sort this out,ive done a couple of thing since, taken advice on multi meter/s, fitting fully charged battery's in the digital and analogue multi meters,both tested by using an 8ohm resistor, I use for running in component/gear, just incase, removed all wire to and from the x over and cleaned the board,and flowed every joint,so there no chance of dry joints and shorts,also i have done a continuity test from every component lead to pcb tracks,all joint good, please find results of questions asked.
multi meter set to ohms-
between mid pos and neg  2.7 ohms
between tw   pos and neg  0.002 ohms
mid/high inputs  OL {held on for 5 secs}nothing changes
mid/high inputs {reversed} OL{held on for 5 secs}nothing changes
when run with one amp,in bi-wire mode both pos are NOT connected the same goes for the neg wires,the amp has 2 sets of switched speakers terminals,i use one set for the bass and the other set for the mid/high,so the two speaker cables do not touch each other 
resistor showing short{5w2R2J},which i measured using continuity mode,just above IP neg,when doing an ohms test is reads 2.3ohms

Diode test on mid/high -OL
when reversed is flashes 2.2xx,then goes to OL
every time i reverse leads it flashes something {2.2xx}not sure its voltage,it doesnt tell me that

further to reply to imhififan1 im not sure how to test for what your asking 
" Without drivers connected,
The HF measurement should equal to the DC resistance of the 0.22mH inductor.
The MF measurement should equal to the DC resistance of the 2.5mH inductor + 2.2Ω.".
Not sure what 0.22mH is and also 2.5mH inductor +2.2 ohms,i know what the inductors are but not sure on mH.
Also i have found that one of the capacitors has a dead short short when tested in dioode mode,{still soldered into pcb},on both x-overs, when the rest show OL,not sure if that has a bearing on anything, just throwing it out there.
Any guys sorry again for the late reply,i hope your all still speaking to me, thankyou again for all your help.
Kind regards
Mk
ps i have posted some more pic of cap showing short and the resistor ive tested
thx again MK

between mid pos and neg 2.7 ohms

Okay... before you said that you were getting 0Ω across the MF +/- outputs with the driver disconnected. Is this the same measurement? If it is then it's close enough not to worry about for this exercise. As imhififan said:

The MF measurement should equal to the DC resistance of the 2.5mH inductor + 2.2Ω.".

Take into account there's a bit of tolerance on those resistors as well as the accuracy of your meter.

Not sure what 0.22mH is and also 2.5mH inductor +2.2 ohms,i know what the inductors are but not sure on mH.

Although the inductors will have some DC resistance you can pretty much ignore it for the purposes of this excercise as long as you're in the ball park of the resistor values.

Also i have found that one of the capacitors has a dead short short when tested in dioode mode,{still soldered into pcb},on both x-overs, when the rest show OL,not sure if that has a bearing on anything, just throwing it out there.

If that's the 6µF cap then the reading is correct as it's in parallel with the 2.5µH inductor which will have very low resistance at DC.

If I've understood you correctly then the tests don't seem to have turned up any results that would cause the amplifier to fail.
Maybe someone else will spot something I've missed... or maybe the tech didn't find the real fault in the amp when it was sent in the first time.

i think we may have a misunderstanding some times about ,when i use a diode test and ohms test,i think i haven't explained it well enough,or used the wrong test for finding this fault
originally when i tested the speakers{in the beginning}there was NO reading on ohms for the test when testing the mid/hi speakers on the terminal speaker posts on the back of the speakers,
please see first tests
"          LEFT SPEAKER                                  /
 RIGHT SPEAKER
                speaker terminals with everything connected on both speakers

     MID/HIGH        0.0 ohms                             /
    MID/HIGH    0.0 ohms
       BASS           7.9 Ohms                             /
       bass          6.8Ohms

                                      DRIVER TEST DISCONNECTED FROM X OVER
          TWEETER 8 OHMS                                 /
    7.9 OHMS
              MID 6.3 OHMS                                   /
         6.2 OHMS
             BASS  6.1 OHMS                                /
       6.0 OHMS

     CONTINUITY TEST ON X-OVER WITH DRIVERS REMOVED USING DIODE FUNCTION
                                             between positive and
negative on x over
         HF                  000.2 {dead short}
         /       000.2 {dead short}
         MF                  000.5
              /       000.5
         LF                     OL.
                /        OL.
MID HIGH INPUT IP     OL.                                 /
                OL.
   BASS INPUT            OL.                                 /
                   OL.
                                                  OL. BEING NO CONTINUITY

                               TEST TESTED AT/ON X-OVER SPEAKERS CONNECTED OHMS

         HF 0.0002 OHMS                                      /
              0.002 OHMS
         MF 0.0001 OHMS                                      /
               2.0 OHMS
         LF   6.4 OHMS                                          /
                   6.3 OHMS
what i see,is that when testing a speaker from the speaker cable posts,disconnecting from the amp,i should see how many ohms the speakers are,in this case they are 8 ohms speakers,and i have tested them on other ocassions,after re-wiring them once another time when i re-capped them,just as a check for shorts or problems and they have always read in the ball park of between 7.8ohms and 8ohms,for both bass and mid/hi ,now it doesnt read that,the bass is ok but the mid/high reads 0.0ohms,i only checked them,when my technican asked me to after the first time he repaired the ampand it blew,and sure enough there was a problem,does this throw any light on what your thinking,or have i really badly explained the problem,really sorry if i have.
regards
MK

Okay... I think I am having trouble following. Also there might be a bit of confusion around resistance (DC) and impedance (AC). When you read the resistance across the loudspeaker terminals it has very little to do with the nominal impedance of the speakers (this is even true if you measure across the driver itself). You have a high pass filter on both the mid (12µF) and the tweeter (4.2µF) so if everything is working correctly you should get an open circuit when you attempt to measure resistance across the loudspeaker posts with everything connected.

I’ll tell you what I think I’ve understood and you put me right if I’ve misunderstood:

1) Original test with everything assembled showed 0Ω resistance across the MF/HF +/- terminals on the back of the speaker.
2) Those terminals connect directly to IP+ and IP- on the crossover PCB.
3) With the crossover disconnected the DC resistance between IP+ and IP- was open circuit.
If points 1-3 are correct and you’ve put it back together and measured 0Ω across the loudspeaker terminals then there’s a short somewhere between the terminals and where the wires connect to IP+ and IP-.

4) With everything disconnected from the crossover you measured the resistance across the copper you have marked M+ and M- and got 0Ω.
5) According to the schematic M+ and M- should be connected (at DC) via 2.5µH inductor (of negligible DC resistance) and a 2.2Ω resistor.
6) On your most recent test you measured 2.7Ω.
If point 4 was true then you’d most certainly have overloaded your amp and would have got no sound from the driver... however the most recent measurement shows no such problem.

likklegerry - Thanks for your test data, looks like everything except the Lo and Hi bi-wire connections are in line with what I expected. Just to be clear, with the amplifier and other electronics off, an ohm meter test between the HF+ and LF+ terminals should be 0.0 ohms. Same should be true of the HF- and LF- terminals. This can be measure at the speaker or amplifier terminals.
The diode mode tests at the HF and LF connectors also show what I was expecting.
The dc resistance measurements with the drivers disconnected are in line of what is expected too. Don't worry if it's mH or not, trust us, it is mH.
Which capacitors (value) is showing shorted in the diode mode? The caps themselves should be tested in the ohm mode. I will continue reading an ask questions or make comments as needed.
Please do the resistance test between the HF and LF terminals as described above. This is in the bi-wire configuration with all wires connected to one amplifier.

between the HF+ and LF+ terminals should be 0.0 ohms

do you mean open circuit?.. Not being snarky, just checking :-).

You have made me think of something though... if you forgot to take the shorting plate/wires off the loudspeaker posts when switching to a bi-amp config you could get enough current flowing between the two amplifiers to blow one of them.

pragmasi - I assume your post above was meant for me? I guess I really didn't need an answer to the last 2 sentences of my above post because I'm sure the answer is really yes, and maybe confusing to some.
You are absolutely correct about forgetting the jumpers when switching from bi-wiring to bi-amping. That could easily blow one or both amps used in a bi-amp configuration.

Dude, you should have followed my advice and you'd be done by now. :)

@erik_squires 

Dude, you should have followed my advice and you'd be done by now. :)

The best way I know of to test a crossover is to generate an impedance graph. You can use DATS V2 (or is it now up to V3) or you can build a jig and use Room EQ Wizard’s app for this.

How is that advice?.. it's not going to help anyone who doesn't already know what they're doing.

erik - If you are not really going to try and help, stay out of it! Dude...

Pragmasi-im really sorry,but there are no open circuits, i have closed circuits{shorts},which are the problem,surely if i have a short internal of the x-over ,before it reaches the mid and high drivers this will draw current.to be honest,i thought i knew how to test a speaker box,it seems im totally out of my depth here,which i knew,but was just asking for basic help,101 style,im no way an electronics engineer ,hobbist at most,not even that,so giving me eqations to do ,when i dont even know what the sybol mean ,is a strtch too far,its like me asking to to calculate the dwell angle and timing on a camshaft for a super charged car,if you dont know,it will take a long time to learn,i have one simple question why does the mid/high on the crossover have a short within the x-over,when the bass driver does not,im just not grasping even that,and how come there is not an ohms reading for the mid/high at the binding posts,please please excuse my ignorants,
mk

ps was that pragmasi or eric which posted the equation post ? 

shorting links on speaker binding post havent ever been used,to go from bi-wire to normal two wire ,or bi-amp to normal two wire config

fiesta-"  an ohm meter test between the HF+ and LF+ terminals should be 0.0 ohms. Same should be true of the HF- and LF- terminals. This can be measure at the speaker or amplifier terminals."
measurements for above,taken on the x-over 
both OL ,ohms

Pragmasi-im really sorry,but there are no open circuits

Absolutely nothing to be sorry about at all... would just be good if we could help you fix this.

shorting links on speaker binding post havent ever been used,to go from bi-wire to normal two wire

Shame... thought I was onto something there... how do you connect the terminals when running from one amplifier?

It'd be useful if you could describe where you're measuring the short circuits using the references you've added to the PCB with a sharpie.

Would be great if we could all help you get to the bottom of this.

pragmasi- 1) Original test with everything assembled showed 0Ω resistance across the MF/HF +/- terminals on the back of the speaker.
2) Those terminals connect directly to IP+ and IP- on the crossover PCB.
3) With the crossover disconnected the DC resistance between IP+ and IP- was open circuit.
If points 1-3 are correct and you’ve put it back together and measured 0Ω across the loudspeaker terminals then there’s a short somewhere between the terminals and where the wires connect to IP+ and IP-.

totally correct

4) With everything disconnected from the crossover you measured the resistance across the copper you have marked M+ and M- and got 0Ω.
                                   -not sure where i said that-
                                       No it reads 2.7ohms
hope that helps.
Mk

likklegerry - Just forget that question, I already understand. Providing your crossover passed the test using the diode mode at the mid/high bi-amp inputs, which it appears to have. I think you are good to go. Just perform that same test with the drivers connected. I'll get back in touch later today.

i had a good play about with them both today,x-overs,couldnt find a problem ,maybe i should just strip them down,or one,check all parts then reasemble,not sure how to test the inductors though,as i can see i dont know enough, I can test parts but all this equations for test with a multi meter only,idont evem know what mH is !!??.Didnt think this would be that hard, obviously im wrong again.
cheers guys for all your help

1) Original test with everything assembled showed 0Ω resistance across the MF/HF +/- terminals on the back of the speaker.
2) Those terminals connect directly to IP+ and IP- on the crossover PCB.
3) With the crossover disconnected the DC resistance between IP+ and IP- was open circuit.
If points 1-3 are correct and you’ve put it back together and measured 0Ω across the loudspeaker terminals then there’s a short somewhere between the terminals and where the wires connect to IP+ and IP-.

totally correct

Okay, that should narrow it down a bit and you can stop worrying about the crossover. If you only get the short when the loudspeaker is reassembled then you're looking for something between the crossover PCB and the loudspeaker inputs. If you disconnect the crossover you should be able to track it down... what are the binding posts on the loudspeaker mounted to, plastic or could it be anodized aluminium?

ps was that pragmasi or eric which posted the equation post ?

That was me re-posting Eric's advice to point out how it wasn't very helpful.

Stop, I would not strip any parts off either board. The data, answers to my questions, looked promising. You’ve already done a lot of visual inspection and testing. The most recent pictures, the cap with the blue circle around it, what is that? Suspect bad part? What is the printed value of the cap including the voltage rating?

In one photo I can read 3.9uf/250V. When you drew and label the components on the circuit board the 4.2uf should have been 3.9?

I don’t know it’s can be of any help, you can find the xover schematic here:

https://ucarecdn.audiogon.com/a89e98dd-d4a0-4acf-9f74-934683ea9b70/-/autorotate/yes/

@likklegerry-    re: Your first post on this page:

 "Diode test on mid/high -OL
when reversed is flashes 2.2xx,then goes to OL
every time i reverse leads it flashes something {2.2xx}not sure its voltage,it doesnt tell me that"

      Only here to address that question, as I didn't notice any other answer (just FYI/fun facts).

       A non/bipolar cap, when presented with DC, will charge in one direction.  Reverse the polarity and it will discharge and charge in the opposite direction.

            That's what your DMM is reading, for that brief instant.

       As an experiment: Connect a non/bipolar cap in series with a speaker.    Don't use a tweeter, unless it's expendable.

        Touch a 9V battery's + post to the open lead of the cap and -, to the open speaker terminal.    Hold it there, for a few seconds.     Longer: the greater the cap's values

         Reverse those connections and you'll hear a *POP, every time.

                                        *The cap, discharging

thank you all guys i am so honoured for all your help,but i think i am going to go for the simple fact,that,i think all these problems may have started when i changed out all the caps,on the cross over,im going to find the old ones which i removed,check there values again ,against the schematic i have uploaded ,and maybe ask you guys if they are compatible/same,like for like to do the job,i received a private email,that explained that they maybe different,although i did get them from Wilmslow audio and stated they where for an upgrade for my speakers,but it just might be worth trying the obvious stuff first,as soon after the change out,is when this problem started,2 years ago.still dont understand why it works with only one power only though,and not two.weird.
Just to answer your last question though.

pragmasi,the the binding posts holder is plastic,no short there.
i connect the speakers via two cables{pairs]to a four post bi-wire termial posts,in one amp mode,i use the same cables and posts ,but use the two sets of speaker post on the back of the amp.

Hi fiesta the blue circled cap is 6.8uf 250v cap,which is the one that looked like it had a short,but after desoldering it from the board ,it tested on,no continuity and good cap testing values,so was red herring,someone said it was because it was in parallel with other parts reason for show a short
fiesta-
" In one photo I can read 3.9uf/250V. When you drew and label the components on the circuit board the 4.2uf should have been 3.9?"
I didnt draw the x-over i received it from wilmslow audio and posted it here,

maybe i have the wrong caps,i will dig out the old ones and check/compare.

hififan,i checked out the link,had a look at the schem,that one is similar,but are they not all individual to every speaker?,im not sure.

rodman,i dont really want to go down that route of testing with expendable drivers and amps,its exspensive, when things go pop,but thanks,plus the speakers work,but after a few hours the amps goes pop,so i dont think its an obvious fault,but possibly a high draw problem,putting strain on the amp driving the mid/high drivers,but thanks for the input.infact thank you all for your imput.
im going to check out the cap values and tyes again ,against that schematic.

ps,thankyou thomas for the explanation and time,you know who you are.

pps,does any know how to remove hot glue ??,the easy way

pps,just to add to my explanation ,i feel that there might be a value issue here,what do you guys think,ive possibly fitted the wrong value caps{i dont think i have,as i would have compared them before fitting}but they are definitely different type of caps,ill dig the old ones out and put the old type and what i replaced then with on here later,but today i have to do some concreting, my wife is going crazy.
thanks again guys
M

Sorry to state the obvious but, why not just take the xovers along with the schematic to your local eletrician who will solve the issue in a jiffy for a few quid -- if that:)
There's a short somewhere in the tweet xover and that's tricky to identify from afar It could be a component failure, a wrong connection, etc)!Good luck

@likkelgerry-  Apparently: I wasn’t clear enough, when answering the question you posted (on 6/22).

     NOTHING in my answer has ANYTHING TO DO, with the problem you’ve experienced. (specifically why I stated, "just FYI/fun facts")

     Any PROPERLY FUNCTIONING nonpolar/bipolar capacitor, will act the same way, when presented with DC.

     Once they charge in the direction of the DC current’s flow, they BLOCK any further DC, which (when used as coupling caps) is their intended purpose.

     What I suggested would not damage ANYTHING bigger than the typical tweeter, OR: I wouldn’t have suggested such.

                          Obviously: my use of the word, "POP" triggered something.

                             btw: I still stand by my first post to this thread (on 6/10).

     IF your crossovers were truly functioning properly (everything sounded as it should), when correctly connected to ONE amp, all of those crossovers’ internal components were fine, to start with.

                                              "...my wife is going crazy."

                                                             I’ll bet!

Hi rodman,whn everything is connected in a  one or two amp system is in use ,everything sounds great,the sound is amazing, slightly better with two power amps {obviously},but nothing is a miss,its just that it keeps blowing one amp,the one driving the mid/highs,and that is the only problem,i just cannot find out why,but every time it blows an amp,it cost me a fortune to send to Sofia about 200 miles from where i live in Bulgaria,as its the only tech i can find in the country,postage alone is £50plus the repair another £100 plus.


gregm3,iits not esay in bulgaria to find a electronic HIFI tech,,to find any tech is a job in its self,a good one is like rocking horse ..

Cheers guys Mk

The testing of the mid/hi input terminals showed the caps at that end of the circuit were charging and discharging. No shorts or problems were noted in that particular test.

I didn't know you were in Bulgaria, that explains the delays in communication. I think a few more tests are the only thing that is required to conclude that the issue is solved. I'm still willing to try.

The fact that the speakers and amps worked of a couple or more hours is a hint that the problem may not be in the crossover. Are you SURE that when you bi-amped the speakers after getting the amp back from servicing that you didn't forget to remove the second set of cables to the low and mid/hi inputs? If the amps were connected in the outputs, even just one wire like the negative or positive between amps, that could have caused the amplifier failure.

I don't believe there is a problem that exists on the crossover any longer. Let's just do a few more tests. 

I'm curious, do you have a list of parts that were replaced when the amp was serviced? A list from the first repair and one from the second repair might shed some light on a potential cause for the failures.

rodman - Just FYI, I did explain that the diode function test was to verify the charging and discharging of the capacitors. This was in my post of 6-16 @ 7:06pm. His answer showed there was no longer a short at the inputs of the mid/hi amp connections.

@fiesta75-   I don't see a post, from you, dated 6-16 @ 7:06pm, at all.

     Nor anything vaguely explaining why nonpolarized caps behave like they do and are supposed to, when presented with DC, which was my ONLY intent and, as I've mentioned twice now, "just FYI/fun facts"..

      I did see something about connecting DC, and what readings may occur, at the terminals, from you.

      Given his question, regarding his DMM readings, when changing the polarity:   "Diode test on mid/high -OL
when reversed is flashes 2.2xx,then goes to OL
every time i reverse leads it flashes something {2.2xx}not sure its voltage,it doesnt tell me that"      to which I replied,  wasn't even posted until 6-22 @5:10am, I have to ask:

                                                     Are you a prophet?

Here are my posts from that day:
06-16-2021 5:40pmOkay, its been a rough couple days. I just got done drawing the schematic and looking at the words and measurements again. Just one note, do all measurement in the resistance mode, not in the diode mode as the diode mode really doesn't tell us anything. You don't need to disconnect one end of the resistors to check each resistor. So with no drivers attached, between the midrange terminals on the crossover board, you get close to 2.2 ohms, but it's not a dead short correct? For the tweeter terminals, you get close to 0 ohms, but not a dead short correct? At the mid/hi amp inputs, you get essentially OL after holding the probes on the terminals for few seconds, correct? What happens when you reverse the leads on the mid/hi amp terminals? Does the meter go to (-) xxx.x ohms then to (+) xxx.x ohms before going to OL? This is a dumb question, but just so I understand everything. When you use only one amplifier to power the speaker in the full range (bi-WIRE) mode, the (+) terminals of the inputs are connected together. And separately, the (-) terminals of the inputs are connected together, correct? The photos are gone, but don't think we need it again. From your DC voltage measurements at the amps, they look healthy. Please answer all of my questions in order, so we don't get confused, thanks.fiesta75404 posts06-16-2021 5:48pmWhich resistor, if it's STILL showing a dead short or 0.00 ohms? This is the one mentioned in post 6-16 @ 12:59amfiesta75404 posts06-16-2021 7:06pmCORRECTION, sorry. The last test on the mid/hi amp terminals on the crossover board; when I asked to to test and then reverse the meter leads and test again. The multimeter should be set on the "diode" test mode, not ohms. The readout should display some voltage then go to OL. When you immediately reverse the leads, the display should read -x.xxx volts, then change to +x.xxx volts before going to OL. Hope your meter has a diode test function, but it's not absolutely necessary. This test just shows that the caps are charging in both directions.
I still can't explain why the system worked with one amp when the mid/high amp was in repair... This is troubling.

rodman - I appreciate your comments. I just don't want the OP to do anymore work on the boards before doing tests. It seems like he is doing rework in the middle of the tests and that could make some tests invalid. This could create more problems as I'm sure you know. The only test I want from him before finalizing everything is the dc resistance across the tweeter terminals of the board, because his last info on that makes me think the resistance he measured was below what I expected from a 0.22 mH inductor. All help is welcome.

**likklegerry - Small difference between the original capacitor values and the ones you installed will not cause failures of the amplifiers. If anything, it would have a SLIGHT chance to damage the tweeter or midrange driver. Since it appears that the value of the original capacitor for the tweeter was 4.2uf and the one you installed is 3.9uf, that would very slightly raise the crossover frequency and absolutely NOT cause damage to the tweeters or amplifier. The caps you installed will definitely improve the sound, so please just leave them in.

imhififan - That was very helpful, thank you!

@fiesta75-     " I just don't want the OP to do anymore work on the boards before doing tests. It seems like he is doing rework in the middle of the tests and that could make some tests invalid. This could create more problems as I'm sure you know."

                              I get that and agree, fully!

       Still believing the problem to exist outside of the crossover components themselves: I'll stop flapping my fingertips!

     

@likkelgerry-    I do not envy you being so far from someone versed in electronic repair.

       Here's hoping you are able to locate the issue and get it resolved, without having anything further go awry with your amp.

        Unless the bi-amp configuration made a MAJOR leap upward, regarding sound quality, to your ears; I'd button things back up and run with one!

         Meanwhile: take the Wife OUT for some Meshana Skara or Mousaka and help her relax!     Top it off with some Marudnik (are wild berries in season over there?) and make her love you, again!

                                


       

Please look at this photo:

https://ucarecdn.audiogon.com/32d4343f-f8e2-4de2-95f7-2e0766972c94/-/autorotate/yes/

If that is a short, for bi-amping, it will connect two amplifier output together through the 3.5mH inductor and the 3.3Ω resistor. There could be more similar problem spots on the PCB that we can’t see from those photos, that was the reason I suggest OP to clean up the PCB and reinstall components.

imhififan - That is an excellent catch. I was beginning to think along with rodman, that maybe the problem was outside of the speaker crossovers. I think you may have nailed it. I suppose the single short could have caused both channels of the amp to have failed, or maybe the other board has similar issues? I have asked OP about a list of parts that were replaced when the amp was serviced, wonder if he has that info. What do you think about the lower than anticipated resistance measured across the 0.22mH inductor?

wow,such a lot of input,thx guys.ok
Fiesta 1st," Are you SURE that when you bi-amped the speakers after getting the amp back from servicing that you didn't forget to remove the second set of cables to the low and mid/hi inputs? "
the two amp to speakers where wired correctly,the cables are all marked up correctly left/right,plus minus, and they have different plug,banna and another type,so it impossible to mix them up,plus i dont ever use jumpers on the back of the speakers.
Sorry,not parts list available, he wouldn't give me one,i asked but got no reply on that score.he said it was getting too hot and fitted a fan after repair,which i wasnt keen on ,as i see that as covered up WHY it is getting too hot.
On doing re-work,all i have done is,removed the cables from the x-over and tested continuity from every component to the track on the PCB,every thing checked out,also i clean up the board with pcb cleaner,to remove flux stains.
change out from ,  4.2uf and the one you installed is 3.9uf,may not be correct,im still looking for the old caps,to verify the are the same type,like for like,as wilmslow may have updated that schem,as the speaker evolved with different drivers in it,as i have 100s and 100s of caps from different projects,im just struggling, at this moment to put my hands on them,
Rodman- the difference between using  one and two power amps,i heard my system using two and heard it using one,i dont want to back to one,tow sounds amazing,one sounds ok,im sure you know what i mean,ive been evolving this system for 30 years,i dont want to loose 10 of them,sorry.

"  Meanwhile: take the Wife OUT for some Meshana Skara or Mousaka and help her relax!    Top it off with some Marudnik (are wild berries in season over there?) and make her love you, again!"
30 years of Hifi,  i dont think one meal will cover that....you know how we get!!.but thx for the advise.

imahififan- no short,,the picture shows a little solder splash,where i DE soldered the other x-over cap to check it,but and in that picture the cap lead is not soldered down,but well spotted, that is studying these pics very closely thx.

So guys,it looks like we are running out of ideas,which makes me feel ,like it might be some thing else,as you guys would have picked up on it,

I know this may sound stupid,so when i test a speaker ,at the binding posts,disconnected,i cannot just put the mul/mtr in ohms and check to see what ohms the speaker is/are ??.as thats what ive done for years !!,im sure that when ,infact i know thats what i did when i found a a tweeter blown  and what i did when i re-capped the x-overs and when ever i test a speaker to see what ohms it is,totest its ok ??.

just a little note,when these amps have blown,they have made the same noise both times ,through the speakers,just like a little pop,then the amp goes into alarm,exactly the same sounds,just thought i would through that in there,
when ive tested these speaker in the past,the way i have expalained ,i have never had 0ohms for the mid/high ,im pretty sure of that,im just putting it out there,
Another thing ,because the amp is getting hot{but they do run hot [Arcam Alpha 10Ps} and they are 25 years old,do you think i should give them a re-cap?,will this possibly bring them back into spec and cool down a  little,.Anyway ill get back to my concreting.
cheers guys

ps,just found this in an old book
7.1ohms LEFT MID/HIGH 8+6.4=4+3.2=7.2
6.8ohms LEFT Bass 6.8

7.0ohms RIGHT MID/HIGH 7.5+6.5=3.75+3.25 
6.8 ohms RIGHT Bass 6.8
i must have taken these measurements of the speakers a few years ago,which are different to the measurements that we have now,i know these are the measurements as i only own one pair of bi-wirable speakers

If you measure the resistance across the loudspeaker posts which include connection to the bass driver (or full range) then you will measure some resistance that is greater than 0Ω which is made up of the crossover components and the voice coil resistance of the bass driver only. You are not measuring the impedance of the loudspeaker, in fact an impedance measurement doesn't mean anything unless you know the frequency you are measuring at.

In your configuration you should see open circuit for MF/HF and some resistance across LF. Which you do when the crossover is disconnected from the speaker terminals.
If I understand you correctly it is only when you put the loudspeaker back together that you read 0Ω across the MF/HF. If that is correct then you have a short which is upstream of the crossover i.e. the loudspeaker terminals, connecting wires etc.
If the MF/HF connectors really are a dead short then your amplifier would fail immediately... actually it should go into overcurrent protection but I digress.

Something doesn't add up.

1) You measure 0Ω across the MF/HF terminals of both speakers.

2) When you had everything disconnected you measured open circuit across IP+ & IP-. That is what you would expect.

Knowing that, it should be simple with the crossover disconnected to measure the resistance across the loudspeaker terminals to locate the short. If there's not one then the short was either at the point the wires connected to the crossover or items 1 & 2 listed above are incorrect.

The fact that both speakers measure 0Ω at the MF/HF terminals implies that you're not looking for a stray wire or small solder bridge but a mistake or failure on both speaker inputs. That's why something like connecting the amplifier outputs incorrectly seemed like a likely scenario... although I know you've ruled that out.