testing a crossover

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.