AR 10pi wiring help

[reza]

Hi all , new member , from the uk , and sorry but asking for help straight away 

Picked up pair of AR10pi that had been stored for some time , the previous owner having passed away so no history on these 

So main speakers needing a refoam so on taking them out inside the first one I see this 

and the other one 

 

so what do I need , why is it missing / completely taken out , not even wires left ? will/ can it work without it ?  

can I buy one if it is presumably needed , which surely it must be , thanks in advance for any help and advice 

Gary

[DavidR]

Looks like a normal crossover for a 10Pi Except for being mounted in reverse of what mine are. I'd say everything looks normal. It appears you have the original 10Pi. Mine are MkII. What do you mean by "it"? You said you removed the woofer - correct?

I posted pictures: > one of the original crossover and one after I recapped them. I used NPE caps but added a small Vishay 1837 PP cap in parallel to the tweeter and midrange caps.

I also included a crossover schematic.

 

[reza]

Thanks for reply , sorry by it I mean the large blue capacitor in the front is only present in one of the speakers and missing in the other

[Aadams]

 

9 hours ago, reza said:

Thanks for reply , sorry by it I mean the large blue capacitor in the front is only present in one of the speakers and missing in the other

I saw that when you posted but felt sure someone with better information would have posted by now.  The diagram shows 5 caps, which appear to be all present in one but the other cab only shows 4 caps while the red wire appears intact and unmolested in both. Are you sure there is not a fifth cap hidden in the 4 cap photo?

 

[DavidR]

Totally overlooked that. Sorry. (I blame the beers again) BUT I was only able to see one picture/cabinet at a time and I totally missed it. A case of what's missing. Evidently someone had no information to offer at all.

What is the value of the blue cap?

What are the values of the metal can on the left/ middle (in front of the transformer) - in both cabinets. I'm guessing the blue is 20uF and the metal can on the left is 100uF.

[reza]

Aadams , wish there was , I did have good look

 

DavidR , thats ok , the can middle left in the one without the blue cap looks to be 100uf

 

the can in the speaker with the blue cap below, which without a mirror and an "endescope" I cant really see , the only thing I can see is the bottom number is different 7547 to  7552 but I cant see the uf

as for the blue cap sorry but cant see the uf either 

 

 

[johnfalc]

I'm guessing that the two caps discussed (blue and silver) are the same capacity and, although physically in different locations, in the same position circuit-wise ... different vendors but equivalent function.  Trace the wires, do they connect to the same places?

Forget that - in looking on a higher resolution screen I see that both have their large aluminum cans in place ... the first one I did not see on my phone.

Edited September 26, 2020 by johnfalc
Correction

[reza]

Cant trace the wires on the blue cap to see if they end up in the same places as one of the speakers doesn't have a blue cap

On the silver cap yes they do 

[DavidR]

6 hours ago, reza said:

, the can middle left in the one without the blue cap looks to be 100uf

That is what I expected. The blue one should be 20uF.

The 100 and 20 caps are for the woofer and depends on what position the woofer level control toggle switch is in as to whether the 20 is in use.

In the picture I posted of the re-capped crossover the 20uF is the large black Mundorf in the middle and the 100uF is the blue Bennic on the right.

The 20uF is easy to add. One lead goes to the end connector (the long ganged connector in the center) with the red wire. The other end connects to the 100uF with the red speaker lead. Your solder point is most likely on the opposite end from what mine is - because your board is reverse of mine.

[DavidR]

Here's a picture of the level control board. Hope it helps.

 

[DavidR]

Hold on! I downloaded your photos and enlarged them. I think I found the missing cap. I can see it is connected to the proper side of the 100uF.

 

[reza]

DavidR, so that small black cap that the writing says + 50V + NP + is the 20uf cap ? I've been in with a torch and a mirror but cant see 20uf written

And on close examination yes it is connected to the 100uf cap and to the end/red lead of the central connector 

So is everything ok ? do I need to do anything 

How come they are so different , the blue 20uf cap being so huge in comparison , has this been a repair job at sometime , cant imagine they would make them so differently 

Serial number is 7235 

I am so so grateful for your help 

[DavidR]

It could be a replacement or simply what they had on the shelf but I'm leaning toward it being a replacement. (Don't go by the physical size)

The other end should connect to the center solder point at the back end where the red wire comes down from the level control board.

Is there a coil connected at the 100/20 cap solder point? The #6 coil in the middle should connect at the 100/20 solder point. I can see the wire heads in that direction.

It's a good thing I'm a British car nut and own two MGBs and know the translations for many words. I know what a 'torch' is. LOL

I would consider a total recap at some point but see how they sound when you pop the woofers back in.

 

[reza]

1 hour ago, DavidR said:

The other end should connect to the center solder point at the back end where the red wire comes down from the level control board.

Is there a coil connected at the 100/20 cap solder point?

It does , and yes Coil 6 is connected to their solder point 

Nice MGB and MGBGT   got to put some wire wheels on the roadster they dont look right without them 

 

I had an MG Midget when I was 20 , great car , had the Morris Minor engine in it but being so light was very nippy , £60 !

 

Thanks again, wouldnt have known where to start without your help

[DavidR]

That B is a beauty. My first car was a 65 B roadster in BRG and had wires. You are right about them being a requirement. I had a set of wire wheels and the entire front and rear suspensions from a 66 BGT but gave them to my brother in law. I'm getting on in years and have decided to sell the red roadster but first I need to swap the engine and trans. The one in the car has a better motor and its an overdrive transmission. I'm keeping the gold GT for now. I bought it new in 1973 shortly after returning from Vietnam. Best car I've ever owned. Always starts the first time.

Glad to have helped. That's why we are here - preservation/restoration of the Classics.

[reza]

57 minutes ago, DavidR said:

Glad to have helped. That's why we are here - preservation/restoration of the Classics.

Pleased you came home safe from Vietnam 

Thanks again

Thought they'd go nicely with my AR turntable  

 

[DavidR]

Nice TT !