SX-1250 service manual is wrong?

[Pageplayer]

I've been plugging away at a 1250 recap the last several weeks when time permits.
(Thanks to MIJ_Pioneer’s most recent BOM List! HERE)

Everything was going very well until a wire broke off on AWM-089 Filter Amp Board that ran from AWG-041 Tone Control board.

I have wire wrap tools and solid core wire in the proper gage to do a factory style fix, but as I was double checking my work to make sure I connected the wires to the correct pins I noticed the service manual is stating some things totally different then what I’m seeing.
For instance, the SM states Pin 14 on AWM-089 should run to AWG-042 pin 4. But,
AWG-042 pin 4 is actually running to AWG-041 pin 8.

So now I’ve confused myself since pins 11 & 14 on AWM-089 do not have wires connected, but the manual says they both should have wires running to pins on AWG-042.

I’m curious if someone already has the actual wiring documented that could share, or could at least verify that I have proper wires connects to AWM-089?

This is basically leading into to my current problem with garbled audio coming out of the left channel.

 

[Watthour]

There are numerous places that the +25V supply connects. It shouldn't matter whether the wire is connected to the specific board/pin shown on the diagram, so long as it receives +25VDC.

Pins 1 or 4 on the AWG-042 could connect to at least 6 places:

AWG-041-3;
AWG-041-4;
AWM-089-13;
AWM-089-14;
AWE-068-35;
AWR-106-10

 

[markthefixer]

AWG-042 pin 4 is a +25v (output) power pass through fed from pin 1 (input) of +25v
while
AWG-041 pin 8 is the tone amp left channel audio output line.

This LOOKS like a screw up (power and audio mixed) - but it should not have left the factory as it would not be working.


The PC board pattern is your ultimate arbiter.

The fundamental theorem of information engineering is that the more improbable the data, the more important it is correct. I hope your pin counts are ok.
My eyes are shot for the day, so I won't be digging in further tonight (i.e. don't wait for more from me tonight)

 

[Pageplayer]

Ok.. I found the issue with the garbled audio coming out of the left channel.. Turned out it was a broken wire at the filter cap terminal.
Everything appears to be operating normally. In fact, it sounds absolutely amazing!
Question tho..
Is the dip in the left filter cap a serious defect or just a cosmetic flaw? It was like that when I received them. Now it's bugging me.

 

[rcs16]

Someone did not do such a good job installing them, possibly stressed the leads when they had to enlarge the ring terminals to fit the larger screws.
I doubt if it is a problem. Looks cosmetic to me. If it shows signs of leakage out the bottom, then it is toast.
If it is really bugging you, measure it out of circuit if you have the test equipment.

 

[Pageplayer]

Oh, Yeah, that someone was me. I recapped this unit.
When I installed the ring terminals I probably broke the solid-core wire when I was twisting and flexing it into place while screwing it to the cap. Should have gave a good tug when done. Another lesson learned.

As far as the dip in the top of the left cap, the values on that cap test like the others. Just bummed it came like that even tho it was wrapped heavily in bubble wrap.

 

[SaturationPt]

If it bugs you, just get it over with and buy another. There's no reason (IMO) to leave any detail like that in a receiver this popular and valuable, IIRC they're only around $25/ea.

 

[Pageplayer]

Agreed.. Just submitted an RMA. Hoping I will be able to exchange for a replacement.

 

[Pageplayer]

Well, Mouser responded to my RMA by simply sending me a replacement. Before swapping it out I decided to take care of another tiny cosmetic issue that was bothering me, and that I've seen on other units, which is small scratches that are starting to rust and faded paint on top of the transformer.



In order to get the screws that hold the cover on, you'd obviously have to remove a lot of wires and I wasn't about to do that.
So, first I used blue painters tape to mask just below and around the top edge. Then I took a blue shop towel, which thankfully don't tear easy, and traced around the top then cut the hole out to slip over the top. I ended up with this.





Pretty happy how it turned out and thought I'd share.

 

[zebulon1]

Nice.