I’m losing my vision need help with the F2544 on my 8080DB

[w1jim]

In my never ending quest to (apparently) screw things up I need some help from the Sansui gurus.
A few years ago I picked up a working 8080DB that had been mostly restored.
I thought it was rolling off the highs so I decided to recap the F-2544 tone PCB.

While doing this I had an unrelated situation that lead to some serious vision loss.
I’ve still been able to do some repairs but despite using various aides close up work is a real challenge.

So, after working on this simple board I found that when I turn up the bass it’ll go into protection. I suspect something is allowing DC to pass.
BTW - the two transistors are KSC1845EBU (e-c-b).
I don’t know if I installed a cap backwards, jumped a trace or miswired the leads on the board.

Any help would be appreciated!

 

[OBMG74]

Very sorry to hear about your vision.

 

[w1jim]

Very sorry to hear about your vision.

It's a new challenge I never anticipated - but I press on.
I've been able to do some things; I rebuilt the PS PCB on my SX-850 and replaced the transformer and have built some ham radio antennas and cables but it's a slow process.
I just hope I can get the 8080DB resolved. I've redone the case, removing the crappy vinyl and replacing it with wood veneer.

 

[Tom B]

Jim, sorry about your vision issues. My vision is not as good, as age of 75 can cause problems. But I rely on good glasses, magnifying lamp, and real strong Magnifying glasses if needed.
Maybe you can use some acetone and acid brush to clean connection on the board, take more closeups and post, so that I can better see if any points bridged. More closeups on component side can help as well.
Other option would be to get the unit to me in Bklyn, or send me the board, and I'll see what I can do.
Are there any Frankenfests planned for the near future?
Tom

 

[w1jim]

Hi Tom-
Frankenfest is coming up soon - Saturday October 17th in West Boylston.
I have a variety of vision aids that help but there are some distortions that can't be helped.

 

[Robisme]

I haven’t checked the service manual yet, but the two circled areas looks like they may be shorting across traces or solder pads.

 

[Robisme]

So I looked for a picture of the boards and I found one on eBay. Looks like the one towards the middle of the board is supposed to be shorted. It’s all one pad. But the top one looks like one of the traces is broken going to the pad and the parts lead is soldered to the wrong trace. Just outlook from your picture. Hear the pictures from eBay.