Accidentally fed ipod into preout w/ jumpers in...no preamp now

Linehand

Active Member
So I have another thread going on this unit, but this issue is specific and separate.

I repaired the driver board, re capped the power supply, and was setting bias on the right channel when I got called away (brand new little baby in the house).

Came back and plugged my ipod into the PREOUT 1 with MAIN IN jumpers connected to PREOUT 2 instead of AUX by accident. Powered up, volume down, a couple seconds pass and I've got music left side only. Look at the board real quick and see that I left the right side (F04) fuse open (what an idiot). And why is there music when the volume is down? (double idiot!!)

At this point I can't get music from a signal fed into the aux. I went to MAIN IN with the ipod and I do have sound both channels there, albeit with some low signal warble sound passing through even with volume at 0.

I see the signal passes to F 2623 on the schematic but I can't find it and I'm not sure thats where I should be starting anyway.

I was so close to being done and now back to square one. If anyone has dealt with this please let me know.

Thanks
 
Surprised the weak-a** iPod output could do any damage...

Don't have much to add though. Hope others more electrically knowledgeable than myself will chime in. Good luck with it.
 
Surprised the weak-a** iPod output could do any damage...

Don't have much to add though. Hope others more electrically knowledgeable than myself will chime in. Good luck with it.

I wouldn't think so either. What worries me is the seconds that passed before I had music. Makes me think the signal had to fight the path backwards through the PREOUT back to the MAIN IN. I hope I'm wrong.

The tuning meter works and the Dolby/Power meters show movement when set on Dolby.

What controls the amp signal back to those power meters?
 
Anybody have a suggested starting point?

I wish I had more time to research, any advice would be greatly appreciated.
 
Diode test the transistors (and any diodes along the way for good measure), working from the preouts back through the preamp board. I wouldn't be surprised if one or more has failed open on you.
 
Diode test the transistors (and any diodes along the way for good measure), working from the preouts back through the preamp board. I wouldn't be surprised if one or more has failed open on you.

Thanks Nate
I found the signal path flow through the various boards. Does anyone have test points for the AUX signal? How can I confirm signal is present on the different boards?
 
to blow fuse 4 it would take something like shorting the output . maybe a speaker wire shorted ? .. best test the even numbered outputs .
 
to blow fuse 4 it would take something like shorting the output . maybe a speaker wire shorted ? .. best test the even numbered outputs .

I have both channels when I bypass the preamp and go MAIN IN...

Edit: I had Fuse 4 removed as I was measuring mA across that channel
 
pre out 1 and pre out 2 are one and the same .they connect together so rules out anything there .

So the signal from my iPod (iphone actually) was fed into the preout with MAIN jumpers installed. No big deal I would think, however, I had music playing as if I was feeding direct to MAIN IN. That makes sense seeing as they are bridged.

However, now I have no signal from AUX back to the PREOUT.

I'm tracing out the AUX feed through F2653 to see if I can identify anything failed in the path. If theres a way to test for AUX signal presence at different positions, it would narrow my problem
 
right there on F2653
damp finger tip testing might be safer for now though so long as you dont go near the power supply .
basically you follow signal path between the boards . if it makes a hum on the speaker everything forward of that point is passing a signal .
 
How do I rouse the Sansui Gurus? Anybody local here in SoCal? I got good beer and good tunes on deck... I know LBPete is from Long Beach haha
 
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