Sansui 7000 return to glory!

AcerPalmatum

New Member
I posted this in another thread, but I think it's more appropriate to seperate this out as it's a maintenance issue.

Today I was lucky enough to score a beautiful Sansui 7000 receiver. I gave it a good clean, polished the timber cover to a brilliant lustre. I check the pots for crackling, but all sound clear. The guy that I bought the unit off said that it had been professionally serviced about three years ago so all good there.
All outputs are working well. Annoyingly most of the button decals have fallen off - replaced with generic labels that are 'adequate' but .....
It does however have a couple of issues.

Firstly, the Aux light seems to be out. The aux function is fine however so I can live with that for the time being.
Secondly, and more importantly, the tuner does not work. It fully lights up, but the signal meters do not move, and zero sound comes out - this is for FM stereo, mono, and AM.

I've just downloaded the service manual for the unit, but to be brutally honest I don't know where to start my investigation. I have some experience with smaller, simpler units, but this is a step up. I am extremely excited to learn though so any help is appreciated.
I don't yet have a scope.... but I can source one quite easily.

Thank you - AP
 
The first place to start with the tuner is the function switch. Give it another round of cleaning. Deoxit D5 may not be strong enough. On switches like this one you can use electrical contact cleaner, just be sure the can says it safe for plastic. Follow up with D5 or G5 (formally pro-gold). If it's still not working, check the power supply for the tuner. Looking at the schematic it looks like the power comes from board F-1317.

Please post the serial number for the database. Click on the link in my signature block.

- Pete
 
The first place to start with the tuner is the function switch. Give it another round of cleaning. Deoxit D5 may not be strong enough. On switches like this one you can use electrical contact cleaner, just be sure the can says it safe for plastic. Follow up with D5 or G5 (formally pro-gold). If it's still not working, check the power supply for the tuner. Looking at the schematic it looks like the power comes from board F-1317.

Please post the serial number for the database. Click on the link in my signature block.

- Pete
Thanks Pete,
I have some Servisol Electronic Cleaning Solvent which might be good for the function switch (unless this is frowned upon?).

I think you might be right about F-1317 being the issue. I get the feeling that the switch is ok seeing as though the tuner meter lamps turn on correctly when switched on. For me it 'feels' as though the board isnt getting powered.

I'll take some photos as I go to document my progress. Thanks for your advice :)

-AP
 
If it's still not working, check the power supply for the tuner. Looking at the schematic it looks like the power comes from board F-1317
I've done an assessment of F-1317 and there are a number of resistors that have completely shorted. The capacitors and transistors seem ok. So I will replace the faulty resistors, and might as well replace the capacitors while I am at it.

-AP
 
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