SANSUI 7070 repair

[spaghetti]

Hello, I am trying to repair a Sansui 7070 receiver which has some issue with the AMP board, it won't come out of protection unless the AMP board (F-2624) is removed. I've already located some open/out of spec fuse resistors, all the 180ohm, and I replaced them temporarily with 220 ohm, but nothing changed, still no relay click.

I searched the web for schematics and service manuals, but all of them show black circles instead of readable voltages... guess that is the result of some (very effective!) xerox copy protection. Does anyone has a fresh readable scan of the schematics showing voltages?

Thanks,
Andrea

 

[Tom B]

You may want to check all of the fusable resistors on that Driver board, as many drift way out of tolerance.
I would suggest you get some metal film resistors for the board and replace them all
4.7 ohm 1/4w R35, R36 (you can put in 1/4w or just get all 1/2 watt resistors)
180 ohm 1/4w R33, R34 (you can put in 1/4w or just get all 1/2 watt resistors)
4.7 ohm 1/2w R47, R48, R49, R50
10 ohm 1/2w R39, R40
150 ohm 1/2w R41, R42, R43, R44

And of course check all outputs, drivers and others on the driver board for opens and shorts.

 

[avionic]

guess that is the result of some (very effective!) xerox copy protection.

No . Not copying the original in color. Those blacked out portions are suppose to be orange in color.

 

[spaghetti]

Thanks for the help, I eventually replaced all the fuse resistors, now everything works fine.

 

[avionic]

Super...

 

[Tom B]

Great news. Enjoy that Sansui!!