Need tips for recapping Sansui 9090

gto127

Member
2007-05-09 2:51 am
Working on a 9090 with a blown channel & I plan on recapping after repair. Most all caps I tested on this are at 20% over value. Most modern new caps I have tested are from 10% below rated value to 5% over. Will it affect sound to replace with modern cap with slightly less capacitance? Also need to know if I can replace with something audio grade such as Nichicon KW, FW or If need to go with high ripple current caps such as Nichicon PW?
 
I have rebuilt 3 Sansui 9090's, one that had 3 fuses wrapped in tin foil when I opened it up.
I replaced capacitors with the same value as the original but used 105 degree. Get a service manual and check the parts list for fusible resistor locations, replace all of these with new fusible resistors or flame proof resistors of the same value. One of these is more than likely the reason one channel is out.
Replace the speaker relay.

The sound of the amp is determined by the circuit although the new components will be less "noisey" so perceived sound quality can improve.

I really like the power and the sound of the Sansui receivers.
 
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I've always considered the 9090s two main filter caps were a bit on the low side for its rating. That said, you are right on with your observations that the original caps often considerably exceeded their rated capacitance when they were new and still maintain that after 30+ years.

You may find there is absolutely nothing gained in real terms with a wholesale capacitor replacement.

I would also check and clean/replace the speaker relay.
 

gto127

Member
2007-05-09 2:51 am
I got no emails that I had replys to this thread. I have already recapped. Used Nichicon VR for main power and KW for driver board. Left the 2 main caps alone as there was no hum. I also replaced all diodes on driver board in addition to all right side transistors on the output. Receiver sounds good but I am getting very low buzz out both channels when no sound is being played. Could this possibly be caused by Speaker relay?