Sansui 1000A coupling caps question

gkargreen

Well-Known Member
In the process of restoring this receiver I note that the coupling caps are 0.3 mfd, should I use a 0.33 mike or can I use a 0.25 mike for these? Thanks
 
.3uf 250v are spec (original equip.). Bump them up to .33uf 400V. The time constant for the grid return resistor R/C network won't change. Note that Orange drops will be very large and you may need to get creative with either placement of them or with wiring in original positions. If 600/630v caps are available and smallish in size, use those. They may be less expensive than 400v.

I would advise Grid resistors (10ohm 1/4w) in place of the grounds on each tube @ pin 5 I believe, and Screen Stability resistors (pins 4-8) between the screen supply and each tube. Cut the jumper between each pair of tubes and then install a resistor from pin 1 to pin 4. Move the Screen supply to pin 1 and add a daisy chain piece of wire from pin 1 on the 1st tube to pin 1 on the 2nd tube.

Go to the FISHER Forum Stickies and look up the "Common Parts for FISHER's needed" and find the drawings for this on page 2 or 3 (it may be further back). Both of these mods are the same for FISHER 500/800B & C models and the Sansui1000A. Just placement is different. Then determine 70 to 80 % of maximum dissipation of the output tubes and bias them to within those parameters. It'll put out a few watts less, but your tubes will love it as they are running in a better area of the envelope instead of at the edge or slightly beyond the envelope.

Larry
 
Last edited:
Back
Top Bottom