Sound City PA 50 watt + Mk 4

[blindboybenton]

Hi all

Ive just been given a Sound City PA 50 watt + Mk 4 to repair. Guy brought it from eBay. It has had some very weird wiring mods and some god damn dangerous.

would easier if i had the schematic

Any help !!

john

[pdf64]

Best place for sound city info www.SoundCitySite.com
The bias supply is likely to need a voltage doubler, if one not already fitted.
Beware of the rubbery fabric wire sleeving running along the turret strips; its insulative properties aren't ideal and can allow B+ to leak into grid circuits, via long parallel adjacent wire runs.
Pete

[blindboybenton]

Many thanks

I did hear about the bias issue a few months ago. I think its about -40v. The bias has its own tap from the power tx. Fine for old valves but not for todays stock
Its not fitted. so some investergation will be needed.. Got plenty of time now. As my Day job has just laid everybody off after 7.5yrs of work.. Fixing Mainboards for pc/laptop was not
my thing anyway. Im busy here on the amps. but not enough i think. Time will tell

John