Randall schematic

[Valvehead]

Need a scem for a RH300 .

got one?

i have a burned up diode in the ps -- need to know what it is. D5 on the board .

[izzybell2810]

You could try here: http://www.randallamplifiers.com/Forum/index.asp

[Valvehead]

cant find one and cant register there. There something on there like

"You can find a valid VIP code on the WebSite-Watcher Support page! " to register


i cant find vip anything. what a joke.

[oc disorder]

Check this out :-VINTAGE RANDALL 1970 TO 1990
http://home.mindspring.com/~gsunda/index.html
maybe send an inquiry email..

[Twist]

Is this a solid state amp or tube? Are you talking about the bridge rectifer section of the power supply? Voltage and current ratings are all you need to know for a suitable replacement. You can make an educated guess by looking at the main filter caps voltage rating. Watch the polarity when you replace it. Also it may be a Zener diode for the low voltage rails in a SS amp.

[Valvehead]

SS power amp with a 12ax7 in the preamp. Its a hybrid

[Gtr_tech]

Check the op amps and see which v rail is missing. They'll use +/- 15v....my bet is its a zener regulator for one of those rails.

[Valvehead]

there was a burnt disc cap in the ps . However , with all the sec wires disconnected off the trans, i get a little smoke , heat and a burning smell from the Transformer.

short in the trans it looks like !


what would cause this in a SS amp ?

[Enzo]

Same thing as a tube amp - transformer failure. MAy or may not have been caused by excess current draw from some circuit failure.

If you want a schematic why not contact Randall themselves instead of a forum there.

[Twist]

I've got a RH300 here at the shop too with the exact same problem "smoked tranny". Let me know if you have any luck getting a schematic from Randall. They wont give me one unless I'm a dealer or warranty center.
I'm afraid I'm going to be stuck with this one for salvage. I would bet the tranny is about $150 plus shipping.

[Valvehead]

they sent me a RG scem , not a RH , i never went further with it yet , after finding the bad tranny. Email them or i can send you this pdf i have .

I called - $97 + shipping on the trans. They will sell to non-dealers . part # 31110042 for the RH300 "valve" model