Hello all,
I figured I'd try posting here to see if anyone may be able to shed some light on this problem.
About 2 weeks ago, I warmed up the amp on standby for about 7 minutes, and then, when I switched to full power, one of the 1.5k resistors on one of th power tubes cooked.
I quickly powered the amp off, examined the whole amp, which was visibly okay. I replaced the resistor.
The amp powers on okay, and all tubes glow orange as the heaters are getting power and it appears to be in standby mode.
When I power on, no sound! The tubes stay orange like they are in standby but DO NOT switch to the familiar pale blue like a tube should.
Since then, I've checked the the Power Tranny. It's okay. Power readings off all the leads that should have power. The Output Tranny has readable signal on the leads that connect to the tubes. I've tested the whole power board, and did replace two diodes on this board. They weren't bad but they seemed like the wire leads were weak.
I also replaced the 3 22uF/450V (which appear to be listed as 20/450 on the schematic) caps on the board though the originals seem alright. Infinite resistance so it doesn't seem like they are leaky.
The symptoms are the same.
I found two dead diodes on the 2 outer power tubes as can be seen in the schematic. Replaced those. Still nothing.
I've tried new preamp tubes and new power tubes.
Nothing! Still no sound/output.
The amp responds okay in all other respects. The channels switch, and from what I have been able to find following the schematic, all signal flow and components seem okay.
Anyone have suggestions. I'm sure someone besides me would have this figured out in minutes. I know I'm missing something simple or obvious!
Any help would be greatly appreciated!
Thank you very much all!
http://ca.geocities.com/[email protected]/docs/randallrgt100schematic.pdf
I figured I'd try posting here to see if anyone may be able to shed some light on this problem.
About 2 weeks ago, I warmed up the amp on standby for about 7 minutes, and then, when I switched to full power, one of the 1.5k resistors on one of th power tubes cooked.
I quickly powered the amp off, examined the whole amp, which was visibly okay. I replaced the resistor.
The amp powers on okay, and all tubes glow orange as the heaters are getting power and it appears to be in standby mode.
When I power on, no sound! The tubes stay orange like they are in standby but DO NOT switch to the familiar pale blue like a tube should.
Since then, I've checked the the Power Tranny. It's okay. Power readings off all the leads that should have power. The Output Tranny has readable signal on the leads that connect to the tubes. I've tested the whole power board, and did replace two diodes on this board. They weren't bad but they seemed like the wire leads were weak.
I also replaced the 3 22uF/450V (which appear to be listed as 20/450 on the schematic) caps on the board though the originals seem alright. Infinite resistance so it doesn't seem like they are leaky.
The symptoms are the same.
I found two dead diodes on the 2 outer power tubes as can be seen in the schematic. Replaced those. Still nothing.
I've tried new preamp tubes and new power tubes.
Nothing! Still no sound/output.
The amp responds okay in all other respects. The channels switch, and from what I have been able to find following the schematic, all signal flow and components seem okay.
Anyone have suggestions. I'm sure someone besides me would have this figured out in minutes. I know I'm missing something simple or obvious!
Any help would be greatly appreciated!
Thank you very much all!
http://ca.geocities.com/[email protected]/docs/randallrgt100schematic.pdf