Ibanez TSA5TVR (cute little 5w TV looking amp) with no filament voltage

[drewl]

Cool,
Thanks for the tip and the schem!

[Mars Amp Repair]

Hi Christarak,
I just came across this post and thought I would belatedly add my 2 cents. I am pretty certain it was the rectifier diodes. I have come across this same problem 3-4 times and each time the diodes tested ok with a meter, but replacing them solved the problem. I always used RL201 diodes (2 amp).

Hello folks,
I know these posts are like 3yrs old, but thought I would just confirm that my specimen of this amp was having same filament supply issues, and was the same solution as Amplitech.
After fiddle-farting replacing C50 & C49, I realized the unloaded DC out of the bridge was 7.8Vdc as noted in schematic. It dropped significantly when loaded.
The diodes checked fine on meter diode check as well as on scope junction test. I used 3amp diodes to hopefully preclude the same issue in the future. Probably not necessary & had to drill bigger holes for them to fit but hey, I'm guessing won't have this issue again.
I was going to do some more troubleshooting as the fil voltage was only 5.2v, until I noticed that the circuit is designed to feed the filaments 5Vdc. Thought that was a bit weird, but what the hey.
glen