tube amp has a heart beat

[rustycar 10+ year member]

well ive ben tring to work the bugs out of an old mic amp mono 2x 6bq5s, 6ca4, 6eu6, 6au6 well it has a heartbeat sounds like 500hz i can get to go away but always comes back any clue???

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[JimJ 5,000+ posts]

What are your voltages doing...

 

[rustycar 10+ year member]

pulsing...

 

[JimJ 5,000+ posts]

Is the rectifier going bad? Sounds like a bad transformer or rectifier circuit...

 

[rustycar 10+ year member]

well its not the rectifier or any of the tubes except the 6eu7 witch i dont have any replacement to test with. i just knoticed the getter on the 6eu7 looks bad hopefully its this tube. i have let the amp play music for a hour with the heartbeat going and the transformers dont get hot????