Hi folks. I'm new to this forum but an old hand at audio electronics repair (30+ years) and I find myself really up against a puzzler with this one.
I have a Fender Frontman 65R guitar amp that produces sputter/static-like noise — intermittently (of course).
Here's some details:
I have not tried opening the feedback loop to isolate where the noise is originating because I don't trust this amp's stability running at open-loop gain. (If there's anyone who has a Frontman 65 and is willing to give it a go I'd be much obliged )
I've done lots of web searching and haven't found anyone with this problem on this amp, so your input and experience would be much appreciated.
I'll attach a schematic for reference.
I have a Fender Frontman 65R guitar amp that produces sputter/static-like noise — intermittently (of course).
Here's some details:
- It's definitely the power amp: I've disconnected the preamp and shorted the input to the power amp and nothing changes.
- It's not thermal: Sometimes it starts immediately on power-up, sometimes it takes several minutes; circuit cooler has no effect, neither making noise better or worse, no matter what components I hit.
- At this point I've replaced every semiconductor device in the power amp (they were all very inexpensive and/or I already had them on hand) except the output transistors.
I have not tried opening the feedback loop to isolate where the noise is originating because I don't trust this amp's stability running at open-loop gain. (If there's anyone who has a Frontman 65 and is willing to give it a go I'd be much obliged )
I've done lots of web searching and haven't found anyone with this problem on this amp, so your input and experience would be much appreciated.
I'll attach a schematic for reference.