TFM 45 Rumbling Noise-Help

As few months ago it would cut out once in a while and make this rumbling "brrp brrp brrp brrp" noise (similar to a V-twin motorcycle idling is the best I can describe it) from the speakers . I would turn it off for a few minutes and turn it back on and it would be ok.

Now, all it makes is that noise. If I leave it long for too long, it blows the fuse. Fuse has been replaced.

I opened it up and noticed that one of the power supply diodes was broken in two. I got a replacement and soldered it on. But, that did not solve the problem.

I'd like to exhaust most simple fix options before I consider sending it to Rita's as that will probably cost me pretty penny with shipping etc.

I have 2 X15CBs that have been working great for the past 16 years and am kind of disappointed with the TFM- 45

Any suggestions?

Thanks in advance.

The TFM-45 is a far different beast than a 15. It is a true magnetic field amp, which means it's taking feedback from the amplifier to adjust the voltage and current delivered by the power supply (simplified). Anyway, I would check all your rectifiers. Some are just 4 big diodes (axial) on the circuit board. Some are 4 SIPS. There might even be a big one bolted to the chassis (a D-34 mount).

TFM 45 Rumbling Noise-Help

Whenever I get the rumbles I find that a good dump is in order.

TFM 45 Rumbling Noise-Help

Whenever I get the rumbles I find that a good dump is in order.

+1000 on that!! I know exactly what you mean F1nut.

Thanks BillD. I'll go back and check the rest of the diodes

Good news. Replacing another power diode seems to have fixed the problem!! Yippe Ka Yey! Rumbling has been fixed without having to take a dump. Although, I was going to try that next.Thanks again BillD!