Hartke Hum

[Philisvexed]

Evening all, 

Running Hartke 3500 into Hartke 115XL.

Getting a terrible hum from the amp, I've read many suggestions & I think I've proved them all out. 

The hum occurs even with no guitar plugged in. Literally power to amp, lead to cab.  I've tried different leads, different sockets (out of amp) , different jack socket into cab, different kettle leads, scuffed up the earth mount.  No idea!

Can anyone suggest another avenue to try? 

Thanks

[Bill Fitzmaurice]

Whatever is the problem it's inside. It could be anything from power supply caps that are toast to a simple cold solder joint between a component and the PC board. Easy enough to diagnose and fix if you're an experienced tech. If you're not an experienced tech you need to take it to one.

[Phil Starr]

I had a similar problem with mine, it was the power supply capacitors for the pre amp. The construction of the amp makes it an easy one to repair and any competent tech should have little trouble in finding the problem and the parts are widely available. Shouldn't be too expensive.

Unless you understand this stuff I wouldn't advise poking around inside. The power supply caps are there to store charge and they will do this even after the amp is switched off and unplugged. They can give you a nasty and dangerous shock.

[Philisvexed]

Thanks guys, some new areas to investigate. 

Had some experience in my youth with charged caps 😵

[police squad]

yep I had similar with one of mine. It was capacitors but I'm not sure which.

Got it fixed and it was fine