Hartke 3500A fault

[Emian]

My Hartke 3500 developed a fault during a gig last night. The sound is fuzzy - like a harsh rattling farty sound. At first I thought I had blown a speaker - but it's not that.

Does this fault sound familiar to anyone? The amp's a few years old - I'm trying to find what it would cost to repair this - and I could use a back-up amp in ghe meantine - or just replace it.

Ian

[Jam]

amp

Did you open it and check for bad solder joints? Its a start

[Enzo]

Yeah, I'd open it up, apply a signal, an listen to it while I poked each part on the board using an insulated tool, like a wooden chopstick. In particular the capacitors.

Also, along the rear edge of the main board is a row of connectors. The transformer leadsa among them. Wiggle those connedtors. ANy loose conections? I have to resolder the male pins on those now and then.

[Emian]

Seems to be heat related

I powered it up this morning - it seemed to work OK. The crackiling/farting came out in the last set - so I started playing it - and after 15 mins - it started crackling again - heat related?

I'll open if up see if I get anything else.

Ian

[Robert M. Martinelli]

If the fault is indeed heat-related ( drifting active component ), the use of a freezing spray might be the fastest way to find/locate the defective component(s). Wait for the problem to occur, then spray the active components one by one with the freezing spray ( Voltage stabilizers, output devices, op-amps in the preamp section, and so on ) having a friend playing notes at the same time ( or using a signal generator if you have one ) until the amp starts to work normally again, then test/replace the component you were spraying the spray on when the amp went back to normality.

Hope this helps

Best regards

Bob

[Emian]

It's the bass

This surprised me....

It's the bass - not the amp. Before I started working on it, I thought I'd better check my back-up amp for tonight's gig.

It did the same thing - I relaced the cord, and tried other basses - and it's the Fender Jazz.

I guess that's good news - that's gotta be easier to fix.

Thanks for taingthe time to reply everyone.

Ian

[Enzo]

Active pickups with a weak battery maybe?