Hartke 3500 Problem..

[markstuk]

Hi,

My Hartke 3500 has developed a problem in that it works fine when first powered up, but after about 15 minutes of playing the volume drops and starts to distort before finally fading away... It's not the cab or cables (or even the battery in the bass)... This happens whether I use the "valve" preamp or "SS" preamp level..

Any ideas as to what might be the matter.. ? Not my week for amps so far (My Geodyne is away for repair as well)..

Cheers


Mark

[icastle]

[quote name='markstuk' post='1060630' date='Dec 16 2010, 02:58 PM']Any ideas as to what might be the matter.. ? Not my week for amps so far (My Geodyne is away for repair as well)..[/quote]

My HA3000 had exactly the same problem.
I tracked it down to a dry joint on the preamp PCB.

[markstuk]

Cheers... I'll take a look....

[icastle]

[quote name='markstuk' post='1060639' date='Dec 16 2010, 03:09 PM']Cheers... I'll take a look....[/quote]

No problem.
When mine did this I found that, once the amp had distorted and the volume had dipped, I could bring it back to life by gently tapping the front panel. That gave me a localised area to look for dry joints in.

Not sure if Hartke had a bad day when they built my amp but there were upwards of 50 'dubious' looking joints on that board!

[Slipperydick]

Dry joints are a common problem with the apparently, last thing you need with a bass amp. Does giving it a whack make any difference ? Tried tapping around the PCBs with the handle of a screwdrver ? [i]But only if your electrically capable of it and know what your doing of course, there are dangerous votages[/i], and with one hand firmly in your pocket, so it dont get earthed to the chassis.

Thankfully, mines been trouble free for about 5 years, except for the noisy fan anyway.

[Phil Starr]

probably safer than bashing away at components (though I do this too) is to use a can of freezer spray, which will also help to locate any faulty components.

[markstuk]

Having taken the lid off, and prodded and tightened various bits on the preamp board, it seems to have fixed itself..

Thanks for all the advice.. I'll get it looked at properly in the new year.. thanks for all the great advice guys..

[thinman]

A look around at the solder-side with a magnifying glass might show up the offender. Dry joints sometimes look more dull or "wrinkly". You may also see cracks in a joint that way (not saying that's your problem - they tend to lead to crackles and intermittent problems).

[icastle]

[quote name='thinman' post='1064002' date='Dec 19 2010, 09:13 PM']Dry joints sometimes look more dull or "wrinkly".[/quote]

You callin' me a dry joint?

[thinman]

[quote name='icastle' post='1064030' date='Dec 19 2010, 09:32 PM']You callin' me a dry joint? [/quote]

You just need to moisten your Rizzlas.