Ampeg BA115

[thedude400]

Hello all, newbie here, great site! I just bought a used Ampeg BA115 for pennies on the dollar knowing it had this issue and it would get bad enough I'd have to eventually fix it. Only 1 place locally that fixes amps and he's 3 weeks out and wants $90/hr. With this amp being only worth maybe $300 at best, fully working, I'm in a pickle.

Every so often, not necessarily a consistent amount of time maybe every +/- 3-4 minutes, an extremely loud piercing sound occurs, the amp goes blank for 20-30 seconds and eventually comes back to normal, only to do it again shortly thereafter. The sound is just dreadful but does not seem to be tied in any way to volume, gain, or other controls.

Does this sound like anything in particular to you vets? I'm willing to to try anything and I have help from someone with electronic tools and experience (father). Any help appreciated, thanks!

[52 Bill]

I'm willing to to try anything and I have help from someone with electronic tools and experience (father). Any help appreciated, thanks!

Welcome to the place.

Set the amp up on its' right side and then stand in front of it. With your left hand hold down the amp so that it doesn't move. Plug a guitar cable into the input and hold the open end of the cord in your right hand with your thumb on the tip of the cord. Now using your nose, turn the amp on. Do you hear a buzz coming from the amp speaker? Now let go of the tip of the plug. Does the buzz stop? Only kidding!

When the amp goes into failure mode, do any of the controls have any effect on the noise? Can you cause the noise to start or stop by jarring or thumping the case?

[Enzo]

yeah, ball up your fist and whack the top of it hard, does that trigger this - or for that matter does it trigger any sound ?

[The Dude]

I would also suspect a broken solder connection somewhere. Do as Enzo says and/or just pull the board out and check for cracked solder joints, particularly on anything with a mechanical connection to the chassis- jacks, pots, etc.

[thedude400]

Welcome to the place.

Set the amp up on its' right side and then stand in front of it. With your left hand hold down the amp so that it doesn't move. Plug a guitar cable into the input and hold the open end of the cord in your right hand with your thumb on the tip of the cord. Now using your nose, turn the amp on. Do you hear a buzz coming from the amp speaker? Now let go of the tip of the plug. Does the buzz stop? Only kidding!

When the amp goes into failure mode, do any of the controls have any effect on the noise? Can you cause the noise to start or stop by jarring or thumping the case?

When she blacks out there's no bringing her back until she's ready, like a depressed teenager. I will try thumping it during failure tho and report back.

[thedude400]

yeah, ball up your fist and whack the top of it hard, does that trigger this - or for that matter does it trigger any sound ?

Will engage and report back

[thedude400]

Good info, I will try this and report back as well, thanks.

[thedude400]

This sounds like a fairly similar problem http://music-electronics-forum.com/t11921/

Think it might be worth considering as well?

[52 Bill]

This sounds like a fairly similar problem http://music-electronics-forum.com/t11921/

Think it might be worth considering as well?

Are you asking if we think your problem is the bridge rectifier?

My answer would be no.