Ampeg issues

Fullmetal · #1 11-09-2010, 09:29 AM

I bought an Ampeg SVT-3 Pro a few months back and it has been a dream amp. Perfect for what I play, nice, small and rack-mountable. However, I have had a few issues with the amp recently.

It got dropped outside the practice studio as I was taking it inside about 3 weeks ago. It hit the concrete floor, but the outside wasn't damaged at all. The amp played fine but I noticed a few bits of clipping here and there until at the end of the session the voltage seemed to spike and the amp roared for a few seconds. It hasn't happened since then.

The next practice, the amps volume was pulsing up and down constantly, I had to change to the studio's amp halfway through. Now I've just plugged it in to play, and the volume isn't dipping but the amp is now picking up radio signals.

Every week I seem to get a new problem, does anyone know what might be wrong with it?

-FMJ

jastacey · #2 11-09-2010, 09:35 AM

I'd first would change out the preamp tubes, one by one, and see if issue goes away,then if it still does it, do the same in the drive section, if that doesn't do it then it's time for a tech to trouble shoot it

stiles72 · #3 11-09-2010, 09:36 AM

It could be that the mosfet bias is now off from being dropped, could be a damaged tube, or it could be something else. I'd start with swapping tubes if you have some spares, but if it's anything beyond that you'll want to take it in and have it checked out by a qualified tech.

JimmyM · #4 11-09-2010, 10:00 AM

good answers. mirrors what i would have said.

anderbass · #5 11-09-2010, 01:37 PM

Quote:

Originally Posted by Fullmetal

Now I've just plugged it in to play, and the volume isn't dipping but the amp is now picking up radio signals.

A couple really easy things you could try is a different guitar cord and make sure the outer nut that secures your amps input jack is tight.

If your volume starts 'dipping' again: try patching a guitar cord in-between your Effects Send and Return jacks. If this instantly corrects the problem you've just got dirty switching contacts in your return jack.

Fullmetal · #6 11-11-2010, 01:18 PM

Thanks for the advice. I'll definately try and get some replacement tubes, but if that fails what could the problem be? I'm gunna try and get hold of a tech in a few days anyways, but if I know what the problem is then it saves the guy some time.

Thanks again

Mojo-Man · #7 11-11-2010, 01:54 PM

As an Ampeg user for over twenty years.
My biggest issue is the fact they stopped making product in the
USA.
Also, discontued the V4BH, B15R, B50R.
They stopped listening to there market.

Jim C · #8 11-11-2010, 04:48 PM

All good thoughts; also a history of bad / weak solder traces; I think input jack mount to PC board as well
You might want to search; this has been discussed thoroughly with suggestions from former Ampeg guru Gerold

craig.p · #9 11-11-2010, 05:06 PM

You could also have one or more cracked etches on a circuit board, or a solder connection has come loose. A tech would troubleshoot the problem by connecting a steady signal to the amp input, connecting a speaker to the amp output, and pressing on things inside the amp until he hears what you're hearing. You can do the same thing with anything nonmetallic like a chopstick. But there's limited value to your doing it because even if you do find the trouble spot, are you going to be able to repair an etch?

BigOldHarry · #10 11-11-2010, 05:08 PM

Dropping amps = bad.

Not only tubes, but contacts between boards can get tweaked. If this amp uses surface-mounted pots for controls, you may have *real* real trouble coming...

craig.p · #11 11-11-2010, 05:09 PM

Sorry, Jim. Was typing while you were already done w/ yours....

BassmanPaul · #12 11-11-2010, 05:55 PM

If you bought it just a couple of months ago it should have a warranty. If so, take it in for service. The repair might not be covered but then again it might. With SM technology, an amp should be more resilient to falls.

Jerrold Tiers · #13 11-11-2010, 08:44 PM

Quote:

Originally Posted by BassmanPaul

If you bought it just a couple of months ago it should have a warranty. If so, take it in for service. The repair might not be covered but then again it might. With SM technology, an amp should be more resilient to falls.

If it is now surface mount..... well they have certainly changed it. Somehow I doubt it changed that much.........

A drop onto concrete is bad.... high g-forces, lots of chance for troubles.

I suspect possible issues with solder on controls and jacks, mostly, simply because they are the most likely to get stressed.

That is even more so because of the varying sound levels..... The loop jacks deal is perhaps more likely to have been FIXED than caused by a drop, but it's always worth trying, its cheap......

BassmanPaul · #14 11-12-2010, 09:22 AM

Quote:

Originally Posted by Jerrold Tiers

If it is now surface mount..... well they have certainly changed it. Somehow I doubt it changed that much..........

I got the SM from somewhere! Probably a brain fart. In my case that happens way too often!

I still think the OP should take the amp for service before he does something that doubles the cost of his repair bill.

Jerrold Tiers · #15 11-12-2010, 07:33 PM

Quote:

Originally Posted by BassmanPaul

I still think the OP should take the amp for service before he does something that doubles the cost of his repair bill.

Ayyyup...... that's so.