Solid State Amp - EXPLOSION!!!!

  • Thread starter Thread starter Fusioninspace
  • Start date Start date
F

Fusioninspace

New member
I have a Crate DX212 that a friend gave to me for free...
....and for good reason. (This is 25x2W solid state combo amp.)

It has some kind of loose connection that occasionally causes a painfully loud, short-circuity, static kind of noise. I opened up the amp and was able to carefully locate a place that might be causing the problem.

- One of the speaker output lines from the output transformer appears to be the culpret. It comes out of the OT and then goes back into the board using a standard paddle type connector. I pulled the connection, check for loose solder joints on the board. Put it back together, tested it. and everything seemed to be fixed... Unless I started wiggling wires again.. Then the noise would start blasting sporatically. I put a wire tire on the wire to keep tension on it in a position that would keep the connection solid.

That seemed to take care of the problem while it was on the work bench.

So I put everything back together in the cab.... :mad: It didn't seem to make a difference afterall. It still will give me that hellish noise.

Does anyone have any suggestions on what a REAL fix could be? Or what the problem is???
 
Let me give some more info...

When this explosion of sound happens, none of the controls effect the volume, tonal character, etc. You can't even hear the guitar. It's basically seems that something on the tail-end of the amp is taking over.

But you can get it to cut in/out by tapping/banging on the cabinet. And if you're lucky it will stop and then sound wonderfull again.
 
Just a guess (anything is worth a try). Maybe just pull it apart and give it a good blast with air. Could it be just shit/dust in it ?
 
fusion... intermitents are the hardest thing to fix sometimes... and why it can be an expensive repair even though you end up finding very little wrong in most cases... the best way to approach this if you're not afraid of a soldering iron is to open it up... turn the board over and resolder every connection that looks remotely questionable... and that means desoldering and resoldering... dont simply add some solder here and there... or you'll most likely add even more problems... does this amp have an FXloop??? those things are notorious for fkin up...
 
Fusioninspace said:
I have a Crate DX212 that a friend gave to me for free...
....and for good reason. (This is 25x2W solid state combo amp.)

It has some kind of loose connection that occasionally causes a painfully loud, short-circuity, static kind of noise. I opened up the amp and was able to carefully locate a place that might be causing the problem.

- One of the speaker output lines from the output transformer appears to be the culpret. It comes out of the OT and then goes back into the board using a standard paddle type connector. I pulled the connection, check for loose solder joints on the board. Put it back together, tested it. and everything seemed to be fixed... Unless I started wiggling wires again.. Then the noise would start blasting sporatically. I put a wire tire on the wire to keep tension on it in a position that would keep the connection solid.

That seemed to take care of the problem while it was on the work bench.

So I put everything back together in the cab.... :mad: It didn't seem to make a difference afterall. It still will give me that hellish noise.

Does anyone have any suggestions on what a REAL fix could be? Or what the problem is???
Click to expand...

I second the suggestion that the effect loop on the Crate might be related to the problem-I had a Crate amp years ago that would slowly lose almost all of the volume due to the effects loop components. Jumper the in and out jacks with a guitar cable and see if it helps the problem. It sounds like it may be a cold or intermittent circuit board connection though-not an easy thing to discover..:(
Also, I see you are in St. Louis, years ago a local shop would take gear back to the Crate/Audio Centron company and the techs there would repair almost anything he sent their way. I don't know if this was discontinued when Mackie bought the company-but it might be worth a phone call just to check it out.
 
Hey, I appreciate the comments. I was thinking it was going to be a desolder/resolder operation at some point. Bummer.

I'll try calling St. Louis Music and see if they still have a service center up there. I think they still did when LOUD bought them.
 
be sure to use some solder wick or a desoldering tool so you get a fresh solder joint on whatever you resolder.

Also .... sometimes you can use a strong magnifier and you can actually see the fracture around a solder joint but that's something that's easier to see once you've been shown what to look for. In your case ..... just resoldering anything you see that might be bad, as dm suggested, is probably the best bet.
 
Fusioninspace said:
I'll try calling St. Louis Music and see if they still have a service center up there. I think they still did when LOUD bought them.
Click to expand...

they dont have any repair staff anymore.... infact one of those guys ended up in my old job.... pm me if ya want to get ahold of him... oh and there's not output tranny in a solid state amp... what you were playing with was most likely the main supply rails to the output devices...
 
So you found wiggling wires you can cause the problem, and now you are going to re-solder everything? :confused: Why not focus in on the wire that is obviously causing the problem?
 
dementedchord said:
they dont have any repair staff anymore.... infact one of those guys ended up in my old job.... pm me if ya want to get ahold of him... oh and there's not output tranny in a solid state amp... what you were playing with was most likely the main supply rails to the output devices...
Click to expand...

+1 on the no output transformer.

If it's a spade connector (possibly inside a plastic housing) have you tried crimping it with pliers to make it a good, tight fit?

Outlaws said:
So you found wiggling wires you can cause the problem, and now you are going to re-solder everything? :confused: Why not focus in on the wire that is obviously causing the problem?
Click to expand...

I agree. Maybe attack one thing at a time so you can better determine the effect of individual fixes, and so you can reduce the number of new problems that could possibly arise from re-soldering every connection you can find.
 
Outlaws said:
So you found wiggling wires you can cause the problem, and now you are going to re-solder everything? :confused: Why not focus in on the wire that is obviously causing the problem?
Click to expand...

It's actually been on ongoing targeting process. First I thought it was the input jacks - cause I wiggled the the little board they were attached to and that caused the SPLSDIFHELK sound.

So now I have two very nice, high quality replacement jacks. Thank you.

But the sporatic SAODIHFHF sound continued.

Then I discovered the problem was really one of the 18 wires between the pre-amp side and the buttons that control the effects caused the problem. Snip snip, one at a time,. All snipped. Still the DLFHIOEHE sound would pop out occasionally.

Resolder the 18 wires... You're welcomed.

Take out the NEXT circuit board to gain better access to the main amp board. Ah HA! Found the little bastard! (or so I thought). That pesky pink wire from some kind of transformer (But not the output transformer apparently - see a previous post).

If I pulled it to the left and the POIHDFSOH sound would stop. So I simply then attached a wire tie to keep tension on the connection.... It did seem to stop at that point.

Put it all back together....

S:DLKJFDPOEHFS:LKJE F!!!!!!

WTF?

But actually Outlaws, you are correct. I'll now go back and start again at the stupid pink wire and try it again. Desolder/resolder.. This shit is getting old.

But I really like this amp for noodl'n around with. So I guess it's worth it.

Plus it was free. :)
 
Um... I may be grossly mistaken, but I don't think that the DX212 has an output transformer (in fact, I'm pretty sure 99% of solid state amps don't have OTs, period). It kind of sounds like you have an op-amp that may be going bad, or a component somewhere that's grounding out. Unless you're good with an oscilloscope, take it to a repair shop.

Edit: Oops, I see someone already informed you about the OT. What you were looking at was probably the choke.

Edit2: And if you're intent on trying to fix this yourself, please please please be careful. You should not be reaching in and moving wires manually, as the culprit may be a line that has exposed copper on it and you might find yourself on the receiving end of it. A non-conductive probe can be a lifesaver.

Edit3: Also, have you considered that it might be your power transistors?
 
Last edited:
dont sweat the output transistors... i've never seen one go intermittent... cant even envision how it might be possible...
 
dementedchord said:
dont sweat the output transistors... i've never seen one go intermittent... cant even envision how it might be possible...
Click to expand...

Had one on a friend's old VTX whose solder joint kept arcing, giving a horrible sound every time. It's very possible.
 
Friends don't give friends Crate amps. He's not a true friend.:D
 
I really appreciate all the input on my output :rolleyes:

You all have given me some great trouble shooting tools!!!!

It's funny, I googled all over the place and couldn't find anything on diagnosing these solid state amps. Everything I found concerned tube amps only.

Thanks again! I'll keep working on this sucker....
 
That's because there's a lot more that can go wrong with a solid state amp, and they're much harder to diagnose
 
timthetortoise said:
Had one on a friend's old VTX whose solder joint kept arcing, giving a horrible sound every time. It's very possible.
Click to expand...

minor quibble here that wouldn't be the transistors fault... but rather the wiring/connection to the transistor...
 
You must log in or register to reply here.
Back
Top