GP3000D-Pro No Output

[pd8731]

It all started yesterday. I was thumpin and all of a sudden the bass would cut out. I turned the CD player off and on and it would turn on again, so I turned it up. It turned off again, so I just figured the amp was getting hot and going into protect.

Today, I went to turn it on... nothing. I turned the CD player off and on, nothing. I thought the trigger wire was bad, so I tested it. I got 12 volts from there. I was also getting good power. I tested the voltage on the RCAs, 4 volts. I checked the impedance of the subs, 1.4 ohms, so they weren't blown. I checked the voltage on the speaker output terminals. 0 volts.

So I got out a single 4 ohm sub and plugged it in instead of my 12s. Nothing. I checked all the settings on my cd player. Made sure everything was set right. I'm getting nothing from the amp. It is set at MASTER like it's supposed to. I tried SLAVE just for the sake of trying everything, and nothing.

All of a sudden, when I was testing all the different cables for a 50th time, the subs kicked on and scared the bejesus out of me. Now, I can't tell if they were playing music, or if they just burped due to something wrong with the amp. It didn't sound loud enough to be a short anywhere. It sounded like it was at the volume I had it turned to.

I was hitting the amp with the bottom (soft) part of my fist a little bit to see if anything was jarred loose. I noticed that the amp would go into protect if I hit it a little bit. I would turn the CD player off and on, and it would be green again. If I hit it just hard enough, red. I'm not hitting the amp very hard, like the force you would use if a TV set was acting up.

The amp never saw less than 12.5 volts, and was treated very well for the time I've had it (about 2 days). I also opened up the amp to see if anything was burnt. Nothing.

If anybody has an idea, please let me know.

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[profundus-sanus 10+ year member]

did you look for loose stuff when you opened it up?

that sounds somewhat like what my mm4000 did when... i say somewhat because i don't think i tried all that stuff.

 

[pd8731]

did you look for loose stuff when you opened it up?
that sounds somewhat like what my mm4000 did when... i say somewhat because i don't think i tried all that stuff.

I don't think anything fell out or is loose. I looked around the amp for anything not secure, not attached, or burnt, and everything seemed kosher. Also, it had been working for about 2 days before it failed.

 

[Earthman 10+ year member]

Kind of seems like the toroid transformer is grounding to the bottom amp plate. Is there usually a tab of material on top of the toroid to prevent this contact?

 

[tapout 5,000+ posts]

I cant help you but I must commend you on a great "help me" thread.

Usually its, "Help, I got no bass, wats wrong?"

 

[PsychoTheRapist 5,000+ posts]

Kind of seems like the toroid transformer is grounding to the bottom amp plate. Is there usually a tab of material on top of the toroid to prevent this contact?

I don't recall a tab on mine, however, one of the rails was super close to the transformer, so I bent it back a little bit to be on the safe side.

Edit: This is the best pic I have of it; said rail is in the top left hand side.

 

[Earthman 10+ year member]

I think we need to consult Chris from db-r. I'm no amp diagnostic tech, but we could be close given the circumstances

 

[Cravingbass123]

I have a gp3000d-pro it rapes!!!!!!!!!!!!!!!!!!!

also yeah when i opened it up when i first bought it, there was a piece of paper floating around unattached in the case i took a pic.

i attached it on the removable plate, placed right above the biggest power things on the board.

 

[pd8731]

Kind of seems like the toroid transformer is grounding to the bottom amp plate. Is there usually a tab of material on top of the toroid to prevent this contact?

Please indicate what the toroid transformer is.

 

[pd8731]

Okay, well I figured out the problem and fixed it. I wiggled and pressed down on everything and found that when I push down on the toroidal transformer, the bass would come back, I couldn't find the individual wire at first that was causing it, so I thought maybe there was a wire going through the board and touching the top plate of the amp, causing a short somewhere.

I found that when I pushed and let go several times the amp would go into protect, so that's why it was doing that when I hit the amp. I eventually found a wire that had become broken at the solder point, so I got out the ol' soldering iron and fixed it. The amp is now sitting away from the box, and cushioned by some t-shirts.

Thanks anyways for the help eurbody. I appreciate it. Here's a pic of the solder point that broke:

 

[dB-r 10+ year member]

DO NOT mount this amp to a sub enclosure.... I have only worked on one of these, and when I took it apart ALL of the mosfets just fell out of the amp. Whoever had installed it must have had it mounted to a sub box with very bad flexing... it broke the legs of every single mosfet, regulator and rectifier. They literally fell out of the amp when I removed the spring clips.

Good deal on spotting the bad solder connection... It happens. Wave soldering machines at factories aren't near as good as human techs with good soldering skills...

Also, that piece of cardboard type paper is supposed to be glued to the bottom cover above the torroid transformers to stop them from rubbing against the metal cover, re-glue it to the bottom cover above those transformers.