Hifonics Goliath G5000D

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Some problems with this huge amp, Hifo GX5000d.

I got this amp defect to repair. All smps mosfets IRFP1405 20x are replaced, and one side of the output mosfets (12x IRFP350LC). Other 12 MOSFETS were OK (measured).

Now, amplifier power supply is normal working @ +200V
Low voltage supply -12/+12V = OK on the opamps.
After startup idle current is 3,5A, and not in protection, speaker relais are activated. Dummyload 4 ohms connected. Seems normal. No noise from smps.

But... no output on the speakerterminals, when connecting 50Hz 4V on the RCA's inputs.

I didn't get the bassremote with it, but I think it should work without.
gain, filter, settings etc. are dubble-checked.
Why...??
:confused::confused:
 
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Schematic is from another brand, it is on a few details the same as the Hifo.

Still working on it, i think there something wrong with one of the 4 driver IC's. It's unknown type, maybe IRS20124s, 14soic.
On pin 1 there is the PWM signal, but at the second right it is lower in amplitude. On the other three it is exactly the same.

An externally hosted image should be here but it was not working when we last tested it.


Is it save to disconnect the half of the amplfier to select the good/bad side? There are two amps in parallel.

Rob.
 
In this amplifier there are two separate amps in parallel, which are connected just after speakerrelais.
So maybe one amp is OK, the other one fails.
But all outputs from the driverboard are suspicious. If I disconnect all stuff after the driverboard I can check it, right? Or is there a better way to check it? There are 25 mosfet-clamps and it is a lot of work to remove the PCB from the case. And a risk for damaging the new mosfets...

I contacted the German distributor for a complete driverboard.
Thanks again Perry.
Rob.
 
These amps (ones with transistors perpendicular to the circuit board) are known for having broken legs on the semiconductors. You'll have to pull the clamps so you can determine if any are broken or weakened. Pay close attention to the amount of force it takes to push the transistor body away from the heatsink (after it breaks free from the insulator). Any that require less force than the others (with the same part number) are likely about to break.

The clamps are not difficult to remove or replace. Post #3:
http://www.diyaudio.com/forums/car-...sistor-clamps.html?postid=1317683#post1317683
 
These huge amps like this scare me. I usually come across amps to repair either through craigslist or friends and occasionally ebay but I doubt even if I found an awesome deal on one of these I would ever pick it up. Being more of a hobbyist than a repair tech I can't imagine slipping with a meter lead and taking out 100 bucks in parts. Kudos to you guys for having the skills and patience to work on these beasts.
 
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