Rockford Fosgate T30001BD

[mike49504]

I replaced 8 of the outputs in this amp. Checked the emitter resistors and checked the drivers all seem to test fine.

When i try to power the amp up it draws excessive current. If i unplug the output board and power up just the power supply board it idles fine.

Wondering where i begin to check??

 

[brandes.cm]

Just a thought, after you pull the bad fets powering the amp up before placing good fets in could save some trouble. I have found checking the gate signals prior to populating the output fets has saved me damaging more output fets.

Someone else could tell me if this is logical or not. Sorry it doesn't help your situation right now.

 

[Perry Babin]

Check the driver transistors, diodes and resistors near the small driver transformers. Double-check the outputs also if you find any defective component.

 

[mike49504]

I checked all drivers,all resistors, and diodes near the small power transformers everything is checking good.

 

[Perry Babin]

Did you check the driver transistors to confirm that every one had 2 good junctions (B-C and B-E)?

You may heed to compare what you read on one half of the outputs to what you read on the other half of the outputs.

 

[mike49504]

Perry,

Do you know if one of the 3 legged connectors go here or not. Since the wasent one when i got this amp. But it was worked on before

 

[Perry Babin]

I don't have photos of a 3000 but I think it should be there. Check for continuity between the TC2 component (thermistor) and the 3 pads between Q432 and Q420 on the insulator.

Looking at the ampguts page, it appears that there is one there.
http://diymobileaudio.com/gallery/showphoto.php?photo=6510

 

[mike49504]

Thats what I thought that one goes there. The is continuity. Between the pads and tc2

 

[Perry Babin]

The amp will operate without that jumper but that thermistor won't be able to shut down the amp if those transistors get too hot.

 

[mike49504]

Ok i put a jumper in the amp. But when i try powering it up it goes into thermal mode and drwas excessive current. If i take the board out that i put the jumper on it powers up fine. I checked the outputs i just replaced and also checked the driver for thoose outputs and they all seem to be fine.

Wondering what i should check?

 

[Perry Babin]

Check for continuity between the center leg of the outputs on that insulator and the thermistor. Do any show continuity?

 

[mike49504]

None of the center legs show continuity to the thermister.

But checked another output board in the amp and its showing continuity.

 

[mike49504]

So im guessing this thermister is bad. Do you know what one they are using or one that i can put in this amp?

 

[Perry Babin]

What's the resistance for the one showing continuity?

I doubt that the thermistor is defective.

 

[mike49504]

The one showing continuity is 4.39 ohms

 

[Perry Babin]

The most likely problem is that there is damage to the coating on the traces on the MEHSA insulator. If the coating gets scratched, solder can bridge connections between the traces and the center leg of the transistor (via the tab). When there is continuity between the other legs and a trace on the insulator, it's generally due to a ball of solder that's wedged between the legs and the insulator.

 

[mike49504]

Theres something wrong somewhere else on this board i took the outputs out of the board. And swapped it with a different board and it does the same thing.

Im thinking maybe a bad driver even know they are testing fine.

I will replace the drivers for thoose set of outputs and clean up the solder connections on the board and see what i can come up with

 

[mike49504]

Ok ouputs are new drivers are new everything checks fine but still draws excessive current.

Could the problem be in the power supply??

 

[Perry Babin]

It's unlikely to be a power supply problem unless the power supply shuts down when you remove one of the audio boards.

When you're checking the drivers, are you simply looking for shorted transistors or are you confirming that each transistor has two intact junctions?

 

[mike49504]

I was testing to see if they were shorted. if i only put half the outputs in the amp it will power up fine doesnt matter which 2 banks i put in