fosgate t40001bd bad p/s

[bdgf2004]

Should I try this using a sine wave or music?

 

[Perry Babin]

You can use either. Music will be less annoying if you are using a speaker instead of a dummy load.

 

[bdgf2004]

after 30 min on a 4 ohm dummy load playing music it is still producing a clean output. around the corner heatsinks it is running about 110'F and on the straight a ways or along the sides of the amp it's about 100'F. neither of the 2 cooling fans ever turned on (not that i know when they're supposed to). it's about 75'F in the house. my power supply was only dropping to about 12.9v.

 

[Perry Babin]

It doesn't appear that there are any problems. When it blew the last set of outputs that you installed, could you find any reason for it (poorly soldered to the MEHSA insulators, etc)?

 

[bdgf2004]

No. I saw the distortion at the bottom of the output signal at high volume (1 ohm) and then smoke. What do you use to power up and test these huge amps?

 

[Perry Babin]

I rarely work on large amps now. They're simply too much trouble and too time consuming. Just repositioning them is a pain.

When I have to drive them to full power (or at least to high power, some amps are too large to drive to full power), I strap multiple supplies together and sometimes use a battery as well. It's generally not necessary to drive them to full power. If a class D amp works properly driven to clipping into a light load, it's likely OK. Generally, the only problem that causes them to fail when driven into lower loads is when there is insufficient thermal coupling between the transistors and the heatsink.

 

[bdgf2004]

Cool. Ill try it ln my car later.
Thank you so much.
Not only have you saved me money time and time again, I also get a feeling of success and achievment after every repair.
you are the shiznit. (That's a good thing)

 

[bdgf2004]

Tried it in the car... smoke. Doesn't surprise me because of the distortion I saw before. It only lasted about 10 seconds. I hope I turned it off fast enough to save the power supply

 

[Perry Babin]

Confirm that no center leg of any heatsink mounted transistor reads 0 ohms to the heatsink.

 

[bdgf2004]

It appears now that all heatsink mounted fets have shorted, power supply and outputs. Q411,12,13,14,31 center leg is 1 ohm from heatsink. I never replace any of those they were previously replaced by another person.

 

[Perry Babin]

Was the heatsink grounded to the body of the vehicle?

 

[bdgf2004]

No. It was mounted on wood

 

[Perry Babin]

Are you sure that you don't have a bad speaker or bad wiring?

Are the center legs of the outputs shorted to the heatsink as well?

 

[bdgf2004]

The center legs of those 5 fets are directly shorted to the ground terminal and the ground terminal this 1 ohm from the heatsink

 

[bdgf2004]

Im sure that my car setup is good. I use it as a daily driver with the Memphis 4kw you helped me with.

 

[Perry Babin]

Were all of the screws in the board (holding the board to the bottom cover)?

It's strange that the outputs are shorted to ground but I guess that's possible if the rail switching outputs are shorted.

 

[bdgf2004]

Even if I disconnect the 3 jumper wires Between the 2 boards the short is still there.

 

[bdgf2004]

It appears as though one of my mesha strips for the power supply fets is bad. I get about 6m ohms from the back to the front pads.
Would anyone happen to know where I could find some mesha strips.

 

[RockfordFIx]

Can someone send me schematics for a Rockford T40001BD amp to matt76.brooks at gmail dot com

I have replaced the output FETS b/c 10 out of 20 were blown. The powersupply drivers checked out ok. But, i am only getting -110V for -HV output and ~9v for the +HV side. any thoughts.

 

[Mooly]

Can someone send me schematics for a Rockford T40001BD amp to matt76.brooks at gmail dot com[/email]

I have replaced the output FETS b/c 10 out of 20 were blown. The powersupply drivers checked out ok. But, i am only getting -110V for -HV output and ~9v for the +HV side. any thoughts.

You might be better starting a new thread and detailing the tests and checks so far performed.