rockford fosgate t40001bd

[RockfordFIx]

with the black probe on ground I have the following voltages:
red = 3.777vdc
blue = 208 CDC

 

[RockfordFIx]

sorry I changed the variables around. I was able to get a 2nd powersupply board for troubleshooting. what ever the problem is that inhibits the high voltage sharing.

 

[RockfordFIx]

I used probe 2 probes to verify the clock is working correctly. ch1 on pin 2 of the hc74 ch1 on pin 5 the square waves were 180 degrees out of phase which what I expected. the lm5110 for out A and out B are out of phase it seems that amp is functioning properly until rail voltage is applied. if install the light bulb to limit current flow. is it okay to check for drive signal or while that damage the components

 

[Perry Babin]

'Across' means one probe on each of those points, no probe on ground.

For the voltage on the outputs, DC voltage.

1. black probe on ground, red on leg 2 of Q432.

2. Black still on ground and the red on leg 3 of Q426.

 

[Perry Babin]

You can have the light bulb in the circuit for any testing but it will limit the output power. The bulb will help protect the amp but since there are a lot of rail caps after the bulb, it's not foolproof.

 

[RockfordFIx]

hey perry I apologize for the delay. I have the current bbn limiting device inline with the blue wire and the amplifier seems to be stable.
1. black probe on ground, red on leg 2 of Q432. =
24.51vdc

2. Black still on ground and the red on leg 3 of Q426. =

-34.51vdc
__________________

 

[RockfordFIx]

the voltage across the blue and red wire with current limiter installed and audio board connected is:

118.2vdc

 

[RockfordFIx]

perry what I dont understand is with the current the current limiter installed, the voltages are low but they seem to sharing the rail voltage. once remote were is removed the Q432 voltages jump: black probe on ground.
power on:
1 = 3.725
2 = 26.50
3 = 0.001

remote removed:

1 = 0.001
2 = 82.5
3 = 0.001

 

[Perry Babin]

When remote is removed, one bank for the rail/output group clamp for a few seconds. That's one reason that the voltage jumps when you remove the remote signal.

How much voltage is dropping across the limiter.

If it's a lamp, what's the wattage?

 

[RockfordFIx]

I was right with the current limiter installed the amplifier will play audio fine. I have figured outthe problem Perry. the problem was me. Apparently, I have been very impatient and did not let the complete its warmup cycle. Meaning the FETS have high rail voltage until enabled and then begin sharing. this means the board is operating correctly and with your help and for the current limiter on the rail voltage I would not have got passed the mental barrier. Thank you Perry i think I have just gained vital knowledge from this.

 

[RockfordFIx]

the lamp is a 120v 60watt bulb

 

[Perry Babin]

You have a 60w incandescent bulb? The black helicopters will be hovering over your home, any time now.

 

[RockfordFIx]

yes a incandescent bulb, what do you mean by the helicopters will be hovering.

 

[Perry Babin]

It was a joke. The government tried outlawing 60w incandescents to save energy.

 

[RockfordFIx]

well I spoke too soon one audio board is functioning and the other well the bulb just gave me an additional minut or 2 til a bank of FETS popped.

 

[RockfordFIx]

ha.. took me a second. I am glad you still have a sense of humor after all people you help at different levels electronics including myself

 

[Perry Babin]

It's not a sense of humor, it's insanity.

 

[RockfordFIx]

I know the feeling. rebuilding this audio board for 3rd time is the definition of insanity too. I got a t40001bd in the other day with no mesha boards installed and instead they used a mica insulator and blue clamps. it was clean work but they used a different FET. the FET was a IRFP4229 which my curiosity I t
checked the data sheet and it candle 10amps less and wondering If that is why it failed

 

[Perry Babin]

The failure could be due to the current rating. It could also be, in part, due to the roughness of the heatsink. Some are smooth enough. Some need to be sanded but keeping it flat when sanding is another problem. When replacing the MEHSA insulators, it's probably better to use a strip of copper stock (about the same thickness of the MEHSA) as a smooth heat spreader.