Rockford Fosgate T30001bd

RockfordFIx

Member
2012-12-03 11:56 am
Hey perry,

I have been repairing a T30001bd and notice that the driver sties are a bit different. They use a driver ic I am not familiar with. I replaced all the fets and rebuilt the driver circuits. I powered up the amp and started looking for the drive signal and only found it on 2 of 4 banks. I started checking the outputs of the uw3706ic and had square wave on one ic and not on the othe. I felt the one with no wave form and it was warm so replaced it from a donate amp. I ordered some new ones yesterday but curiosity was killing me. I powered amp and had square wave but then no square wave on the chip. These are a little different from the t40001bd series.
1. Should the be a drive signal on all 4 banks at the same time?
2. Do you have a schematic?
3. Does the drive signal look different on these compare to the t40001bd
 

RockfordFIx

Member
2012-12-03 11:56 am
I did notice during troubleshooting the driver circuit that using diode chk across pin 1 & 3 of Q400 and Q406 displayed 0.075v. I thought that was weird. I have 3 more to chk so I will compare to the other 3. Someone tried to repair this one before I got it and the tore tje mesha pads then installed the fets again with thermal grease with no clamping. I think they may did more damage than fixed. I replaced the mesh boards some I had and had to cut one in half.

The drive signal looks different compared to the t40001bd. It seemed like the duty cycle was 90% charging up then 10% off if that makes sense
 
Perry I did scope probing this morning trying to find my drive signal with no luck. Interesting enough, the square wave on the output of the gate driver ic would change by cycling the power. I never had 4 drive signal 2 at most and they switch banks after power cycle...kinda weird. So I was looking for the pwm waveform. Is this suppose to be a square wave? Here is the waveform for both ic chips pin 2.
 

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So not sure if that wave form is normal but I expect them to look the same at very least. Correct me if I am wrong. So now I checked pin 7 on U307 and U301 and this what I got. Oh pin 5 on both had a nice triangle wave form.
 

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I powered up the amp with the HV wires connected to see if I have audio. The FETS were operating correctly it seems and the rail voltage equilized. I did notice a 1.3 vdc on the output. I thought this was strange I connected the audio anyways just to check. With 60hz test signal I saw no audio.