Rockford Fosgate Punch 200IX

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seankane

seankane

Member
Joined 2010
Ok stay with me this amp seems to be a basket case.

Rebuilt power supply and all is well with that.

4 new IRF3205's, 4 new 47ohm gates, 4 new driver transistors. Amp powers up fine and idles.

L&R channels have recieved all new output fets, all new gate drives, and all new emitter resistors.

R157 and R257 have been replaced.

LM339 reads as follows:

pin 1: 4.41 vdc
pin 2: 4.41 vdc
pin 3: 17.87 vdc
pin 4: 0.188 vdc
pin 5: 2.995 vdc
pin 6: 4.34 vdc
pin 7: 4.99 vdc
pin 8: 4.67 vdc
pin 9: 2.916 vdc
pin10: 4.99 vdc
pin11: 8.21 vdc
pin12: 0.002 vdc
pin13: 4.39 vdc
pin14: 0.080 vdc

Amp produces 75.5vdc rail voltage and all op-amps have -16/+16 vdc on supply pins.

L+ bridging terminal has 16.5 vdc

R- bridging terminal has -2 vdc and bleeds down fast

The left channel wont bias and is very distorted, and the right channel has audio but tries to bias as soon as you try and turn the pot at all.

Q242, Q244, Q245 all have no rail voltage and have +37 vdc on their drains.

243, Q246, Q247 have rail voltage and have -1.950 vdc on their drains and bleeding down fast.

Q143, Q146, Q147 have rail voltage and all have +15 vdc on their drains.

Q142, Q144, Q145 have 1/2 rail voltage and all have +37 vdc on their drains.

I know this is alot of info but thought someone could kick it around looking at a schematic and maybe point me in the right direction to start.
 
Last edited:
seankane

seankane

Member
Joined 2010
Perry Babin said:
Post the voltage on all three terminals of the following transistors. Place the black meter probe on one of the non-bridging speaker terminals. Place the red meter probe on the point where you need to measure the voltage.

Q128
B: -30.75 vdc
C: 0.000 vdc
E: -37.40 vdc

Q129
B: -32 vdc
C: -37.41 vdc
E: -37.41 vdc

Q118
B: +17.10 vdc
C: +75.2 vdc
E: +18.73 vdc

Q119
B: +16.70 vdc
C: +15.15 vdc
E: +17.00 vdc
Click to expand...
 
seankane

seankane

Member
Joined 2010
Perry Babin said:
Post the voltage on all three terminals of the following transistors. Place the black meter probe on one of the non-bridging speaker terminals. Place the red meter probe on the point where you need to measure the voltage.

Q228
B: -34.20 vdc
C: 0.000 vdc
E: -34.72 vdc

Q229
B: -35.36 vdc
C: -37.41 vdc
E: -34.81 vdc

Q218
B: -4.09 vdc
C: +75.2 vdc
E: +1.800 vdc

Q219
B: -4.75 vdc
C: -0.860 vdc
E: +1.950 vdc
Click to expand...
 
seankane

seankane

Member
Joined 2010
Changed Q119 and Q118.

After those I powered up and Q117 and D103 blew.

Changed Q117 and D103 now amp powers up and idles with same issue of 17 vdc on bridging terminal of left channel.

I feel I have made no progress changing out the 2 bad resistors R140 and R170.

After I power the amp up the current draw jumps up a little and I hear like a hissing noise or frequency noise from something in that channel.

I dont know what to think?????
 
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