Rockford Fosgate Punch 800a2

seankane · 24th June 2011, 06:02 AM

Hello everyone.

I have a Punch 800a2 I recieved in for repair. One channel was fried. I repaired the channel and everything is ok with that.

The problem is the amp does not produce full power to the speakers.

I can turn the volume to full on the head unit and it sounds like it 1/4 of the way up. The sound is clear and clean but like the head unit is on mute.

I suspect something with the cross over potentiometer, when adjusting it sometimes one channel cuts out.

The amp has no issues just has low output, other than that it sounds great.

Any ideas???

Perry Babin · 24th June 2011, 04:34 PM

Do you have another one on hand to compare the levels at various points?

seankane · 25th June 2011, 12:00 AM

Yes I have 3 others laying around.

What did you have in mind??

Perry Babin · 25th June 2011, 05:18 AM

Power up one of the others. Set all gains the same, set the crossovers to full range and drive a sine wave into the good amp.

Measure the AC voltage at the back of the RCA jacks to get a reference AC voltage (confirm the signal level is the same in the defective amp) and measure the AC voltage at various points in the amp.

Compare the reference voltage to the voltage at the input to the amplifiers (capacitors that couple the op-amps to the power amp). If this is PC-2038, the positive terminals of C201 and C303 are the input to the power amp.

Compare to the other amp. If the signal level is lower at that point in the defective amp, the problem is in the preamp section. If the signal level is the same there on both amps, the problem is in the power amplifier sections.

24th June 2011, 06:02 AM	#1
seankane diyAudio Member Join Date: May 2010 Location: Washington State	Rockford Fosgate Punch 800a2 Hello everyone. I have a Punch 800a2 I recieved in for repair. One channel was fried. I repaired the channel and everything is ok with that. The problem is the amp does not produce full power to the speakers. I can turn the volume to full on the head unit and it sounds like it 1/4 of the way up. The sound is clear and clean but like the head unit is on mute. I suspect something with the cross over potentiometer, when adjusting it sometimes one channel cuts out. The amp has no issues just has low output, other than that it sounds great. Any ideas??? __________________ Pyramid 46 Amp Power Supply----Fluke 787 Processmeter----Tektronix 465 Scope----Velleman HPS40 Scope----Soldering Iron----Desoldering Iron----Hejet HJ 500-S Heatgun----DM4070 Digital LCR Meter----Propane Torch

24th June 2011, 04:34 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Do you have another one on hand to compare the levels at various points? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

25th June 2011, 12:00 AM	#3
seankane diyAudio Member Join Date: May 2010 Location: Washington State	Yes I have 3 others laying around. What did you have in mind?? __________________ Pyramid 46 Amp Power Supply----Fluke 787 Processmeter----Tektronix 465 Scope----Velleman HPS40 Scope----Soldering Iron----Desoldering Iron----Hejet HJ 500-S Heatgun----DM4070 Digital LCR Meter----Propane Torch

25th June 2011, 05:18 AM	#4
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Power up one of the others. Set all gains the same, set the crossovers to full range and drive a sine wave into the good amp. Measure the AC voltage at the back of the RCA jacks to get a reference AC voltage (confirm the signal level is the same in the defective amp) and measure the AC voltage at various points in the amp. Compare the reference voltage to the voltage at the input to the amplifiers (capacitors that couple the op-amps to the power amp). If this is PC-2038, the positive terminals of C201 and C303 are the input to the power amp. Compare to the other amp. If the signal level is lower at that point in the defective amp, the problem is in the preamp section. If the signal level is the same there on both amps, the problem is in the power amplifier sections. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

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