Rockford Fosgate Punch 800a4

seankane · 8th June 2011, 12:13 AM

Hello everyone.

I recieved a Rockford Punch 800a4 in for repair. 2 channels were completely fried. I rebuilt both channels and all is well, good clean output on the scope and great solid sound.

The problem is when you switch the input switch from 2 channel to 4 channel input the amp makes a loud pop. I replaced the switch with a new switch with same result.

I am wondering if this is normal?? I dont think it should do that. The amp works great but its like something is goofy with the input and crossover switches.

Any ideas would be great...............Thanks again.

ppia600 · 8th June 2011, 12:50 AM

I wouldn't use the switch with the amp on, sounds normal to me.

Perry Babin · 8th June 2011, 03:32 PM

That's generally caused when one of the op-amps has significant DC on its output. Compare the DC voltage on the output terminals of the op-amps feeding the switch.

seankane · 14th June 2011, 10:54 PM

No significant difference, all the op-amps read the same.

Pin 1: 0.635 vdc
Pin 2: 0.735 vdc

Everyone on the board reads the same.

I checked these with no signal present, wondering if I should check them with a signal present????

Perry Babin · 15th June 2011, 05:35 AM

It appears that you don't have the signal source ground connected to the amp's 12v power supply ground. Are they connected?

seankane · 05:50 AM

Signal source unit? I have the head units ground connected to the same ground as the amps ground. These tests were done with no signal present. I re-tested with the rca's (signal) hooked up and the readings were almost all at 0.000 vdc on pins 1 and 7 of all the op-amps. Just a fraction of a volt on a few but no substantial dc, nothing over 0.015 vdc.

Any other ideas of why the switch would pop through the speakers upon being switched from 2 channle to 4 channel input???

Perry Babin · 20th June 2011, 05:54 AM

If the switch is 'break before make', it could be creating an open circuit for a fraction of a second which could cause a tiny bit of instability.

seankane · 20th June 2011, 07:15 AM

Well thats probably what it is cause the old switch and the brand new switch do the same thing. The amp works perfect other than that so I wont sweat it.

Thanks Perry.

8th June 2011, 12:13 AM	#1
seankane diyAudio Member Join Date: May 2010 Location: Washington State	Rockford Fosgate Punch 800a4 Hello everyone. I recieved a Rockford Punch 800a4 in for repair. 2 channels were completely fried. I rebuilt both channels and all is well, good clean output on the scope and great solid sound. The problem is when you switch the input switch from 2 channel to 4 channel input the amp makes a loud pop. I replaced the switch with a new switch with same result. I am wondering if this is normal?? I dont think it should do that. The amp works great but its like something is goofy with the input and crossover switches. Any ideas would be great...............Thanks again. __________________ 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

8th June 2011, 12:50 AM	#2
ppia600 diyAudio Member Join Date: Jun 2007 Location: Louis y ana	I wouldn't use the switch with the amp on, sounds normal to me. __________________ Don't worry... you can always turn the gain down!

8th June 2011, 03:32 PM	#3
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	That's generally caused when one of the op-amps has significant DC on its output. Compare the DC voltage on the output terminals of the op-amps feeding the switch. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

14th June 2011, 10:54 PM	#4
seankane diyAudio Member Join Date: May 2010 Location: Washington State	No significant difference, all the op-amps read the same. Pin 1: 0.635 vdc Pin 2: 0.735 vdc Everyone on the board reads the same. I checked these with no signal present, wondering if I should check them with a signal present???? __________________ 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

15th June 2011, 05:35 AM	#5
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	It appears that you don't have the signal source ground connected to the amp's 12v power supply ground. Are they connected? __________________ 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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20th June 2011, 05:47 AM	#6
seankane diyAudio Member Join Date: May 2010 Location: Washington State	Signal source unit? I have the head units ground connected to the same ground as the amps ground. These tests were done with no signal present. I re-tested with the rca's (signal) hooked up and the readings were almost all at 0.000 vdc on pins 1 and 7 of all the op-amps. Just a fraction of a volt on a few but no substantial dc, nothing over 0.015 vdc. Any other ideas of why the switch would pop through the speakers upon being switched from 2 channle to 4 channel input??? __________________ 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 Last edited by seankane; 20th June 2011 at 05:50 AM.

20th June 2011, 05:54 AM	#7
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If the switch is 'break before make', it could be creating an open circuit for a fraction of a second which could cause a tiny bit of instability. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

20th June 2011, 07:15 AM	#8
seankane diyAudio Member Join Date: May 2010 Location: Washington State	Well thats probably what it is cause the old switch and the brand new switch do the same thing. The amp works perfect other than that so I wont sweat it. Thanks Perry. __________________ 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

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