Rockford Fosgate Power 650 Mosfet "rejuvification" - Page 2

pgerry · 9th October 2012, 04:42 PM

I was preparing to install the outputs but wanted to make sure the regulators were behaving 1st. The voltage measurement was done to ensure I had bled the caps. I said the measurement was taken before removing B+, what I meant was after. I normally attach a meter while bleeding a power supply to ensure it's truly discharged. I just thought it was odd to see such a discrepancy between the two sides. I'll proceed with one channel and see how it goes.

Thanks

pgerry · 19th October 2012, 07:20 PM

Finally found some time to work on this again. Installed the outputs for one channel (Grey/Green), powered the amp up and all looked fine. injecting a 1k sine wave produced a nice clean output. I moved on to the second channel (White/Blue) and had good results as well. The third and forth (orange/black and yellow/brown) produce no audio output. idle current is at ~2.5 amps. Where should I be looking next?

Perry Babin · 19th October 2012, 08:09 PM

Do you have both positive and negative rail voltage on the output transistors for those channels?

pgerry · 19th October 2012, 08:29 PM

Yes I have -40.9 and 40.7 present for all outputs.

Perry Babin · 19th October 2012, 08:51 PM

Are you sure that you're sending signal to the correct inputs on the amp?

Is the input selector switch in the correct position?

pgerry · 19th October 2012, 09:01 PM

I wondered the same and cleaned / verified the selector switch and ohm'd out the inputs on the DIN input. I do get a sinewave output from the two channels but it's ~1v P-P and at a fixed 1.5 MHz.

pgerry · 20th October 2012, 02:25 PM

Perry - you nailed it. The selector switch has a third position that is normally locked out with the cover installed. I was going past the second position by mistake. I'm going to let it burn in for a while and re-check before closing it up, but so far it looks good. Any other areas on this amp that I should look out for before it goes back in service?

Thanks again for the help Perry & Sean.

19th October 2012, 08:09 PM	#13
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Do you have both positive and negative rail voltage on the output transistors for those channels? __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

19th October 2012, 08:51 PM	#15
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Are you sure that you're sending signal to the correct inputs on the amp? Is the input selector switch in the correct position? __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

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9th October 2012, 04:42 PM	#11
pgerry diyAudio Member Join Date: Sep 2011	I was preparing to install the outputs but wanted to make sure the regulators were behaving 1st. The voltage measurement was done to ensure I had bled the caps. I said the measurement was taken before removing B+, what I meant was after. I normally attach a meter while bleeding a power supply to ensure it's truly discharged. I just thought it was odd to see such a discrepancy between the two sides. I'll proceed with one channel and see how it goes. Thanks

19th October 2012, 07:20 PM	#12
pgerry diyAudio Member Join Date: Sep 2011	Finally found some time to work on this again. Installed the outputs for one channel (Grey/Green), powered the amp up and all looked fine. injecting a 1k sine wave produced a nice clean output. I moved on to the second channel (White/Blue) and had good results as well. The third and forth (orange/black and yellow/brown) produce no audio output. idle current is at ~2.5 amps. Where should I be looking next?

19th October 2012, 08:29 PM	#14
pgerry diyAudio Member Join Date: Sep 2011	Yes I have -40.9 and 40.7 present for all outputs.

19th October 2012, 09:01 PM	#16
pgerry diyAudio Member Join Date: Sep 2011	I wondered the same and cleaned / verified the selector switch and ohm'd out the inputs on the DIN input. I do get a sinewave output from the two channels but it's ~1v P-P and at a fixed 1.5 MHz.

20th October 2012, 02:25 PM	#17
pgerry diyAudio Member Join Date: Sep 2011	Perry - you nailed it. The selector switch has a third position that is normally locked out with the cover installed. I was going past the second position by mistake. I'm going to let it burn in for a while and re-check before closing it up, but so far it looks good. Any other areas on this amp that I should look out for before it goes back in service? Thanks again for the help Perry & Sean.