Rockford Fosgate 801s

mike49504 · 17th February 2010, 03:43 PM

I got this amp in this morning for repair. The guy said he hit the heatsink with the power wire and now his sub sticks all the way out when connected.

So i was think it had dc on the outputs. With the outputs in the amp they read shorted. I took the outputs out in the left channel and off the board they all test fine.

I then checked the resistors (51 ohms) they all test fine.

Then i checked the drivers a56 and 06's all test fine.

Problem im having is theres no dc on the outputs but the left channl has low output and is distorted.

Wondering what might cause this

Perry Babin · 17th February 2010, 04:30 PM

Is the right channel working properly?

mike49504 · 17th February 2010, 04:50 PM

Right channel works perfect

brandes.cm · 17th February 2010, 07:00 PM

Have you tried disabling the protection circuits to see if the waveform comes back?

mike49504 · 17th February 2010, 07:26 PM

Do you know what 2 diodes i have to pull in order to disable the protection circuit to see if i can get it to work?

Perry Babin · 17th February 2010, 07:43 PM

D202 and D205. Remove one, check audio, then remove the other.

Did you get your scope back?

mike49504 · 17th February 2010, 08:17 PM

didnt get it back yet i dont know what the heck he is doing

mike49504 · 17th February 2010, 08:25 PM

I removed d202 and 205 still have the same problem low output and distorted on left channel

Perry Babin · 17th February 2010, 08:56 PM

Do you have rail voltage on leg 3 of all of the outputs in the defective channel?

mike49504 · 17th February 2010, 11:15 PM

Yes i have voltage on the 3rd legs of all the outputs 9640's and 640's

I compared the voltages to the right channel and they are the same

17th February 2010, 03:43 PM	#1
mike49504 diyAudio Member Join Date: Sep 2006	Rockford Fosgate 801s I got this amp in this morning for repair. The guy said he hit the heatsink with the power wire and now his sub sticks all the way out when connected. So i was think it had dc on the outputs. With the outputs in the amp they read shorted. I took the outputs out in the left channel and off the board they all test fine. I then checked the resistors (51 ohms) they all test fine. Then i checked the drivers a56 and 06's all test fine. Problem im having is theres no dc on the outputs but the left channl has low output and is distorted. Wondering what might cause this

17th February 2010, 04:30 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Is the right channel working properly? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

17th February 2010, 07:43 PM	#6
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	D202 and D205. Remove one, check audio, then remove the other. Did you get your scope back? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

17th February 2010, 08:56 PM	#9
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Do you have rail voltage on leg 3 of all of the outputs in the defective channel? __________________ 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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17th February 2010, 04:50 PM	#3
mike49504 diyAudio Member Join Date: Sep 2006	Right channel works perfect

17th February 2010, 07:00 PM	#4
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	Have you tried disabling the protection circuits to see if the waveform comes back?

17th February 2010, 07:26 PM	#5
mike49504 diyAudio Member Join Date: Sep 2006	Do you know what 2 diodes i have to pull in order to disable the protection circuit to see if i can get it to work?

17th February 2010, 08:17 PM	#7
mike49504 diyAudio Member Join Date: Sep 2006	didnt get it back yet i dont know what the heck he is doing

17th February 2010, 08:25 PM	#8
mike49504 diyAudio Member Join Date: Sep 2006	I removed d202 and 205 still have the same problem low output and distorted on left channel

17th February 2010, 11:15 PM	#10
mike49504 diyAudio Member Join Date: Sep 2006	Yes i have voltage on the 3rd legs of all the outputs 9640's and 640's I compared the voltages to the right channel and they are the same

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