Rockford Fosgate Power 800.4

seankane · 6th January 2012, 11:28 PM

I need a schematic for this amp, the board number is PC-3095-A.

Doea anyone have one?

josesony68 · 7th January 2012, 01:00 AM

Sorry, but I do not know if it will or not ....

http://194.204.29.93/rockford/techli..._schematic.pdf

seankane · 7th January 2012, 03:56 AM

Its got to be close enough, thank you very much!!

This amp was stripped and used for parts and I am trying to revive it it.

So far everything is a go but I have one issue.

Q123 and Q110 read OL from gate to source testing with my meter.

Various components were missing and I have replaced alot of SMD components. These are the only two output fets that read this, the rest check out fine.

There must be something open or faulty somewhere just not sure where to look.

Hoping someone can steer me in the right direction.

seankane · 7th January 2012, 05:59 AM

I cannot seem to get the -36.50 vdc off of the left front channel and it wont bias either.

All other channels will bias and produce clean audio except the left front.

josesony68 · 7th January 2012, 09:24 AM

Maybe, I'm not best placed to help you, but I can give you some idea as to help you ..

Q110 and Q123 If (IRF540) you get 0 on the meter, must be short, and you have to replace them.
You should also review, Q121, Q122, and D106, for just in case, they were wrong, or leaking, (is what I would do ...)

I repaired a, 700S and 851X, which are very similar to that you have.

seankane · 7th January 2012, 09:53 AM

Yes thanks for the advice but all those have been changed because they were missing. Every smd diode and transistor in that area is brand new along with all of the outputs. I must have an open or out of tolerance resistor somewhere to get the 36 vdc on the left front bridging terminal.

Not really sure where else to look??

josesony68 · 7th January 2012, 10:59 AM

So .... Have you Q110 and Q123 is also changed? and do you still gives 0 on the meter, after being replaced?
That's odd ..
If these transistors are short, it is normal to have 36v at the output of audio ...
There must be wrong, something more ..
I do not think that tolerance of the resistors is the cause of this failure.
Do not know what else to tell you, sorry.

Perry Babin · 8th January 2012, 12:36 AM

What's the resistance from the gate of Q110 to the emitters of Q121 and Q122?

josesony68 · 8th January 2012, 09:19 AM

I think it's
R135, its value is 20 ohms, tolerance 5% (Format: smd 1206)

seankane · 10th January 2012, 02:12 AM

Quote:

Originally Posted by Perry Babin

What's the resistance from the gate of Q110 to the emitters of Q121 and Q122?

From the gate of Q110 to the emitter of Q121 is 40.1 ohms

From the gate of Q110 to the emitter of Q122 is 40.1 ohms

They are both the same.

One thing to mention its hard to tell because they are so close together but Q100-Q104 all or some of them are getting VERY hot.

Thoughts?

6th January 2012, 11:28 PM	#1
seankane diyAudio Member Join Date: May 2010 Location: Washington State	Rockford Fosgate Power 800.4 I need a schematic for this amp, the board number is PC-3095-A. Doea anyone have one? __________________ 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

7th January 2012, 03:56 AM	#3
seankane diyAudio Member Join Date: May 2010 Location: Washington State	Its got to be close enough, thank you very much!! This amp was stripped and used for parts and I am trying to revive it it. So far everything is a go but I have one issue. Q123 and Q110 read OL from gate to source testing with my meter. Various components were missing and I have replaced alot of SMD components. These are the only two output fets that read this, the rest check out fine. There must be something open or faulty somewhere just not sure where to look. Hoping someone can steer me in the right direction. __________________ 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

7th January 2012, 05:59 AM	#4
seankane diyAudio Member Join Date: May 2010 Location: Washington State	I cannot seem to get the -36.50 vdc off of the left front channel and it wont bias either. All other channels will bias and produce clean audio except the left front. __________________ 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

7th January 2012, 09:53 AM	#6
seankane diyAudio Member Join Date: May 2010 Location: Washington State	Yes thanks for the advice but all those have been changed because they were missing. Every smd diode and transistor in that area is brand new along with all of the outputs. I must have an open or out of tolerance resistor somewhere to get the 36 vdc on the left front bridging terminal. Not really sure where else to look?? __________________ 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 January 2012, 12:36 AM	#8
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	What's the resistance from the gate of Q110 to the emitters of Q121 and Q122? __________________ 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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7th January 2012, 01:00 AM	#2
josesony68 diyAudio Member Join Date: Feb 2011 Location: Caceres	Sorry, but I do not know if it will or not .... http://194.204.29.93/rockford/techli..._schematic.pdf

7th January 2012, 09:24 AM	#5
josesony68 diyAudio Member Join Date: Feb 2011 Location: Caceres	Maybe, I'm not best placed to help you, but I can give you some idea as to help you .. Q110 and Q123 If (IRF540) you get 0 on the meter, must be short, and you have to replace them. You should also review, Q121, Q122, and D106, for just in case, they were wrong, or leaking, (is what I would do ...) I repaired a, 700S and 851X, which are very similar to that you have.

7th January 2012, 10:59 AM	#7
josesony68 diyAudio Member Join Date: Feb 2011 Location: Caceres	So .... Have you Q110 and Q123 is also changed? and do you still gives 0 on the meter, after being replaced? That's odd .. If these transistors are short, it is normal to have 36v at the output of audio ... There must be wrong, something more .. I do not think that tolerance of the resistors is the cause of this failure. Do not know what else to tell you, sorry.

8th January 2012, 09:19 AM	#9
josesony68 diyAudio Member Join Date: Feb 2011 Location: Caceres	I think it's R135, its value is 20 ohms, tolerance 5% (Format: smd 1206)

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