Rockford Fosgate PUNCH 401S repairing

josesony68 · 4th January 2012, 09:34 PM

Hello everyone, I just got this amp for repair.
The only question I have is:
¿I can replace the four that I have burned mosfet (MTP50N06V) by, the IRF3205?
Is that in my city, the latter are easier to get ....

seankane · 4th January 2012, 09:56 PM

Yes you can replace with IRF3205 but you must change the gate resitors to 47 ohm. Be sure to also replace the 2 pnp and 2 npn drivers next to the pwm (TL494C) marked 1A and 2A.

Before powering the amp check for shorted output fets and if any are found clip them out of the circuit before powering the amp.

Either someone accidentally reversed the polarity, or an output(s) shorted and took out the power supply.

josesony68 · 4th January 2012, 10:08 PM

Yes, something must have happened ...
Okay, also will change the resistance door, but ... drivers, you mean: Q1, Q2, and Q4, Q5, right?
I think I have. Seankane thank you very much.

seankane · 4th January 2012, 11:39 PM

I dont have a schematic so I am not sure of board location. If you could post a close up pic of the board I could circle them for you.

There are 4 driver transistors right near the pwm chip that are grouped together 2 npn's and 2 pnp's they are marked 1A or 1AM and 2A or close.

They are all right by each other.

Perry Babin · 4th January 2012, 11:44 PM

http://www.bcae1.com/temp/rockford%2...%20pc-4331.pdf

seankane · 5th January 2012, 01:06 AM

So after looking at Perry's link yes you are correct.

Replace Q1, Q2, Q4, Q5 These are the drivers that need to be replaced.

Q1 and Q2 are the MMBT3906L marked 2A

Q4 and Q5 are the MMBT3904 LT1 marked 1A or 1AM

If you need anything else dont hesitate to ask.

josesony68 · 5th January 2012, 03:11 PM

Thanks for the info, Seankane, and Perry, too, by the link of the scheme.
This morning I went to the store to buy IRF3205, but had just three, mmmhhm ... I have to wait until next week ..
When I arrive and have everything installed, I will tell you if it works or not working.

seankane · 5th January 2012, 05:39 PM

Did you check the output fets to see if any were shorted before ordering parts?

josesony68 · 5th January 2012, 07:22 PM

Yes, I checked, and well, anyway, I have several reserve units, in my closet, IRF540 and the IRF9540.
The pieces were actually burned, were:
The four power MOSFET,
The three partners electrolytic capacitors, C20, C22, C24 (all, it was rare, but well marked, when checked, though, to be swollen and leaky)
I checked you said transistors (Q1, Q2, Q4, and Q5) and must leak or something, because each one gives me a different value ...
What do you think, can there be, something else wrong?

seankane · 5th January 2012, 07:51 PM

I think your on the right track, lets get the power supply up and running first.

Replace the power supply fets, gate drives, and the 4 drivers. Maybe you should consider replacing the power supply caps as well.

Once the power supply is up and running we can move to the output section.

4th January 2012, 09:34 PM	#1
josesony68 diyAudio Member Join Date: Feb 2011 Location: Caceres	Rockford Fosgate PUNCH 401S repairing Hello everyone, I just got this amp for repair. The only question I have is: ¿I can replace the four that I have burned mosfet (MTP50N06V) by, the IRF3205? Is that in my city, the latter are easier to get ....

4th January 2012, 09:56 PM	#2
seankane diyAudio Member Join Date: May 2010 Location: Washington State	Yes you can replace with IRF3205 but you must change the gate resitors to 47 ohm. Be sure to also replace the 2 pnp and 2 npn drivers next to the pwm (TL494C) marked 1A and 2A. Before powering the amp check for shorted output fets and if any are found clip them out of the circuit before powering the amp. Either someone accidentally reversed the polarity, or an output(s) shorted and took out the power supply. __________________ 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

4th January 2012, 11:39 PM	#4
seankane diyAudio Member Join Date: May 2010 Location: Washington State	I dont have a schematic so I am not sure of board location. If you could post a close up pic of the board I could circle them for you. There are 4 driver transistors right near the pwm chip that are grouped together 2 npn's and 2 pnp's they are marked 1A or 1AM and 2A or close. They are all right by each other. __________________ 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

4th January 2012, 11:44 PM	#5
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	http://www.bcae1.com/temp/rockford%2...%20pc-4331.pdf __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

5th January 2012, 01:06 AM	#6
seankane diyAudio Member Join Date: May 2010 Location: Washington State	So after looking at Perry's link yes you are correct. Replace Q1, Q2, Q4, Q5 These are the drivers that need to be replaced. Q1 and Q2 are the MMBT3906L marked 2A Q4 and Q5 are the MMBT3904 LT1 marked 1A or 1AM If you need anything else dont hesitate to ask. __________________ 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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4th January 2012, 10:08 PM	#3
josesony68 diyAudio Member Join Date: Feb 2011 Location: Caceres	Yes, something must have happened ... Okay, also will change the resistance door, but ... drivers, you mean: Q1, Q2, and Q4, Q5, right? I think I have. Seankane thank you very much.

5th January 2012, 03:11 PM	#7
josesony68 diyAudio Member Join Date: Feb 2011 Location: Caceres	Thanks for the info, Seankane, and Perry, too, by the link of the scheme. This morning I went to the store to buy IRF3205, but had just three, mmmhhm ... I have to wait until next week .. When I arrive and have everything installed, I will tell you if it works or not working.

5th January 2012, 05:39 PM	#8
seankane diyAudio Member Join Date: May 2010 Location: Washington State	Did you check the output fets to see if any were shorted before ordering parts? __________________ 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

5th January 2012, 07:22 PM	#9
josesony68 diyAudio Member Join Date: Feb 2011 Location: Caceres	Yes, I checked, and well, anyway, I have several reserve units, in my closet, IRF540 and the IRF9540. The pieces were actually burned, were: The four power MOSFET, The three partners electrolytic capacitors, C20, C22, C24 (all, it was rare, but well marked, when checked, though, to be swollen and leaky) I checked you said transistors (Q1, Q2, Q4, and Q5) and must leak or something, because each one gives me a different value ... What do you think, can there be, something else wrong?

5th January 2012, 07:51 PM	#10
seankane diyAudio Member Join Date: May 2010 Location: Washington State	I think your on the right track, lets get the power supply up and running first. Replace the power supply fets, gate drives, and the 4 drivers. Maybe you should consider replacing the power supply caps as well. Once the power supply is up and running we can move to the output section. __________________ 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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