Punch 500a2 distorted channel - diyAudio
Go Back   Home > Forums > General Interest > Car Audio

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 12th January 2011, 02:56 AM   #1
chipper is offline chipper  United States
diyAudio Member
 
Join Date: Oct 2008
Location: Los Angeles
Send a message via MSN to chipper Send a message via Yahoo to chipper
Default Punch 500a2 distorted channel

I got a Rockford Fosgate punch 500a2 for $25 it is in near mint condition one channel works great but the other is distorted i thought it was a open source resistor which one looks burnt and three IRF9540's read 0 ohms from gate to drain, source. And two gate resistors read 8 ohms instead of 10 or 11 ohms (norm?). Wondering if i can replace the bad source resistors and and gate resistors and bad three 9540s? Can i leave the original IRF540s in? Since those read normal.
__________________
Feel the PUNCH
  Reply With Quote
Old 12th January 2011, 03:29 AM   #2
chipper is offline chipper  United States
diyAudio Member
 
Join Date: Oct 2008
Location: Los Angeles
Send a message via MSN to chipper Send a message via Yahoo to chipper
And i have a punch 225.2 sitting here with a shot power supply but i checked the output mosfets and theres some good reading IRF9540's sitting in there, wondering if i can use those? and some source resistors? Or would that be a bad idea???
__________________
Feel the PUNCH
  Reply With Quote
Old 12th January 2011, 11:32 AM   #3
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
If this is your own personal amp, you can use used parts to repair it. If it's for a paying customer or for sale, you should use new parts. The replacement parts are going to cost less than $10.

If the gate resistors are not within 5% of the marked value, they should be replaced. If one of the source resistors opened or is well out of tolerance, you'll need to check the protection circuit resistors connected to that resistor.
  Reply With Quote
Old 12th January 2011, 01:49 PM   #4
chipper is offline chipper  United States
diyAudio Member
 
Join Date: Oct 2008
Location: Los Angeles
Send a message via MSN to chipper Send a message via Yahoo to chipper
Quote:
Originally Posted by Perry Babin View Post
If this is your own personal amp, you can use used parts to repair it. If it's for a paying customer or for sale, you should use new parts. The replacement parts are going to cost less than $10.

If the gate resistors are not within 5% of the marked value, they should be replaced. If one of the source resistors opened or is well out of tolerance, you'll need to check the protection circuit resistors connected to that resistor.
Yes this is my person own am that I'm keeping for my collection 15 other amp hehehe.

Yeah, I looked inside because it sounded distorted and one resistor looks like it heated up pretty good. I have new IRF9540's that I got awhile ago from vishay. I want to know if i can leave the original IRF540's there?
__________________
Feel the PUNCH
  Reply With Quote
Old 12th January 2011, 02:30 PM   #5
Dr Zeus is offline Dr Zeus  United States
diyAudio Member
 
Dr Zeus's Avatar
 
Join Date: Oct 2010
I'd remove all the IRF9540s in the bad channel and then put just one new, good 9540 in and replace it's source resistor as well. If the amp is stable with power and plays without the distortion and minimal load through a test speaker then go ahead and put all the new IRF9540s and source resistors in.

For me, its kind of tough to test a slightly out of tollerance 0.10 ohm resistor with my meter so I just replace them. Ive seen a few RF amps where these resistors failed when the outputs fail.
  Reply With Quote
Old 12th January 2011, 04:24 PM   #6
stoke is offline stoke  ominican Republic
diyAudio Member
 
stoke's Avatar
 
Join Date: Mar 2010
i had one amp with almost the same problem but after replaced all the bad transistor, pulldown resistor and gate driver transistor i still get the audio distorted. the opamp look fine, what other things i have to check?
  Reply With Quote
Old 12th January 2011, 04:45 PM   #7
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
chipper:
I'd recommend replacing all of the outputs in the blown channel but since it's your amp, it's your call.

stoke:
start a new thread if you need help. It's too confusing having two active repairs on one thread.
  Reply With Quote
Old 12th January 2011, 07:27 PM   #8
chipper is offline chipper  United States
diyAudio Member
 
Join Date: Oct 2008
Location: Los Angeles
Send a message via MSN to chipper Send a message via Yahoo to chipper
EDIT: I changed the resistors (.1 ohm) and powered up the amp for a minute with bad parts still in and it fried its self down good!! I'm really mad at myself for doing such s stupid thing!!! It blew the MTP75N05HDs and now the gate resistors are reading 40 ohms. I tested the drive circuit and its producing a signal of 4.7 volts. WHAT SHOULD I DO?!?!? I broke a good amp by a dumb mistake!

Okay if i replace the gate resistors, ps fets will it live to power on again?? I need help! (
__________________
Feel the PUNCH
  Reply With Quote
Old 12th January 2011, 07:29 PM   #9
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
What 'bad' parts did you leave in it?
  Reply With Quote
Old 12th January 2011, 07:30 PM   #10
chipper is offline chipper  United States
diyAudio Member
 
Join Date: Oct 2008
Location: Los Angeles
Send a message via MSN to chipper Send a message via Yahoo to chipper
irf9540's and i think the irf540's also went bad. I just want to get it to work again!
__________________
Feel the PUNCH
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
ONKYO AVR401: distorted sound in one channel TB Solid State 4 3rd December 2010 05:55 PM
ppi pc2150 distorted right channel 67elcamino Car Audio 16 29th August 2009 06:46 AM
Distorted left channel - Marantz 2385 jblmar Solid State 2 27th March 2009 05:04 PM
Distorted left channel Proton 520 Amp allank Solid State 1 13th September 2006 01:41 PM
Help!! Right Channel Freq distorted. TPC Tubes / Valves 3 16th January 2003 02:27 PM


New To Site? Need Help?

All times are GMT. The time now is 09:32 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2