a little help with old rockford 800.2 - 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 3rd February 2014, 04:46 PM   #1
tiomilo is offline tiomilo  Costa Rica
diyAudio Member
 
Join Date: Apr 2012
Location: Costa Rica (retired)
Default a little help with old rockford 800.2

hi mighty gurus i'm here asking for your extremely large knowledge. just finish to rebuild a vintage Punch 800.2 new outputs new psu mosfets and few smd resistors and transistors by the book, now is working smoothly idle @ 0.58 amp consumption. but at few minutes getting hot @ 85 c after 5 minutes running at 4 ohm per channel. is this a bias problem or mismatch/ low quality components perhaps ? outputs are combined IRF9640 by Vishay IRF640N by IR thank's in advance.
  Reply With Quote
Old 3rd February 2014, 05:15 PM   #2
timwebb is offline timwebb  United States
diyAudio Member
 
Join Date: Jan 2010
Location: memphis tn
I think this amp have to use 640's the 640n will not function right if I remember right..
  Reply With Quote
Old 3rd February 2014, 07:43 PM   #3
tiomilo is offline tiomilo  Costa Rica
diyAudio Member
 
Join Date: Apr 2012
Location: Costa Rica (retired)
Quote:
Originally Posted by timwebb View Post
I think this amp have to use 640's the 640n will not function right if I remember right..
Interesting ! but have replaced before 640's for 640N and have no issues. maybe they change something. btw anyone knows where i can get those original IRF640 beside eBay ? most of them are fake ones. tyvm.
  Reply With Quote
Old 3rd February 2014, 08:09 PM   #4
86boy is offline 86boy  United States
diyAudio Member
 
Join Date: Jan 2014
Location: Texas
Digikey
http://www.digikey.com/product-search/en?vendor=0&keywords=irf640pbf


Those what you are looking for?
  Reply With Quote
Old 4th February 2014, 04:00 AM   #5
tiomilo is offline tiomilo  Costa Rica
diyAudio Member
 
Join Date: Apr 2012
Location: Costa Rica (retired)
Yes. Thanks a lot

Sent from my GT-I9300 using Tapatalk
  Reply With Quote
Old 4th February 2014, 07:11 AM   #6
diyAudio Member
 
Join Date: Jun 2012
Tim is correct the IRF640N'S will cause problems in Rockford amps..

The IRF640PBF are the ones you want

You can try the following suppliers

Digikey,Mouser, Arrow, Future ect..
  Reply With Quote
Old 4th February 2014, 12:50 PM   #7
diyAudio Member
 
seankane's Avatar
 
Join Date: May 2010
Location: Washington State
I have heard this many times but never experienced it.

I have used 640N and 9640N in amps many times and have had zero issues. There is still amps working that I have repaired years ago with the "N" FET's.

I don't think you would want N and non N in the same channel as I have never tried that.

How did you set the bias?
__________________
Pyramid 52 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
  Reply With Quote
Old 4th February 2014, 03:06 PM   #8
tiomilo is offline tiomilo  Costa Rica
diyAudio Member
 
Join Date: Apr 2012
Location: Costa Rica (retired)
Bias set at .58 amp at idle. Less will cause distorted sound more will fry it all. Already ordered those 640PBF. Will test and report.

Sent from my GT-I9300 using Tapatalk
  Reply With Quote
Old 4th February 2014, 11:23 PM   #9
diyAudio Member
 
Join Date: Feb 2014
Check for bias runaway by turning the amp on COLD and check the B+ current (0.58A is what you said) then let it sit with NO SIGNAL for an hour, then check to see if the B+ current has increased more than COLD. Check to see that the bias tracking transistors on each channel are in contact with the heatsink. I think they are TO-92 devices. If the HOT bias is too high, just set it lower when COLD.

To check the output circuits, measure the efficiency. Run at full power both channels (Pout), measure B+ voltage and current, calculate the input power Pin=V*I.. If the efficiency (Pout/Pin) is more than 60%, your amp is ok.
  Reply With Quote
Old 5th February 2014, 12:44 AM   #10
tiomilo is offline tiomilo  Costa Rica
diyAudio Member
 
Join Date: Apr 2012
Location: Costa Rica (retired)
Ok already changed the 640N and place 640PBF. Cold idle amp decreased to 0.28 running full power for 12 minutes n'd almost burn my hand @89 test amp consumption was , .89 amp hot. If i set lower bias sound at low volume is kinda distorted. All the bias transistors msp A06 and the mspA56. the efficiency test. Less than 50% =\

Sent from my GT-I9300 using Tapatalk
  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
Rockford 800@2 help please joesch1999 Car Audio 5 18th February 2013 11:22 AM
Rockford Fosgate Power 800.4 seankane Car Audio 71 17th January 2012 07:43 PM
Rockford Fosgate 800 a2 mike49504 Car Audio 1 8th July 2011 06:33 PM
Rockford Fosgate 800.2 Brain Fried Car Audio 2 16th April 2010 05:14 PM
Rockford Fosgate Power 800.4 lostamps Car Audio 6 2nd January 2008 12:21 PM


New To Site? Need Help?

All times are GMT. The time now is 11:49 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