Scosche vr3 - diyAudio
Go Back   Home > Forums > General Interest > Car Audio
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Thread Tools Search this Thread
Old 4th June 2010, 03:45 AM   #1
diyAudio Member
Join Date: Sep 2006
Default Scosche vr3

Im working on this amp i found 2 bad outputs in it. I removed them from the board and powerd the amp up.

Its producing negative rail voltage. The positive rail voltage starts out at 27 volts then starts decreasing so like i start with 27 volts then it goes to 20 volts then 15 volts all the way down to 3 volts then it starts over agin 27 volts then decreases.

Wondering what might cause this problem and where do i need to check?
  Reply With Quote
Old 4th June 2010, 05:21 AM   #2
diyAudio Member
Join Date: Sep 2006
I did somemore checking and This is what i got for voltages

Power Supply Fets IRFZ44N's
No wave form on gates.

  Reply With Quote
Old 4th June 2010, 10:53 AM   #3
diyAudio Member
Join Date: Nov 2003
Location: Louisiana
It sounds like the power supply is coming up and is sensing a problem so it shuts down. The voltage drops slowly as the filter caps discharge.

I think you have the voltage on 15 and 16 reversed. Re-check that.

The voltage on pin 4 is too high also.

A photo of the inside of the amp would be helpful. I've never worked on one of these.
  Reply With Quote
Old 4th June 2010, 05:04 PM   #4
jol50 is offline jol50  United States
diyAudio Member
Join Date: Nov 2007
DC offset is one thing, otherwise follow the protection circuits back to see what is shutting it down but that is harder to do I usually fire them up with the meter on different things to catch the obvious such as another bad output.

If you see gate voltage to the PS fets and then it goes away its near always protecting. Does it have a protect LED?
  Reply With Quote
Old 4th June 2010, 05:05 PM   #5
diyAudio Member
Join Date: Sep 2006

I had some leaking outputs in this amp with them removed it powers up fine.

The amp is using IRF540's for the outputs. Would ^40's work in this amp also or is that not a good idea?
  Reply With Quote
Old 4th June 2010, 05:09 PM   #6
diyAudio Member
Join Date: Nov 2003
Location: Louisiana

The 640s are rated for significantly less current. They 'may' be OK for testing but I wouldn't use them as replacements.
  Reply With Quote


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
Walmart VR3 12" Subwoofer? form109 Car Audio 18 16th August 2010 02:26 AM
Scosche - Any Good ? EdT Multi-Way 1 24th February 2007 06:01 PM
Scosche SPL meter: Cheap find with potential, or cheap junk? theAnonymous1 Everything Else 5 11th October 2006 03:40 AM
Boston VR3 and VR2 speakers vossie Multi-Way 4 8th October 2004 05:10 PM
Audax HM130CO VR3 Matching HT Project MemphisJim Multi-Way 2 11th June 2004 02:22 AM

New To Site? Need Help?

All times are GMT. The time now is 08:18 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2