car amp repair question!!!!!!!! - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 10th April 2004, 09:12 PM   #1
sndtch6 is offline sndtch6  United States
diyAudio Member
 
Join Date: Apr 2004
Location: california
Default car amp repair question!!!!!!!!

i am new to this but i have an amp that i am trying to fix and is bugging the heck out of me. it is a Alpine FLEX MRP-F356 amp. 4 ch @ 75W and a sub @ 150W. the problem is that when i hook it up to my car it keeps blowing my fuse now so i hooked it up to a 12v psu in my house, everything connected except the remote. looks fine untill i connect the remote and it draws so much power that my Psu over heats. i checked it and it is going from 12 v to 5 v with a half second delay. it looks like the power supply in the amp. maybe a deac Cap. can any one help me with this?
  Reply With Quote
Old 10th April 2004, 10:26 PM   #2
sss is offline sss  Israel
diyAudio Member
 
sss's Avatar
 
Join Date: Jul 2003
Location: Israel , haifa
Send a message via ICQ to sss
if u are not experienced then fixing car amps will be very difficult to u, anyways dont do those test with the power supply when no fuses connected , probably all amps psu transistors allready dead
  Reply With Quote
Old 10th April 2004, 10:55 PM   #3
ddog is offline ddog  Finland
diyAudio Member
 
Join Date: Oct 2003
Location: Finland
Hi,

look for shorts in PSU part, switcher transistors, transformer, caps etc.

I think it's propably transistors shorted
  Reply With Quote
Old 10th April 2004, 11:13 PM   #4
sndtch6 is offline sndtch6  United States
diyAudio Member
 
Join Date: Apr 2004
Location: california
thanks for telling me that. i didn't even think of the transistors shorting.

also is there a schematic on this model that is public domain, if not it's ok?
  Reply With Quote
Old 11th April 2004, 12:06 AM   #5
Eva is offline Eva  Spain
diyAudio Member
 
Eva's Avatar
 
Join Date: Oct 2003
Location: Near the sea
Send a message via MSN to Eva
Most common causes of that are :

- Shorted transistor(s) in the audio output stages [most usual cause]

- Control circuit of the PSU malfunctioning and causing heavy cross-conduction or transformer saturation [rare]

- Shorted rectifiers in PSU transformer secondary [very rare]
  Reply With Quote
Old 11th April 2004, 03:27 AM   #6
diyAudio Member
 
Join Date: Nov 2002
Location: Michigan, USA
Default Re: car amp repair question!!!!!!!!

Quote:
Originally posted by sndtch6
i am new to this but i have an amp that i am trying to fix and is bugging the heck out of me. it is a Alpine FLEX MRP-F356 amp. 4 ch @ 75W and a sub @ 150W. the problem is that when i hook it up to my car it keeps blowing my fuse now so i hooked it up to a 12v psu in my house, everything connected except the remote. looks fine untill i connect the remote and it draws so much power that my Psu over heats. i checked it and it is going from 12 v to 5 v with a half second delay. it looks like the power supply in the amp. maybe a deac Cap. can any one help me with this?
From what you describe, it makes me think that your output transistors are blown. Possibly (but rarely) the rectifier diodes. Chances are if you open it up, you'll see what's blown. If any of the output transistors are blown in the audio section, I'd recomend replacing them all... ...same goes for power supply tranistors...

-Dan
__________________
-With a bad amp, everything sounds the same. It takes a good amp to tell the difference between true "Artists" and the rest of the "Performers".
  Reply With Quote
Old 11th April 2004, 03:29 AM   #7
sndtch6 is offline sndtch6  United States
diyAudio Member
 
Join Date: Apr 2004
Location: california
thats the thing though is that there is no brown marks or any visual confirmation that anything is blown up of dead
  Reply With Quote
Old 11th April 2004, 03:30 AM   #8
sndtch6 is offline sndtch6  United States
diyAudio Member
 
Join Date: Apr 2004
Location: california
added note, how would i check the transistors to see if they are bad?
  Reply With Quote
Old 11th April 2004, 10:47 AM   #9
sss is offline sss  Israel
diyAudio Member
 
sss's Avatar
 
Join Date: Jul 2003
Location: Israel , haifa
Send a message via ICQ to sss
if u got a multimetter theres an option to check diodes
the transistor is like 2 diodes
NPN- negative - positive - negative
  Reply With Quote
Old 11th April 2004, 01:41 PM   #10
HDTVman is offline HDTVman  United States
diyAudio Member
 
Join Date: Aug 2001
Location: Chicago area
Quote:
Originally posted by sndtch6
thats the thing though is that there is no brown marks or any visual confirmation that anything is blown up of dead

blown power transistors don't show any external marks unless they are plastic case type. these can have the top poped off if they fail violently.

later BZ
__________________
What ever makes the tunes flow
  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
M&K VX-7 repair question GraceBass Subwoofers 5 2nd July 2008 01:23 PM
Headunit repair question spooney Car Audio 1 19th January 2008 04:26 AM
car amplifier repair question.... jesimon Car Audio 19 13th June 2007 09:34 AM
Transformer repair question woody Everything Else 6 19th October 2005 12:09 AM
tv repair question dvd_diyer Everything Else 1 2nd June 2004 07:23 PM


New To Site? Need Help?

All times are GMT. The time now is 05:15 PM.


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