Alpine mrd-m1005 schematics for repair

Mr.Monkeys · 25th August 2009, 05:49 AM

Hi everyone,

This amps been sitting around ever since it stopped working for me awhile back and i'm finally going to attempt to fix it. It turns on and powers up fine from what i can tell, but there is no output for sound. I believe i have replaced the output transistors because one of them were bad in-circuit and off board. At least i think they are the output transistors (c3421). replaced them but still nothing, and when i check one of them in-circuit the reading on the multimeter from base to collector is ~.4 not sure if its suppose to like that, off circuit it measures .584 after its been on the board and it measured .598 before it ever touched the board. Is there something else i need to check? Sorry, i'm just giving this a try because i like to try to fix things. Does anyone have the schematics?

Also i don't know if this problem is related, but none of the changes done to the filters, subsonic, lp etc, will show a change on the digital lcd, like when i change the crossover hz, it stays the same on the display.

robbysankar · 22nd March 2011, 07:16 PM

alpine mrd-m1001 lcd displays when powered up but no rail voltage present.

Perry Babin · 22nd March 2011, 07:52 PM

Email me if you need the service manual.

babin_perry@yahoo.com

robbysankar · 8th April 2011, 09:01 PM

thanks for the info mr Babin.Turns out the ground wire came loose and touched the chassis. this in turn took a few diodes out.with the schematic i was able to replace them and got it going again.

P.S sorry for the late reply.

25th August 2009, 05:49 AM	#1
Mr.Monkeys diyAudio Member Join Date: Aug 2009	Alpine mrd-m1005 schematics for repair Hi everyone, This amps been sitting around ever since it stopped working for me awhile back and i'm finally going to attempt to fix it. It turns on and powers up fine from what i can tell, but there is no output for sound. I believe i have replaced the output transistors because one of them were bad in-circuit and off board. At least i think they are the output transistors (c3421). replaced them but still nothing, and when i check one of them in-circuit the reading on the multimeter from base to collector is ~.4 not sure if its suppose to like that, off circuit it measures .584 after its been on the board and it measured .598 before it ever touched the board. Is there something else i need to check? Sorry, i'm just giving this a try because i like to try to fix things. Does anyone have the schematics? Also i don't know if this problem is related, but none of the changes done to the filters, subsonic, lp etc, will show a change on the digital lcd, like when i change the crossover hz, it stays the same on the display.

22nd March 2011, 07:52 PM	#3
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Email me if you need the service manual. babin_perry@yahoo.com __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

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22nd March 2011, 07:16 PM	#2
robbysankar diyAudio Member Join Date: Dec 2009	alpine mrd-m1001 lcd displays when powered up but no rail voltage present.

8th April 2011, 09:01 PM	#4
robbysankar diyAudio Member Join Date: Dec 2009	thanks for the info mr Babin.Turns out the ground wire came loose and touched the chassis. this in turn took a few diodes out.with the schematic i was able to replace them and got it going again. P.S sorry for the late reply.

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