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Old 26th August 2009, 03:06 PM   #1
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Default Help fixing Alpine MRV 1507

Hi all, im new to this forum. hoping someone can help me with my amp.

I recently bought a blown Alpine MRV 1507 amplifier. i found out that the MOSFETs had blown so i have changed them and put new ones in. Powered up the amp, the light come on but the amp doesnt seem to be getting enough power. It keeps going into safe mode for some reason. I have checked inside again and one off the two transformers look to be burnt but i didnt think it was totally gone. Any one got any ideas of how i can check for sure that the transformer is the problem and where i can get a replacement for it? or if anyone has any service manuals for this amplifier?

any help will be appreciated.
Thanks in advance
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Old 27th August 2009, 09:41 AM   #2
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anyone?
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Old 27th August 2009, 05:42 PM   #3
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Email me if you need the service manual.

babin_perry@yahoo.com

Did you check or replace any of the output transistors (IRF540s and IRF9540s)?
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Old 27th August 2009, 07:25 PM   #4
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no mate i only replaced the blown IRFZ48N. which ones are the output transistors?

here is a pic of the board:
the area marked in red are the mosfets that were blown and have been changed for new ones
Click the image to open in full size.

Also ive just plugged it up into the car again and the amp powers up but the protection and power light keeps flashing and the music light stays on. Ive checked on the instructions and these are the errors http://www.bcae1.com/temp/1507errorcodes01.gif

Protection light blinking = RCA ground float
Power = poor battery voltage (less than 10v)

I only quickly tested this with the current 8awg wiring, no rca's plugged in and the engine was off.
Would these be causing the problem? or is it something internal still?

Hope you can help... just going to send you an email for the service manual.

Thanks
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Old 27th August 2009, 11:41 PM   #5
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I sent the manual.

The RCA float indicator will blink if you don't have a grounded signal source plugged into the amp.

You should not have had less than 10v on the amp unless it was drawing excessive current (even without having the engine running). When you powered it up, did the interior lights in the vehicle dim and remain dim while the amp was on?

You should be testing this amp with a 15 amp fuse in the B+ line to help protect the transistors in case there are more faults. If it blows the 15 amp fuse at idle (no audio), it's drawing too much current.



The outputs are the heatsink-mounted transistors under the clamps on the other board.
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Old 28th August 2009, 12:16 AM   #6
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thanks i recieved the manual.
so i should re try with the rca's plugged in. Is the 8gauge wire ok to just test with? or do i need to use 4 gauge? i think currently theres a 30amp fuse in the 8 gauge wiring. i did not check the interior light but ill have another go and get some more details.
yes i changed the transistors which are under the clamps in the red box on the picture, but they were IRFZ48N, not the ones you mentioned. The larger ones next to them have not been changed though.

I appreciate your help, ive been asking quite afew people no one really knows what to do :S.

thanks
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Old 28th August 2009, 01:54 AM   #7
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The output transistors are on the other board, not the power supply board (where you replaced the Z48s).

The RCAs don't need to be plugged in to make the amp power up normally.

For initial testing, you could use 14g.

The 30 amp fuse will offer some protection but when testing an amp that very likely has problems, I like to use a much smaller fuse or a current limiter.

The large components next to the Z48s are rectifiers, not transistors.
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Old 28th August 2009, 09:32 AM   #8
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oh right, are they also under clamps like the z48s on the other board? look similar to them aswell?
i did have a look at them but they did not seem to be blown. whats the best way to test these?

thanks
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Old 28th August 2009, 11:32 AM   #9
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With your meter set to ohms, you should not read anything near 0 ohms when the probes are touched to the terminals of any individual transistor in any configuration. If any are shorted (~0 ohms between any 2 legs of any individual transistor), they will likely be shorted from leg 2 to leg 3 but you should check 1-2, 1-3 and 2-3.
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Old 28th August 2009, 02:06 PM   #10
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ive just checked them with the meter set to measure 50-2k ohms and yes they show 0 ohms and when i checked the others on the board they all seem to have some resistance. so these would be the next stage to fix?
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