MRV-F357 schematic diagram? - diyAudio
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Old 7th May 2013, 05:46 PM   #1
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Question MRV-F357 schematic diagram?

Hello all,new to the site and getting into repairing the older alpine v12 amps from the late 90's.Im getting a mrv-f357 amp sent to me from ebay I just purchased for more than I probably should have.I will go into this amp blind if i must but just wondering if anyone out there may of help .
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Old 10th May 2013, 04:31 AM   #2
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Well I got this big v12 in the mail today. I got it because it was broken with 3+4 channels were bad.Maybe a hundred bucks too much to pay for an old alpine.I took it apart and resoldered a few areas around inputs and outputs.To be honest there were no burned or soot marks anywhere which puzzled me big time.Plugged it in after getting it back together and the darn thing works on all channels........go figure!

Curious on how hot these older relics get?this thing gets hot enough to warm my work room.Maybe cause of 10 amp fuses I used for testing?

I guess the schematics are no longer needed,now to install it my car.
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Old 10th May 2013, 05:31 AM   #3
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Location: Northern California
I don't have the schematic but Pacific Coast Parts most likely does if you google search their name on the west coast here. They were always my source for Alpine related materials.
If I recall correctly this is a 5 channel amp is it not? with a separate power supply for the sub channel. If so and its hot you might still need the service manual to check bias alignment of all the channels and power supply voltages just to be on the safe side before pumping it up in your vehicle...hope this helps some..
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Old 10th May 2013, 03:07 PM   #4
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Thank you again for some info.I will check that company out for a schematic.In the works of making my own for this amp at the moment,not as easy as I predicted but worth it to get back into it.I spent 5 hours yesterday checking all traces under digital microscope ,this thing was either well mantained or never used.The inside did have orange amber on some solder points near b+ inputs and on the side of the separate board for the EQ meaning it did get hotter than hells kitchen.The heat from this unit is like an oven,which I surveyed for two and a half hours with five channels under moderate to heavy load(4 speakers 4 ohm each,200 watts rms each,600 rms watts sub single coil 4 ohm).I pushed it only to the half way point on the gains on each channel and it did not get to the point of burning my hand when touched.Sadly I didnt check temp,which I should of.
But here is question for all with big mambo units like this...If I put intake and output fans on it (cut out holes on bottom pan install two 12v 2-1/2inch fans and raise unit with metal legs on all four to let it breath)has anyone else ever gone to the trouble to protect there older amps this way?

Also did research at a local stereo shop and these things ran over 450 bucks new back 1999......ahh the days when I had no money...lol
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Old 10th May 2013, 06:11 PM   #5
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It sounds like your amp is out of alignment possibly, and the bias is too high on channels. This is why I suggest you get the factory service manual and go thru the check out procedure before using the amp. That basic check is always included in the service manual from Alpine, Kenwood, etc..

At idle on a bench nothing inside of this amp should burn you. As for the orange amber stuff that is excess solder flux from the assembly of the amp and usually of no consequence. As a lot of these older Japanese made amps had residual solder flux left on the boards in different places.

Cutting up the amp and adding cooling fans should not be needed. I have seen this done before and besides ruining the looks of the amp, the amp still failed from later on.
Alpine uses several temp sensing devices thru out the amp to protect the amp and shut it down. You will find them mounted on the power toroids, on the sink and in the channels monitoring those areas just to keep the amp protected from high heat situations. With the heat level you describing I am thinking this amp will not run reliably and will thermal cycle on and off if you place much of a demand on it.

I would try to contact PCP and get the service document, and then check the final adjustments section before further use of the amp, and before considering adding wholes and fans to the unit. If its badly out of alignment, or something is actually defective inside of the amp those fans will not stop a future failure of the amp. I have some older Alpine docs but not the one you need, and I have repaired a couple dozen of your exact amp in my past so I do have some limited remembrance of it.The sub channel power supply is a common failure in almost all of them I ever saw...I hope this helps some..


PS a good friend of this forum and its members has come to your rescue and I now have the service manual to send to you. Send me a private mail so I can get you email address to send it to... Thanks Perry, you are the man....

Last edited by 1moreamp; 10th May 2013 at 06:29 PM.
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Old 11th May 2013, 12:36 AM   #6
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Thank you 1moreamp and to Perry.It would be a shame to damage this beautiful amp by cutting the bottom.I have left it in idle for an hour and no heat was detected from it at all,which is good.I have put it to the test today for a four hour playlist off my itunes connected through my computer on the bench.......It did get very warm but did not go into overload protection mode.There was only one problem with one potentiometer being able to free wheel full circle with no stops at either end.It was for 3+4 channels which I will replace.
As for when I removed the board from the heatsink....would cleaning the white paste off the heatsink and off the chips and maybe putting down artic silver be a wise decision to help dispurse the heat better?

The company put so much white paste down it was like they were going to a fire afterwards.
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Old 11th May 2013, 02:57 AM   #7
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DO NOT use arctic silver heatsink compound. it has metals in them and they conduct electricity.< Copper and Silver > You will short the amp to the case using that stuff. Its made solely for CPU's and they are isolated from the metal cooling surfaces. Where as the power devices in this amp are not isolated from the metal tabs in their cases. Use only standard silicon based heatsink compounds which are non electrically conductive...
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Old 11th May 2013, 04:17 AM   #8
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1moreamp I cant thank you enough for the service manual.Thank you Perry for all your help.I will go over all tests before installation.Yeah artic silver may be a big no no being it is metal.I guess they just run hot,I will take temp readings before and after checking and adjusting.I will post temps.
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