Alpine mrv-f300 remote ciruit - diyAudio
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Old 5th May 2010, 12:14 AM   #1
jol50 is offline jol50  United States
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Default Alpine mrv-f300 remote ciruit

This amp had a shorted output I removed, all tested good so I tried to fire it up. Remote does nothing, followed it for a while and what a maze these things are, lots of transistors. So I went back to the 494 and found no power there, traced pin 12 back out to a transistor (A1266) that has 13v and ~6v, leg 2 powers up the 494 (I think). So with restricted power I shorted it and the amp came on normally, or at least I have rail voltage and about 2A total draw or less. Nothing gets hot I could find, LED is dark.

There is a tiny pot right next to this transistor, have no idea what it does is the only one in the amp, has no power to it (when not shorting it to run). Someone had this apart so who knows what happened to it. Also a 16v cap was popped on the 12v input the other is ok. It tests good but bulged and it burned off the trace to it, burned the case ground also.

Going to try replacing that 1266 transistor (after I look it up), just wonder if anyone has a schematic or seen this before. Tested a bunch of those little transistors and none found shorted.
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Old 5th May 2010, 03:33 AM   #2
jol50 is offline jol50  United States
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Well I'll be dipped, I replaced the 1266 and it fired right up. Thought for sure it would be something else.
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Old 6th May 2010, 12:04 AM   #3
jol50 is offline jol50  United States
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What is with this amp the board looks like paper, it is one sided, they didn't even label/number most of the parts? I've not had one of these old mrv, this looks cheap compared to the newer ones after these like my T757, 1002, etc.
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Old 16th May 2010, 08:05 PM   #4
jol50 is offline jol50  United States
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As a follow up on this...

Have very little into this amp but it was very ragged looking. I like to have amps like this around; some good old school quality on the cheap for temp or abusive apps such as my boat or something. Anyway, I scrubbed the sink in hot water and soap and it looks amazingly better. After tossing a used output substitute in it found in another thread here (from an insignia lol), and a used input cap that was blown with a new wire to fix the trace, it worked just fine. (used parts only because its a beater amp I'll not be selling) This must be around 4x50 in today's ratings and it seems to be in that area.

Well I ripped part of my car system out and yep, tossed this in there to run 4 doors temp. It works well so far, it had under 30mv offset except one side bridged had 54 but I'm using it 4ch anyway. Guess I saved it from the landfill, was some work, someone who should never touch amps took took it all apart and lost some screws, stripped them into the wrong holes, etc. I had to redo all the paste due to dust/dirt from being apart. I took my big IB subs out and stuck a 170rms bridged dual on a single 10" in there, wow, what a step down but will do until I make the new baffle.

I don't think I've seen an amp that is more difficult to follow the traces than this, and its thruhole.
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Old 17th May 2010, 03:37 AM   #5
ppia600 is offline ppia600  United States
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I thought the f300 was the crappy newer version than the 757 and the others you mentioned, not an older better version. That would explain the cheezy pcb. Could have sworn we sold those at Circuit City when we were selling alpine. And we had lots of problems with that line, very unreliable even running light loads.
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Old 17th May 2010, 06:33 AM   #6
jol50 is offline jol50  United States
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This is the old V12, the dark-ish silver one. IIRC this is the first MRV that came out after the all the 35xx black amps, with fins on the whole top and one side rounded. Just like this one except mine looks way uglier lol. I don't know about the board most are fairly good, maybe in the smaller amps they used cheaper ones. On the other hand like most of the older alpines I have, some from the 80s, they are still working with little or no repair.

I have a f345, that is the newest one I have that is not a class d. It seems to be built well, has some nicer digital controls on it, and iirc was not their cheap amp line either. I think I know the one you are talking about it is black and fairly new.
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