Alpine MRV-1000 Fault
I`m having some trouble with my mrv-1000 amplifier from Alpine.
The first problem was that a resistor and 2 caps was wasted, after what a have measured. i replaced the caps for both channel, but, i replaced them with caps that can take upto 25v, because i didnt get 16v`s 3300uF, you can see this at picture SANYO298.
The resistor i couldnt find in the exact resistance and watts, so i actually replaced it by parallell connecting some, who made the same resistance as the resistor for the other channel did, look at pic. SANYO295.
Okey, after this i tought it was fine, i started it up in my room on my recievers preouts, and home speakers. the amplifier worked well, both channel had great sound. so i puted it in my car, and hooked it up there, started it and running about 10-15mins with pretty high music level, and suddently one of the channel says "poff" and i look behind me and i see a wall of smoke. i took it out, and yet again bringing it in to look at the damage, and now one of the transistors is totally blown. look at the picture SANYO299. you can also see that its been really heat around the weldings other places too.
SANYO294 is a picture from underside of the print.
When i runned it in my room, the channel also got abit hotter than the channel without trouble.
Does anyone know what might have gone bad here? i cannot find these transistors in the component shop around here either, is there another name for it?
Before you repair the power supply, you need to check the output transistors. They are on the same side of the amp as the blown transistors. They are labeled Q219, Q221, Q223, Q225. If you measure anything near 0 ohms between the second and third legs, you'll need to pull them ad check them off of the board.
An IRFZ44 is a suitable replacement for the NDP605B.
Hi Perry, thanks for the respons!
I cannot find any transistors labeled Q219, Q221, Q223, Q225 on any place of the print.
on the side where the blown transistors is is following others: 1220A-Y, C2690A-Y, 1220A-Y, A1265N, A1265N, C2682-Y, C3182N, C3182N.
its few versions of the IRFZ44 i found: IRFZ44N/IR, IRFZ44V/IR and IRFZ44R/IR. witch one of these are the correct?
i also found some more wasted resistors that needs to be changed
The 2SA1265Ns and 2SC3182Ns are the outputs. The numbers I posted were the circuit board designations.
I've used IRFZ44Ns in the past and they worked well. The other versions of the IRFZ44 should work also.
You need to check the burned area of the board to determine if it's become conductive. Set your meter to ohms and place both leads on the burned area. The leads need to be placed as close as possible without touching each other. If you read anything other than OL or infinity, you need to cut away the conductive area. Remove the gate resistor for the burned transistor and check the resistance between the burned area and the pad for the gate lead of the transistor. If the resistance is anything other than infinity, you need to cut away the conductive fiberglass between the pads.
Thanks, Perry :=)
i have measured the transistors now, i adjusted the measure meter to 200k ohms, and got these readings:
2SA1265N: 50.0 - 90.0
2SC3182N: 27.0 - 45.0
it changed up and down all the way, might be my measure tool that have been seeing better days.
i also checked the burned area of the board and one of the areas didnt turn out on the measure-meter at all, so i guess i need to do something there.
Does anyone have schematics for this amplifier?
If you don't have an auto-ranging meter, you need to use the lowest range when testing the transistors and the highest range when testing the board to see if it's conductive.
On the lowest range, touch the meter leads together to make sure the meter will go to 0 ohms.
Not trying to thread jack but i just have a quick question relating to this exact same amplifier.I have this same amp and when I got it there was already IRFZ44Ns in the power supply section.Did Alpine make a change or was the amp perhaps previously repaired?
okey, Perry, i dont have a auto-ranging.
after setting the settings to the lowest range and measured the output transistors, the results where OL on all off them, measuring the 2. and 3. leg. this is good news, right?
i switched over to the highest range and checked the burned areas, all of them i measured resulted in OL. soo, i guess thats good too.
how many watts should the resistors before the transistors handle? 0,25w?
what kind of resistor is the one who handle 1w, with a resistance of 10ohm? R055 on the board.
the list of components i found at this time:
4pcs IRFZ44NPBF transistor
50pcs 0.0068uF 50vdc cap
10pcs CFR16 carbon film resistor,100R 0.25W - 0,16,- pr (or should it be metalfilm?)
10pcs CFR100 carbon film resistor,10R 1W
minimum order quanty is BS :o
i am also setting up a thermal controlled relay circuit so the amplifier will turn off before anything happends. don`t want to waste this amplifier. costs me about 30usd only.
Should i check anything else before beginning to order this components?
i am also having a hard time finding the 111J/110ohm resistors, one of them looks like its abit burned, but i measured it to about 109,8ohm so this is ok i think.
I believe that alpine began using IRFZ44s after the NDP605s went obsolete.
It appears that the outputs are OK and that the burned area is not conductive.
The gate resistors are probably 1/8 watt. You can use 1/4 watt but you'll have to install them standing. Both carbon film and metal film will work fine.
The 1 watt resistors were metal oxide film originally.
The amplifier has thermal protection.
The 110 ohm resistor reading 109.8 ohms is well within tolerance.
With power applied to the amp (including remote), measure the DC voltage on pins 9 and 10 of the TL494 for the power supply that failed. It should read ~1/2 of the voltage on pin 11.
When you get the new parts installed, clamp all transistor tightly to the sink and use a 10 amp inline fuse between the power supply and the B+ terminal of the amp. This will help prevent damage to the new parts if there is another problem.
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