JVC DR MV1B , DVD/VCR recorder

Mar 21, 2007 4 Replies

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N Cook 19 years ago

Not my usual area but willing to at least look at it despite inglorious reputation googling about. Owner was prepared to live with having to press on/off ten times from cold before it would settle into on/standby but now there is a sound problem. After 2 days powered up all audio functions gradually fail to white noise, ie play anything , record anything VCR or DVD or off-air. I've located 2 SIL, LA.... (closely surrounded in tiny lytics so cannot read) in area of board marked Audio In/Out , any suggestions. ? I get the impression it was on left and right so trace power line back to ps and selectively heat to induce problem.?

-- General electronic repairs, most things repaired, other than TVs and PCs

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Diverse Devices, Southampton, England

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b 19 years ago

You've probably done it I imagine, but change all the capacitors in the power supply secondary- these units tend to have abysmal ventilation and hence run hot. This gives rise to all kinds of weird problems such as the on-off trouble you mentioned. from there, after elimination you can delve into the trickier area of the audio circuit.

-B.

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N Cook 19 years ago

Its a dual tuner jobby so worth cobbling something together I've now read the numbers on this JVC DR MV1 audio SILs as LA7151 and downloaded the pdf, they are dual amps so maybe just a problem with one pack, but I'll trace back to the ps anyway. There is certainly browning of the pcb around the ps primary side driver? STR G6653? and browning to a lesser extent on the heatsink/pcb mounting areas, despite a reasonable size heatsink. The owner actually suggested putting in another or bigger fan. I will try and find what a Sharp PQ5EV3 is also in the ps

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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N Cook 19 years ago

cold

noise,

10.1V supply to the audio amps using an E-line 300mA pass tranny and a 10V smoother in the ps. Will uprate those and choke back the easy air supply on on the wrong side of the ps to force a greater fraction over the SMPS driver and add heatsinks to the 2 unsinked regulator devices. The fan seems powerful enough despite its small size, just the internal air run seems misdirected as though the ps was the wrong way round, the primary side is at a blocked off dead end almost and gaping holes into the rest of the chassis at the other end.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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N Cook 19 years ago

I RTFM and this m/c blinks for 50 seconds from initial plugging in by design.

Made the changes, will have to see in 2 days time whether repaired.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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