JVC receiver RX-5032VSL "OVERLOAD"

[Chungalin]

5.1 receiver. Powers on normally and after a few seconds "OVERLOAD" blinks on display and doesn’t activate speaker output relays.

No power transistors shorted (2SB1560, 2SD2390 x5), output of each channel at 0V, no DC... Looks like a defective Protection detection.

PROTECTOR_IN line is at about -0,1V instead of expected 5,1V in normal state, but inputs of detector circuit are normal (-B from all channels on PROTECTOR lines and 0V from outputs). Q1302 (KTC3200) presents -B voltage on each leg, this is not normal according to schematics. Changed and fixed it!

It’s very important to screw ground tab EP301 when making tests with AMP board, because otherwise +B -B get ungrounded and this can damage amplifier.

I’ve found other issues with this same transistor in Denon receivers. I fixed a AVR-1311 and AVR-1910 with defective KTC3200 in amp section. I think it’s not a coincidence.

[Longbow]

Re: JVC receiver RX-5032VSL "OVERLOAD"

5.1 receiver. Powers on normally and after a Q1302 (KTC3200) presents -B voltage on each leg, this is not normal according to schematics. Changed and fixed it!

So are you saying that you found a shorted transistor, and that an intermittent pcb ground caused the problem?

[Chungalin]

Re: JVC receiver RX-5032VSL "OVERLOAD"

No. It wasn’t that easy. That KTC3200 wasn’t shorted under the basic diode tests (B-E, B-C, and reverse), but it didn’t behave correctly under normal load operation. It wasn’t an intermitent condition, it was permanent.

PCB ground didn’t cause any problem. I said that it’s important to screw at least that gound contact when making tests to the amp board. If you need to change some component on amp board, you don’t need to fasten all PCB screws each time you test it, but EP301 is absolutely required. One time I forgot to screw it and then it made a terrible UUUUUU sound. Luckily I unplugged it immediately and nothing bad happened.

[bobale]

Re: JVC receiver RX-5032VSL "OVERLOAD"

Just to chime in, I was having the same OVERLOAD problem with RX-5032VSL. I expected one of the channels to be blown or something along those lines, but even with all the amp board disconnected I was getting overload message.

To cut the long story short, always have good look around the protection circuit. In my case the problem was bad switching diode D1307. It was conducting in oppsite direction as well, and that was triggering the protection circuit.

[Chungalin]

Re: JVC receiver RX-5032VSL "OVERLOAD"

Thanks for the feedback. D1307 is a 1SS133. These yellow ones are common fails in protector circuits.