Sony V333ES Amp with a rapid clicking relay and no power

[fbcds82]

Hello, i'm a newbie to this forum. Been searching google for an amp problem and came across this site. Hopefully somebody knows what could be causing this issue..

I had received a Sony V333ES Receiver from a friend who was going to toss it as he said it didn't have power. Upon looking at it, the fuse on the stand-by board was blown. He told me he replaced a bad fuse and it blew again, then he went out and bought a new receiver.. He had installed a 5amp fuse where a 10amp should be. I went to radio shack, bought the proper fuse and now when I plug in the amp the relay on the stand by board is rapidly clicking like a machine gun and won't stop till I unplug it.

On this standby board, there is 3 plugs on it. One going to the main transformer, one is the ac line and one is a smaller cable that goes over to the complete opposite side of the unit to a very long board and that board has a ribbon cable that goes to the front board of the unit. When I unplug the main transformer it still clicks away, but when I disconnect that small cable, the clicking ceases and nothing happens.

Trying to route the problem, unplugging and replugging cables as I go to pinpoint the issue, the only 2 things I came up with is when the front pcb board is disconnected the clicking stops, and when that is plugged in to what appears to be some sort of digital processor type of a board, when I disconnect this from the stand by board, the clicking also stops.

So I guess my question is, what would cause a relay to rapidly click like a machine gun? This is the same relay that you hear when you first power on the amp. It's the only relay that I saw in this unit. Just wondering if anybody had an issue like this on any other amps and what any solutions would be??

Appreciate any insight. I just hate to junk an ES amp. Was trying to save it from the landfill. Thanks.

[Mooly]

Would have to see a circuit diagram to help...

Usually any fault like this is caused by shorted semiconductors somewhere... can't be specific because without seeing it it's a total unknown.

For example is the main power supply a linear or a switch mode type ? To see a circuit and all would become clear. The relay will be under control of the microprocessor. It could be a shorted output stage and that the unit is entering a protection mode...

[ostripper]

This amp is 7 channel , 7 pair of darlington sanken outputs driven by 2-3 IC's. One pair or more have shorted causing DC, which triggers the relay.
Most likely , if you could identify the blown outputs/channel and disable it (unsolder the outputs and remove them) the other 5-6 channels would work.
I had a Sony 5 channel , actually swapped 2 good outputs from the center channel to the right channel .... got 3 years out of it.

OS

[fbcds82]

Thanks for the fast replys. I will try to see which ones are shorted and report back with what I find. Appreciate it.

[fbcds82]

I found the problem. It was a bad ground wire that went from the digital pwb board to the video processing board. I ended up pulling all the connections off it and slowly started putting one by one back in, plugging the amp in as I went till I found the problem. I hit the ground wire with the solder iron and the amp powered right up. I also hit all the sanken ic's with the solder iron too for good measure. Thanks for the insight.

[Mooly]

That's excellent news... well done