[Guest]

So's mine... What's going on?

[Guest]

[absorbentgnome]

1) Resolder all the output transistors solder joints and any other intermediate transistor stages that are attached to the heatsink. Also check joints on any large components (you may see some white resistors nearby). Poor joints can cause current spikes that may trip the amplifier.

2) Have the transistors got exposed metal tabs? Check the thermo-conductive pads behind them.

3) Check circuit board mounting points for loose screws or possible shorts. Re-seat the PCB.

4) Check for silly bits of wire around the speaker connections and the connectors location on the back panel. It may be intermittently shorting to ground, depending on the connector type or old bits of wire inside them.

5) If you can cause the problem by poking the PCB or wobbling the heatsink, then you may find the problem. Don't poke any parts connected to the mains, though. Heh.

[svekro]

Hi,
There could be some problems with your output transistors. It is the overcurrent protection who switches off the amp if there is faulty transistors.

[alexeix]

Hi,

My Yamaha DSP-AX620 AV amplifier switches itself off immediately after I switch it on. This is an intermittent problem, in that it will happen constantly for a while, then will 'fix' itself for a time (e.g. anywhere from a few days to a few weeks), before happening again.
The display comes on and the machine clicks on, but then it clicks off again straight away.

It started happening several months ago, out of the blue. The unit isn't over-used and doesn't get moved. However, the TV stand in which it sits, does get moved once every couple of weeks or so, but purely to gain access to cables at the rear.

In order to try and identify the cause of the problem, I disconnected all the speakers from the amplifier, one at a time (including the subwoofer), but it made no difference. I also tried disconnecting all of them together, so I think I can rule out shorts on any of the speakers, as the problem still happened.

I THINK the problem is the power cable, because at various times, I have managed to get the amplifier working by shaking the cable, or manipulating it into a particular position, however, at other times, this technique hasn't worked.

Has anyone come across this problem before and know what's wrong?

I will check the wiring connections at the amplifier and plug, but failing that, I will replace the power cable. What sort of cable would I need?
I'm based in the UK.

Any other suggestions???

Thanks in advance.