yamaha dsp a1000 swiching on and off

[homertooties]

Hello everyone well its been a while hope your all good....

I am in process of trying to fix a yamaha dsp a1000,bought it faulty
for ten pounds gonna try and fix it or strip for parts....

Here is the problem ...you switch amp on 2 seconds later switches off again,desoldered all output stages ,desoldered -and + rails supplying power amps no difference,there are five amplifiers ...front,back,centre
are the high pow ,and the rear channels are lower powered ones

Checked output transistors predrivers changed the 22000uf psu caps
no difference doubt its the transformer as it is huge,seems to me it is a psu problem...

Does anyone have a service manual they could mail me or any advice would be fantastic...also checked the impedance switch and cleaned it....

[CSlee]

Old thread revival.

I just had one of these come into the workshop, not overly confident with SS amps of this size, especially with all the DSP getting in the way - but it is showing the same problem you have here. Did you get anywhere with it?

Amp turns on for a half a second, then switches off. Few seconds later the relay at the mains inlet switches back.

In that second the transistors are seeing voltage from the power supply, they don;t seem shorted.

Does any one have any tips? I may just tell the guy to sell it for parts or send it to someone that knows more. But i'm up for a bit of fault finding.

Cheers

Charlie

[tauro0221]

Hi,
Here it is a link for the schematic.
http://www.sportsbil.com/yamaha/DSP-A1000.pdf

[CSlee]

Thanks, I found a schematic but was hoping the might be a tell tale answer to such a problem. Seems to be the same issue the OP had.

Just looking over the schematic now, there is so much DSP in this thing!

[tauro0221]

Hi,
I think there it is a micro that check the voltages to be within specs. and if not it will shutdown the amplifier. That it is a complicated amplifier to troubleshoot. The first thing to do it is check the power supplies voltages to see if they are OKAY.

[CSlee]

Certainly is a complicated amp. On power up the transistors see about 50v before the amp powers down again, so it seems to be working. I noticed in this thread Faulty Yamaha DSP-A2070 that there is a cap in question that may be faulty. It will be interesting to see how that pans out.

If i had the time it would be interesting to troubleshoot in detail, but I am not confident with the DSP and ICs in the amp to start pulling things apart.

Thanks for your help

Charlie