Hi everyone, I've got my old solid state hitachi amp out to use, all speakers are hooked up and it all works, well, the radio does, as does an external output connected, as when I connect my phone to it using an RCA to mini jack lead it works fine on either phono aux or tape monitor depending on which RCA connection I've put the lead into,

but, as soon as I connect that same mini jack plug into either one of the PCs speaker outputs, (which is the whole reason that I want the amp for in the first place) the second i turn the amp on it trips the breaker in the fuse box, which takes all the electricity out.

I have tried a replacement lead and have tested on all three amp inputs as mentioned above, and with 2 different computers but with no joy.

I was under the impression that the usual speaker output on the back of a PC can simply go to any amp and be perfectly fine, as that's what I've done in the past, yet this amp is having none of it.

Any ideas anyone?

Thanks in advance

Outputs on the PC ? Description please.

System, motherboard outputs, soundcard, etc ? As above.

No way can a computer, ( Unless it's seriously munted ) output enough power to trip a toddler, let alone a home powerbox, on the audio ports.

Do'z a standard pc speaker system work on these outputs ?

Do the Amp inputs work with other inputs ? ( I know you said they did but ?????? )

Do'z the cable your using work on anything else ?

This is the same system that I use on 2 pc's, and have installed on a number of client's systems and I've never come across anything slightly like this.

Is your audio cable shorting to a power cable ?, as that would be the only way I know to recreate this.

You have a serious electrical issue somewhere, probably involving a short to the mains.

Pc's only run 3,5,12, ish volts and even on amperage there is no way a pc should be able to create that problem.

No help I know but that is a truly bizarre issue that can really only be explained by a serious short somewhere, and unless you want to pay me to come over and troubleshoot it, more info is really required.

Yes a standard set of PC speakers, and also the built in monitor speakers work absolutely fine off the output of either machine, one is an HP 09e8h motherboard which is obviously an intel on board sound setup, not sure which chipset it is but it's an intel and uses the ac97 driver, and the other PC has an Asus a8v-vm-SE board which is again an inbuilt sound card, and I'm using the green speaker output of each machine.

I have used this amp with the former PC in the past, the only difference being that I had everything, PC, TV, tape deck, CD player and 2x turntables all on their own channel of my 6 channel mixer, so all i can think is that having that piece of hardware in the chain did something that prevented this behaviour.

There are no shorts of any kind that I can see and the leads in question are also tried and tested, as it's the same one that I have tested all the available amp inputs with using my phones output.

"old solid state"

It's probably developed a fault which has made it unsafe to use. If you have the schematics you could try fault finding, if not finding a competent service engineer is a bit tricky in this modern throw-away world.

it seems likely the audio input on the amplifier is actually live to some degree, and connecting that to the earthed audio output on the computer will trip the safety devices on your supply. The mobile phone won't be earthed which is why it doesn't happen there.

Do not continue to use it until you find out what is wrong!

Yes it is pretty old, it's a hitachi sr 1100 which is circa mid 70s, I'll shoot over to my former workplace and borrow the PAT tester and bench, and see what it comes up with, thanks