High VDC on speakeroutputs

[Xynter]

Hi,

I have recently completed my AMP-5 kit and now I have finished the speakers for the amplifier.
When I just had built it I had some problems with the DC output on the speakerterminals. But I fixed it then, but now I have the same problems and the VDC won't go below ~12,7. It's only one channel that has that problem the other one is at ~0,001mVDC.
I have followed and measured on almost every solderpoint and the voltage is completely off the charts if I compare to the other channel. By the potentiometers the working channel has ~0,001VDC over it and on the faulty one it's ~5VDC.

Could anyone help me with trying to solve this problem or should I give up an order a new kit?

The reason to why I said that I would order a new kit is that some solderpoints are wrecked and have separated from the PCB.

//Xynter

[V-bro]

Bummer...

Often this is related to the input wiring that bypasses the volume control chip position on the AMP5. Usually there is something shorted to ground...

You may have a defective potentiometer indeed. These are not too expensive to give a try...

[Xynter]

I haven't bypassed the DS1802 since Jan sent one to me, with all necessery components.
It sounds possible that something is by mistake shorted to GND. But I can't resolder the potentiometer since the PCB have been damaged just there... Yesterday I sacrificed a resitor and solderd one of it's pins between the "right" potentiometer and the one with the faulty voltage. It'didn't fix anything at all.

Maybe it would be best if I orderd a new kit, since the potentiometers are important and my PCB isn't fully functional.

[V-bro]

It always worked best for me to put such a project in the drawer for a while and get back to it later with more experience and a working specimen on the side...

[Xynter]

I'm gonna go on your suggestion, when I get home from work I'll order a new kit.
The only problem is that I'm looking on the AMP-10 kits. They have a layout that I think looks a bit better than the AMP-5 and if I would try to repair the AMP-5 I might run in to some trouble with some different voltages and that kind of stuff.

[V-bro]

Yes, go for the AMP10, sure! You will after some examination see the resemblences between the two and perhaps still figure out what's wrong with the AMP5...

Still this malfunction bothers me and I would love to see this solved! Have you also checked the modulator gain resistors? These are between some chip pins and 5V and AGND, here's also a big chance of shorts that can create DC offset... You would do well to check all connections with a DMM with no power on the board and discharged caps and have the schematic along side....

Can you also provide pics perhaps?

[Xynter]

V-bro I have pics in my other thread here, but they are only from a cellphone so the quality isn't the best.

I'll go for a AMP10 then and when I have the motivation I'll try to solve the problems with the AMP5.