Bad progress on Sure-Q.E.D.

When bad things happen, they don't happen alone, they do a 7-hit combo.

Finally managed to solder the soft-start and remove the resistors to ground. First thing that happened when I hooked it up to my main system was a huge-ass-loud high-pitched buzzing. Apparently some bad connection or something, or maybe a short to ground. Got it fixed temporarily by connecting the banana connectors straight to the amp board.

Next, there was some hissing from the amp, but only with the signal wire connected to the amp PCB. EMI from the PSU.

So I used aluminum foil to wrap around the wires and capacitors as shield - why bother spending much money on shielded stuff when something cheap works better. It seems that class-D amps require triple-shielded input wires, I have aluminum foil wrapped around the wires a few times, this should count as 1.5 layer. And I have two of them - one for each individual channel (or each channel + ground where they split), and one for the whole bundle.


There is no potato underneath.

This sure helped a lot, and I haven't tied the drain wire yet, but there is still a tiny bit of hissing left, perhaps the drain wire plus some additional shielding will help. There is also some high-pitched noise when the socket is not connected to a source that is switched on, perhaps some grounding issues. I'll try grounding the signal ground to see what happens.

However, while moving the length-limited wires, or more correctly called bulkhead now, one of the disturbed solder joints on the volume pot came off. So the amp is not working again.

And to make things worse, my iron was spoilt for some reason, it just does not heat up.

It was meant for me to change it since long ago anyway. I've had many bad solders because of it. I think it has a short-circuit too somewhere, as I can feel current flowing through my hand if I hold the solder.

What was supposed to be a soldering iron

A new one, preferably with ceramic tip for long-life, and a trip to DX for the accessories. SLT still sells the good irons and third hands cheaper.

And to top it off, I couldn't check the connectivity of the connectors, or where the iron was broken, because my multimeter was out of battery because I accidentally forgot to switch it off after the previous measurement, and the neighborhood hardware store that has its battery was closed for CNY.

And I couldn't go home to complete this this weekend because I have Maths, Physics and Material Science CA next Monday to Tuesday.