Troubleshooting a TC Electronics Dark Matter

[Rutger]

Hi,

I hate this when it happens and I even more hate to send it back... the Dark Matter just arrived by mail and it is not working. If they can't do it properly themselves then I am happy to fix it myself... if it is not too complicated  I have build some stompboxes in the past and I know mu way around electronics a little, but just diy level kind of stuff. Before I open up the stompbox I would like to ask if you can help me guess what to look for...

So what happens when I kick on the stompbox: all the pots are noisy and scratchy... even when I touch the enclosure it makes noise... sometimes there is100% signal, sometimes 50% and sometimes nothing at all...
The noise sounds like AC leake somewhere. And it affects al the pots and the in/out. My guess is that there is a loose whire somewhere.

[jgenet99]

It's difficult to diagnose without looking more, but my first thought about touching the box and getting the noise is a grounding issue. It very well could be something making contact intermittently, which is why it's sometimes working and other times not. It might be a fairly simple thing to fix. It's possible that something from the signal is shorting (probably to the box) which can cause partial or total signal loss (volume knobs typically make the volume softer by partially dumping the signal to ground). You could take it apart and look over it for anything that seems amiss (I bet it doesn't even have a wire in it, as they mostly do it all on a printed circuit board these days!) but it could be some of the hardware that's bent into the frame. I'd be suspicious that it's terminals from the jacks, but again, I think they are plastic boxes soldered right on the board in those. It's certainly possible that it's losing a connection towards the end, maybe a bad soldering joint, and that can be more tricky on something like this. Definitely be sure to run it on battery and adapter if you can, just to rule out power, and try different cables input and output to rule that out. Touching the box sounds like shorting, but I've had issues where if the cable isn't making good contact, just a slight amount of pressure can cause it to come in and out. If you want to post pictures of the inside we could definitely take a look.

[Rob Strand]

It's easier to open it up and look for obvious problems.  All the stuff jgenet99 mentioned would be high on the list.

Assuming the box is plastic: From outside the box you could try connecting a wire from the ground of the input jack to the ground of the output jack.   If it comes back to life then that would be a broken ground wire/bad soldering.   If it doesn't fix it then maybe it's a broken signal wire/bad soldering.

I guess the problem is if you start dismantling things and desoldering stuff but the problem is beyond what you can fix then you might have trouble sending it back.    However, if you just send it back as dead on arrival they will just ship a new pedal out, end of story.

[Rutger]

Thanks!

I indeed tried abattery and powersupply and used different cables to rule that out.

You are right that it is probably all soldered right on the pcb and that should make things a little harder. I will open it up and take some pictures, I guess it wouldn't harm to take a look

[jgenet99]

I have the Rusty Fuzz, similar case, it's metal (in reference to Rob)

[Rob Strand]

I have the Rusty Fuzz, similar case, it's metal (in reference to Rob)

Thanks, will need to open it to go further.

[Ice-9]

The Dark Matter is a very well made pedal and the grounding is well done using tags an the bottom. If you have just bought it I assume you mean brand new ? just sent it back, if second hand then open it up and you will see all the pots are mounted on there own little boards which connect to the main PCB using those horrible white single strand ribbon cables which are also hot glued. These are a weak point if the pedal has been opened up before so check out the connections here are good.