TS808 (I know, not a madbean sorry!) Power Supply hum (SOLVED)

[k.rock!]

Hello wise people at MadBean Land...I know this is not a madbean project, but the issue is hopefully something general that maybe one of you may have had this problem before?

The pedal works perfectly with a battery, but as soon as I plug in the DC power supply there's a very bad hum...Now, I checked the following things:

1) it's not the power supply. I changed to another pedal and I got no hum
2) it's not the power outlet. I kinda checked that indirectly on 1) but still, changed outlets, same hum
3) triple checked the wiring. Battery snap to middle tab, 9V send to board on little corner tab, Ground to L shaped opposite corner tab to board grounds.
4) checked the ground connections, soldering joints, bridges, the whole chimichanga
5) checked for any enclosure/surface shorting somewhere. Nope.

At this point I'm only suspecting two things. One, the ground tab on the DC jack may be defective? Or two, maybe I have a bad cap on the output buffer...

I'm open to any of your wise solutions

I don't have pics with me right now but if you guys need some I can post some probably on Monday (I'm out for the weekend )

Any help is greatly appreciated! Thanks!

-Kaleb

[jkokura]

Hey Kaleb, here's my thoughts. Hopefully we can get this working for you.

Hello wise people at MadBean Land...I know this is not a madbean project, but the issue is hopefully something general that maybe one of you may have had this problem before?

What project is it? Or is it an Ibanez unit? Knowing it's not a madbean project doesn't tell us what it is!

The pedal works perfectly with a battery, but as soon as I plug in the DC power supply there's a very bad hum...Now, I checked the following things:

So if it's fine on a battery, chances are it's the power supply. But see my notes below...

1) it's not the power supply. I changed to another pedal and I got no hum

Having it work in another pedal doesn't mean it's not the power supply. Checking another power supply would verify that it is or isn't the powersupply. I've had a similar problem, but changing the powersupply worked for me. I went from a Boss PSA unit to a Voodoo Labs PP2+ and the hum went away... The PP2+ is regulated AND filtered. It may be that the supply you're using isn't. That doesn't mean that a problem may not exist in the pedal also, because if the supply works fine in another pedal that indicates that there's at least SOME problem with the pedal.

2) it's not the power outlet. I kinda checked that indirectly on 1) but still, changed outlets, same hum

Changing outlets on the same circuit isn't enough. You need to check a different circuit in your power. If you've got two outlets on the same circuit with another noise creating device (like a fridge or a faulty light socket or something) you can have a problem pop up. Move to a different end of the house, or better yet, try it at a friends house.

3) triple checked the wiring. Battery snap to middle tab, 9V send to board on little corner tab, Ground to L shaped opposite corner tab to board grounds.

I'm not sure what you mean by which tabs things are going to. Different jacks have different pinouts. Double check and make sure the right lugs are attached to the right sources, don't assume it's right.

4) checked the ground connections, soldering joints, bridges, the whole chimichanga

And?

5) checked for any enclosure/surface shorting somewhere. Nope.

Good that you checked, but the best way to check is to remove the circuit from the enclosure and figure out if it's really the enclosure or the jack.

At this point I'm only suspecting two things. One, the ground tab on the DC jack may be defective? Or two, maybe I have a bad cap on the output buffer...

That may be a good diagnosis, but my money is still on a combo of the pedal and the power adaptor.

I'm open to any of your wise solutions

I don't have pics with me right now but if you guys need some I can post some probably on Monday (I'm out for the weekend )

Any help is greatly appreciated! Thanks!

-Kaleb

Hope that helps Kaleb. Really, without seeing it in person it's up to you to solve this. Hopefully we can point you to look for the right thing.

Jacob

[k.rock!]

Thanks for the quick response Jacob. The build is the GGG TS808 which I've made a few times now...When I said I checked all the soldering joints and such I meant I checked and did not find anything suspicious at all.

I see your point about the power supply. Unfortunately, believe it or not, I only have the one power supply since I tipically run mine in batteries for the most part (not the wisest thing I know, but that's besides the point haha)

The DC jack layout I'm talking about is your standard DC jack, nothing out of the ordinary...

I will buy a voodoo labs power supply tomorrow (since I need it anyways haha) and I will attempt that and let you guys know if that takes care of it. Otherwise I'll keeo checking everything else...I hope to have some pictures soon though. Thanks again!

[jkokura]

I've seen it.

By the way, only buy a new supply if you really want one. That's expensive if you're just buying it to test pedals. Nothing wrong with using batteries.

Jacob

[k.rock!]

Oh yeah I agree, but trust me Im not buying it just to test pedals...My pedal board keeps expandind lately so I'll definitely need something smarter to power them up...so dont worry about that hehe thanks!

[pandadandan]

Chiming in on the PS issue.
The main thing about the PP2 is that the outputs are also isolated, ie Each output has a transformer which acts as a barrier to prevent any kind of interference with the other pedals.

[k.rock!]

Guys thank you all so much for your help! I actually solved the problem today. Turns out that one of my transistors was reversed   felt like an idiot when I saw that...but I guess it happens

Fortunately i didn't fry it so the TS808 works wonderfully now. Again thank you for taking time and helping me out!

-Kaleb

[madbean]

Good to hear Kaleb. Thanks to everyone else who tried to help get this sorted out, too!