Help Troubleshooting Effect

[spartadrive_in]

Unit: DOD Digitech PDS 20/20 Multi Play

Problem: This thing will work great for a few moments then it will stop. In my view it seems that it "looses it's juice". It will either just stop (no sound) or it will slowly dwell out some notes until it gets quiet.
Even when I bypass the effect my clean signal will not get though.

I find that when I turn the unit off for a few minutes then turn it back on it WILL work. But just for a few minutes again then do the same problem.

Possible Solutions: Could it be a bad IC chip. There are a million back there. Luckily they are all in sockets so replacing one will be a snap (if that's the problem).

What could the problem be?
also: I havn't been able to find a schematic of this. anyone know?

Thanks.

[R.G.]

Unfortunately, there is no way to tell from only that information.

Something working and then running down is almost always a capacitor charging up or down and causing something to stop working, but without a schematic there is no way to say what and where. Even then you'd need to poke around inside, take voltage measurements, etc.

From here, it could be anything inside the box.

[Enzo]

You can order a schematic from DOD.

If nothing else look at the stuff that fails on ALL pedal effects.

Check for cracked solder on the power input jack where your adaptor plugs in.
Look for larger transistors or voltage regulators - three legged things - with cracked solder.

[spartadrive_in]

Schematic

The guys from DOD sent this to me.

Can anyone make sense from this? Any idea where to look for the problem?

[52 Bill]

This is not the entire schematic. Maybe it's all they have scanned for that pedal.

Like Enzo said, I'd start by checking the power supply. When it dies out, what happens with the power supply? If the supply voltages are ok, then start looking at the input and output audio circuits.

[spartadrive_in]

The lights are still on when the effect dies out. So I don't think it is the power supply?

Which are the input and output circuits?

I thought that something was missing in that schematic..

[spartadrive_in]

The lights are still on when the effect dies out. So I don't think it is the power supply?

Which are the input and output circuits?

I thought that something was missing in that schematic..

anyone?

[R.G.]

anyone?

I say this from empathy, not scorn. No one is replying because there is still not enough information to work with.

Someone with a lot of experience might be able to look at the insides, find and check power supplies and voltages, isolate the input/output circuits, trace the signal with an oscilloscope, find out where in the circuit path it dies, and figure it out.

No one can do that long distance with scalpel-like accuracy unless by sheer chance they've repaired the exact box with the exact problem recently enough to remember. I've lucked into doing that in the past. But that will be very rare. Enzo was trying to help, and gave you pretty much all he could, what he'd do if faced with it and no other information.

You're pretty firmly stuck with what I call easter-egging; guessing what might be a problem and swapping in parts. If you had the skills to run it down by measurement, experience and guesswork, you would already have done so, so you don't. About all it's possible to tell is that it's probably in the analog circuitry, not the digital stuff you have the schematic to; otherwise it would quit abruptly, not "run down".

We're not ignoring you, just can't help. Your options, other than raw luck, are to find a complete schematic, or take it to a skilled tech. It's very unlikely that you'll find someone on the net to tell you "Oh, just look at IC6, and if pin six is less than five volts, replace it."

[spartadrive_in]

Ok that sums it up for me. All help is welcome and that's about as helpful as anyone can get. I'll put this project on the back burner until I finish my electronics degree. Maybe then I will have a bit more know-how.
For the mean time. I have a lot of other projects to get to.
It's a mad house in here.

Thanks.

[Enzo]

I hope there was another page to that schematic, notice it says page 2 of 2 at the bottom right. Page 1 would have the input and output.

[spartadrive_in]

That's all they sent me but I will email them for that specifically.

[52 Bill]

I have to agree with R.G.

I for one, without looking it up, have absolutely no idea what a DOD PDS 20/20 is. That doesn't mean I haven't seen one or for that matter repaired one at one time. But when someone comes here and asks for help we all try our best to give basic advice based upon what we know, what we are told and to some extent what we imagine.

We all offer suggestions in hopes of getting you on the right track to finding the problem with the unit that you are trying to fix. Enzo, who has the patience of a Saint, will sometimes work with you to the point of detailed, how to, step-by-step troubleshooting, but only if you help him to help you.

Earlier, he suggested checking the power supply circuitry, did you do this? I asked what the power supply voltage did when the signal died out, did you check this? If you did any of this, let us know what the results were, as they are clues to the problem. The LEDs run on as little as 2-3 volts, the rest of the circuitry won't. If the voltage levels drop enough to kill the audio, but not shut off the LEDs, then that will lead the search in one direction. If the voltages are all ok, that will let us all know to look elsewhere.

If you are working on getting an E.E. degree, that's great, but what you can learn from listening to Enzo, will not be taught in any school.

[spartadrive_in]

Yes I understand what RG was telling me and I know what Enzo can teach me. He has helped me with my Symphonic record player and Peavey amp. I have learned alot about my toys and I have all of you to thnk for that. I will be checking the voltages tonight and will be hunting down the first page of that schematic (I emailed them again). Once I get those said voltages you asked for I will post them and maybe you can tell me if they sound right (if I don't have the schem by then).

Thanks again and believe me I am trying to help you help me but I only know so much. That's why I'm here. To learn.