Digitech - PDS 1002 Delay  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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CheapPedalCollector
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Post by CheapPedalCollector »

I just got a PDS-1002 in the box, this thread is wicked helpful, thank you all.

I have delay but it's very distorted, so I bet it's an opamp, the ne570 or busted fet. Maybe it's also 4007 since the hold doesn't work but could be the footswitch I guess. Will post results to help anyone else later.

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Post by CheapPedalCollector »

Been ages since I worked on DOD/Digitech stuff in any capacity, I remember why I hate them now. Awful mechanical designs, the way they put the molex connectors is beyond stupid and it bends the input pot. Wasted 10 hours on it, can't find anything wrong. I suspect one of the FETS is bad but I don't have or can find any P100 or P200 ones. Just gonna sell it for parts.

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Post by CheapPedalCollector »

Dug this thing out again as I didn't want to be defeated.

In my unit I was having the same issue with the mute circuit being always engaged. C35, C36 and C37 were all bad (between 2.7 and 3.3uf). Q8 was also bad. Replaced and the unit is working as it should again.

Including pic with their location on the circuit board.
pds1002.jpg
Subs for PN100A and PN200A are 2N4124 and 2N4125 if needed.

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zwkelly
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Post by zwkelly »

I'd like to revisit this thread - it has been so useful.

Same story - PDS1002, won't do all the things, but kept it powered yesterday and now it works. I can use the first mode - 125ms - and all is good. However, I can't use 500ms or 2s. Any advice on getting all the modes to work? Everything else is there at this point.

I have two of these, which has been useful for comparison. One works just fine, and now I'd like to get this one back up to par.

Thanks,
Zach

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Post by CheapPedalCollector »

The connectors get dirty too check those and make sure they also have enough tension. Clean the switch. If it's not that maybe you have some bad ram or the selector has issues. Those caps I highlighted have something to do with all the delay modes and the middle one is often inserted backwards on the board.

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RodrigoMartins
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Post by RodrigoMartins »

Hi. I need some help too, with my Unit, so, lets ask in this helpful thread.

Mine is a PDS 1002, and the wet signal that is coming is just like a loud out of tuning old radio, with some clock noise. When i turn down the mix pot, the dry signal is ok

Changed the memory 41256, some small opAMP and capacitors - with no luck.

Any help would be appreciate

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dperry
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Post by dperry »

CheapPedalCollector wrote: 31 Aug 2021, 16:21 Dug this thing out again as I didn't want to be defeated.

In my unit I was having the same issue with the mute circuit being always engaged. C35, C36 and C37 were all bad (between 2.7 and 3.3uf). Q8 was also bad. Replaced and the unit is working as it should again.

Including pic with their location on the circuit board.
pds1002.jpg

Subs for PN100A and PN200A are 2N4124 and 2N4125 if needed.
I have a recently acquired PDS1002 with what sounds like similar issues to yours (500ms works, but 125ms and 2s are bad) If the internals are the same, I assume C35, C36 and C37 are the black or blue electrolytic caps as inside of mine are all yellow coloured. Also, is Q8 the transistor at the bottom of the board next to the trimmer?

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dperry
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my favorite amplifier: Fender Super 60 or Teisco Checkmate
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Location: London

Post by dperry »

dperry wrote: 18 Jan 2024, 09:59
CheapPedalCollector wrote: 31 Aug 2021, 16:21 Dug this thing out again as I didn't want to be defeated.

In my unit I was having the same issue with the mute circuit being always engaged. C35, C36 and C37 were all bad (between 2.7 and 3.3uf). Q8 was also bad. Replaced and the unit is working as it should again.

Including pic with their location on the circuit board.
pds1002.jpg

Subs for PN100A and PN200A are 2N4124 and 2N4125 if needed.
I have a recently acquired PDS1002 with what sounds like similar issues to yours (500ms works, but 125ms and 2s are bad) If the internals are the same, I assume C35, C36 and C37 are the black or blue electrolytic caps as inside of mine are all yellow coloured. Also, is Q8 the transistor at the bottom of the board next to the trimmer?
Ok - I've "fixed" it I left it switched on (effect engaged) in every mode for a few hours until the infinite repeat function LED worked in every mode. Now the pedal seems to work fine.

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