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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maxoche
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Post by maxoche »

i was looking this schematics for a long time !!

i have a pds 8000 and a 1000. they are both wonderful tools.

thanks a lot

max

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gtr-fxr
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Post by gtr-fxr »

did you ever figure out what was wrong. i am having the same problem

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sonic_tooth
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Post by sonic_tooth »

Alex Frias wrote:I tried to replace every soqueted IC in this thing and nothing changed in a positive way...so...
Maybe next weekend a friend will help me with his oscilloscope. Let´s see, if I find somthing I will share it, be sure!

I have 2 PDS1002s one is in working order the other has the same problem as some of the other non working units in this thread. I tried swapping all of the ICs in my units and it did not fix the issue either. It has to be something that is on board that is not socketed.

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Post by pinkjimiphoton »

hey guys, now i got one of these dead doorstops too...i started trying to trace it out without the schematic, and have B+ to the anode of d1, but that's it...no led, no dry signal,
making me think it's a ground issue (or that 4001 took a hit with the wrong power supply)...this schematic will be wicked helpful, thanks ron and everyone.

but i do wanna ask...could anyone post a couple gutshots of the off board wiring? i'm wondering if it's got something wrong.

thanks!
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sonicblue99
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Post by sonicblue99 »

Same boat here. Anyone have any luck? I have a PDS2000 that has no delay. Symptoms; leds light up, bypass signal is there, just no wet. I've tried swapping out the ICs with the spares I have with no luck (everything but the ram chip and two others were replaced. I used the chips from my working PDS8000 which was identical aside from the Ram and two other chips; counters I believe.) I'm going to order some replacement chips, but thought we could all troubleshoot this. Also, I do have schem for the PDS2000 but not the PDS8000 so I'm not sure how close the two are.

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Post by Dirk_Hendrik »

Conclusion scanning sthis thread: The problem is not in the chips.

next step: get a scope and start tracing. Clocks available? Activity on adress lines? Activity on Datalines? R/W signals available? Etc, etc.
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Post by Beedoola »

I just got a PDS 1002 today that needs some work. The delay works with the range switch in the 500MS range. There is no delay in the other two ranges however. The switch seems to be working alright.

Also. Are the output and input levels supposed to go beyond unity gain? With both pots maxed, the bypass vs. effect on gain is the same...

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Post by Dirk_Hendrik »

First suggestion that crosses my mind for all described cases is that the signal is muted when the range switch is changed. It seems this mute circuit seems to hang, causing continuous mute.
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Post by Beedoola »

where is the mute circuit on the schematic?

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Post by Dirk_Hendrik »

Q8
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Post by Fender3D »

and Q11-NE570 pin 1

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Phildog
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Post by Phildog »

Hello all. This is my first post.

I've used the search bar, but was unable to find anything on my specific issue.

As noted above, I have this delay pedal. But it will NOT power on. I don't have the adapter, nor one that is compatible with it. Today, I tried several batteries, and none of them would bring the unit to power. I've since taken it apart, hoping to find a broken or loose solder joint, but nil. Everything looks fine, and appears not to have been touched (re-soldered). So for poops and giggles, I re-flowed the solder joints on the jacks, and power connector. I also re-flowed the solder on the footswitches. Then, I used my CRC Electronics Cleaner and cleaned the jacks, switches, and the connectors to the board. I left it sit for 20 minutes or so...just to be sure that everything was totally dry. I was really confident that it was just dirty, but when I re-installed three different batteries, NOTHING!!!! Is there something that I'm overlooking? Are these batteries NOT producing enough milliamps to operate the pedal? I see on the factory sticker that it calls for a 10v adapter, so I plugged it into my SKB Stage 5. I dialed in about 10v and still no glow.

Any insight or direction would be greatly appreciated.

Thanks

Phil

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box
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Post by box »

Hi,
please check this link:
https://www.freestompboxes.org/viewtopic.php?f=1&t=3479
Recheck your power supply socket and all connections to the IN and OUT socket(ground).
Good luck,
box

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Phildog
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Post by Phildog »

Thank you. That should help out a lot.

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Post by DJGlukBH »

Same thing with my PDS1002. Actually got the unit non-working from ebay. Replaced 4096 (was drawing current), but got wet wit hdry signal only. Found de;ay signal on pin2 of NE571 - but no from pin7. Replaced NE571 - no use. Then the mute curcuit is bad. Removed Q11 for a while - got good wet signal with repeats. Checked Q11 - good. Then I need to go and check U7 flip-flop work... Hope that it's bad and after replacement everything will be good :)

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DJGlukBH
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Post by DJGlukBH »

DJGlukBH wrote:Same thing with my PDS1002. Actually got the unit non-working from ebay. Replaced 4096 (was drawing current), but got wet wit hdry signal only. Found de;ay signal on pin2 of NE571 - but no from pin7. Replaced NE571 - no use. Then the mute curcuit is bad. Removed Q11 for a while - got good wet signal with repeats. Checked Q11 - good. Then I need to go and check U7 flip-flop work... Hope that it's bad and after replacement everything will be good :)
Yup, it was U7 causing the circuit to be forever mute. Replaced it and the delay is healthy now!

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Post by DJGlukBH »

Got pds1002 for repair.

Current draw is 180mA so I've started with IC removal... 4007 appeared to be dead. Replaced, got 40mA draw which is OK. But only dry signal, effect switch (right button) is working, hold is not (blinks, then turns back off). Will continue research on this and will keep this thread posted...

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Post by DJGlukBH »

DJGlukBH wrote:Got pds1002 for repair.

Current draw is 180mA so I've started with IC removal... 4007 appeared to be dead. Replaced, got 40mA draw which is OK. But only dry signal, effect switch (right button) is working, hold is not (blinks, then turns back off). Will continue research on this and will keep this thread posted...
NE570 has the delayed signal... But nothing on the output opamp, looks like that I have forever mute issue again. Will check Q11 and the second 4007 tomorrow...

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ramonovski
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Post by ramonovski »

DJGlukBH wrote:Same thing with my PDS1002. Actually got the unit non-working from ebay. Replaced 4096 (was drawing current), but got wet wit hdry signal only. Found de;ay signal on pin2 of NE571 - but no from pin7. Replaced NE571 - no use. Then the mute curcuit is bad. Removed Q11 for a while - got good wet signal with repeats. Checked Q11 - good. Then I need to go and check U7 flip-flop work... Hope that it's bad and after replacement everything will be good :)

Yup, it was U7 causing the circuit to be forever mute. Replaced it and the delay is healthy now!
I just got a PDS 1002 with the same issue as many of you, no wet signal.

I've been trying to find that U7 but I can't find the exact model of the IC in my PDS which is MC14007U, I found this on ebay: https://www.ebay.com/itm/NOS-MOTO-MC140 ... 43c29aab04

Do you guys think this will work as intended? Of course I'm not expecting this will "fix" the pedal, but I could give it a shot.

BTW, is there any place where you guys get your ICs and everything else for your stomboxes?

Thanks so much in advance.

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Post by Fender3D »

Remove Q11, whether it works is either Q11 or 4007...
usually those f...ing 4007s break...
Any 4007 will do the job, but @ ~6 bucks + shipping I'd rather go SmallBear or similar safer places...

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