DOD 680 Help

Discussion in 'Effects, Pedals, Strings & Things' started by MrBoZiffer, Feb 20, 2009.

  1. MrBoZiffer

    MrBoZiffer Senior Member

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    I just got a DOD 680 from a forum member and it's not working. He may very well be able to help, but I just emailed him. I don't want to wait around so maybe some of ya'll can help.

    First thing I did was plug in the power cord and flip the power switch to make sure it worked. The switch lit up and I thought everything was cool. So I turn it off while I get it situated on my pedalboard. I've got it all plugged in and ready to go. I flip the power switch... nothing. It doesn't light up at all and of course no signal goes through. It has yet to come back on.

    The switch looks to be hooked up properly (based on this pic http://files.muziq.be/pics/dod_680_002.jpg), but I'm not certain. There's a red, blue/black, and black wire going to the power switch. The red is coming from the transformer, as well as the blue, and both the blacks are from the power cord. Does anybody know for sure where these go? Any other ideas why it won't turn on? Some pics would help too.
     
  2. Dandy13

    Dandy13 Member

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    990
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    Oct 20, 2007
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    Cleveland
    I hope you get it working. Such a great delay- one of my faves, wish I still had one. It's getting harder and harder to find one that actually works
     
  3. MrBoZiffer

    MrBoZiffer Senior Member

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    Thanks. I'm assuming you have one. When you turn on the power switch, does it stick in the ON position... Like the switch on a surge protector? This one doesn't want to stick. It just goes back to the off position. It felt like a normal switch the first time I used it, but now that it's acting weird, it's giving the impression that the switch is faulty. I've heard that sometimes these have problems with chips, but I think this is a switch problem.
     
  4. Dandy13

    Dandy13 Member

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    990
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    could be a switch problem. it was my first delay pedal so my memory is a bit hazy other than how great it sounded, pretty damn dark, and great oscillation. closest i've gotten since is a dm2. sorry i can't be more helpful.
     
  5. MrBoZiffer

    MrBoZiffer Senior Member

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    That's ok. I actually got it to work... kind of. I had to take the switch apart. I took the red rocker off and simply turned it on by using the tip of a screwdriver to adjust the pole contact. The delay sounds wonderful... just like I thought it would, dark and warm. However I'm a little surprised by how short it is... is that normal? I mean it's maybe half the time of my DM-3... I thought it would be a little longer delay than that. Does that sound right?
     
  6. Dandy13

    Dandy13 Member

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    990
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    The delay should be short but not THAT short. Should be around 300 ms which, i believe, is the same as the dm3 (i've only ownd the dm2) Sounds like someone may have adjusted the trims. Can you hear any clock noise at max delay time? Does it self oscillate?
     
  7. MrBoZiffer

    MrBoZiffer Senior Member

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    That's what I was thinking too. First of all the delay is backwards to my DM-3... it goes longest to shortest. No clock noise. Once it gets past about 2 oclock on the delay time, it's too short to notice the delay. It'll self oscillate with the repats (which sounds really nice btw), but I'm not getting much more than a slapback echo. The trim pot is not a clock, it must be bias. I wonder how you adjust the clock? Unless it's fixed???
     
  8. Dandy13

    Dandy13 Member

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    990
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    yeah my dm2 goes longest to shortest as well, i think that's normal. i never opened up my pedals back in the day so i have no idea what's inside as far as trims.
    if you're not getting any clock noise, and it is oscillating properly, chances are the chip is good. i'm just going by experience tho, I have no technical knowledge.
    I remember cranking the repeats and getting a sweet sounding reverby wash going, that's how i used it . Probably not much more than slap back but you should def be able to hear some separation between the note and the repeat.
     
  9. MrBoZiffer

    MrBoZiffer Senior Member

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    I've got a schematic, although I'm not an expert at reading them, but it looks like two of the chips don't match up. That might be my problem. Both look a little out of place... their font is different from the others. I'll post some pics of them in a minute. Maybe someone with some more internal knowledge of it will notice. Thanks for your help Dandy! :AOK
     
  10. MrBoZiffer

    MrBoZiffer Senior Member

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    The Reticon, the 4558s, and the CD4013 all match my schematic. The LF351N and the NE571N do not match. Can anyone verify this so that I know I'm reading the schematic correctly?

    [​IMG]
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  11. starfish

    starfish Member

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    IIRC, there were a couple versions of the 680. The chips are likely correct and your pedal may not match the particular version schematic. That one chip appears to date to 33rd week of 1981 (8133).

    I had one of these a long while back. I've also owned the 670 and 690. The 680 is a great analog delay. A little dark - typical of the Reticon BBD, but still has analog warmth and with superb oscillation.

    Did the switch work after you realigned the poles? It might have been a jam.
     
  12. jfromel

    jfromel Member

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    Check the value across the sweep of the delay time pot?
     
  13. MrBoZiffer

    MrBoZiffer Senior Member

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    I have schematics for two versions one with 4558s and one with 4136s. I considered the fact that there could be mixing of chips, but neither schematic has these on there. That really doesn't mean anything though. Besides, both the chips in question have 81 on them so I think you're right... they are likely correct.

    Yes the power switch is working, I just have to use a screwdriver to flip it as I took the rocker off. I'll have to track down a new switch. If anybody knows where to get one, please let me know. It could take me hours going through Mouser to figure it out, so any help would be nice.
     
  14. MrBoZiffer

    MrBoZiffer Senior Member

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    How do I do that? Use my multimeter on the lugs while I adjust the pot? What should I be looking for?
     
  15. MrBoZiffer

    MrBoZiffer Senior Member

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    457
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    Fixed it! Never under estimate the power of compressed air. I hosed down all the components best I could and it sounds much better. Maybe something was blocking a pot, who knows. haha

    I even fixed the rocker of the power switch... part it had broken off so I glued it back together and now it works like charm... but no telling how long it'll last so I'll have be on the lookout for a replacement. Anyway, this thing works great now so thanks for everyone's help and input.

    Btw, if anybody knows where I can get a replacement power switch, preferrably one that matches, please let me know. Thanks!!
     
    Last edited: Feb 21, 2009

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