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old block Phase 90 broke - HELP!

Discussion in 'Effects, Pedals, Strings & Things' started by sl1960a, Feb 22, 2006.

  1. sl1960a

    sl1960a Supporting Member

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    I just recently dug up my old MXR Phase 90 - I opened it up, stuck a battery in it, and tested it - it worked. After playing with it for a while I checked out the board - the foam wrapped around the board has pretty much rotted all the way - it was stuck to the board on both sides - when I was rubbing off the foam rot, the purple wire (from the output) came off from the board and I have no idea where it is supposed to go. I've looked at some schematics to try to figure it out, but between the foam rot and resistors that are too disscolored to see the values, I can't seem to figure it out.

    Would somebody on the board be able to help me? I am not too knowledgeable and could use some assistance.

    The board is rectangular with the two top corners angled. Looking at the board from the bottom (not the component side) from left to right, there is a gray wire going to the middle lug on the pot, below an to the right an orange wire going to first lug, in the middle a red wire to the battery, nexta black wire going to the input pot, and on the far right a yellow wire going to the input jack to the switch. Any help would be appreciated.


    Thanks - Mark
     
  2. gururyan

    gururyan Member

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    [​IMG]

    Well, there is my '79 guts.
     
  3. sl1960a

    sl1960a Supporting Member

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    Thanks Ryan, but I didn't see the pic or a link. If you would please post it or email it to me I'd really appreciate it.
     
  4. gururyan

    gururyan Member

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  5. sl1960a

    sl1960a Supporting Member

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    Thanks again Ryan - The firewall here at work is stomping on pics. I'll have to wait until I get home. <sigh>
     
  6. scottywompas

    scottywompas Member

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    can you post a pic of the other side of the board?

    Scott
    :dude
     
  7. gururyan

    gururyan Member

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    If I had more time I would, with a house full of two kids and an adult with some nasty stomach virus...I am running around with vomit bags and refilling toilet paper. I had that pic on my computer from last time somebody asked me to take a pic. I'll see if I took one of the other side. I should have when I dismantled it completely to cover the box in leather.
     
  8. scottywompas

    scottywompas Member

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    I hear you brother. Take care of the family first. I'm sure this phaser thing will get worked out.

    :RoCkIn
     
  9. sl1960a

    sl1960a Supporting Member

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    Okay, I made it home and I can see your pictures. The problem now is my circuit is different. The shape of the board is the same, but my circuit is not the same as Ryan's pics. My phase 90 only has three IC chips down the middle and five transistors - three on one side and two on the other side. Also my trim pot is in the opposite side than Ryan's pic - it's up by the angled corners. Additionally, I'm was hoping to find out where the wire (mine is purple) from the output jack goes into the circuit on the the board from the bottom (not the component side). I do appreciate everybody's help considering the circumstances. I'll dink with it later tonight after band rehearsal, but if somebody does come up with a solution, I'd appreciate it very much.

    Thanks Again - Mark
     
  10. scottywompas

    scottywompas Member

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    I was looking at a schematic and it looks like the output comes off a .05uf cap. Is there a cap marked .05 .047 473 or anything like that on the board? THere should be an hole next to wherever this cap is or an hole with a trace going back to this cap.

    Scott
    :dude
     
  11. sl1960a

    sl1960a Supporting Member

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    Thanks Scott - I saw you post last night when I got home, but went to bed so I could get at least four hours of sleep. :(

    I just need some quality time to work on it (rehearsal with band two tonight). What I really need to do is get some better light and a magnifying glass to help these old eyes to check out the caps. I'll update later.

    Mark
     
  12. sl1960a

    sl1960a Supporting Member

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    FYI - Issue is resolved!!

    THANKS - Mark
     

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