644 repair

Discussion in 'TASCAM DIY Repairs and Mods' started by keef, Mar 16, 2019.

  1. keef

    keef New Member

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    Hi all,

    This is my first post.

    I have been given a 644 Portastudio which seems to be in great condition and I would like to get it all working. The mixer section works fine as far as I can tell. Only problem is with the cassette drive. Fast forward and rewind work fine - I am assuming these are separate motors. The only issue is with the play and record which do not work. If I hold back the two small pins in the corner of the cassette slot the motor runs fine but if I insert a cassette the motor will attempt to run but will then stop. I am assuming this is a problem with the capstan belt. I have ordered a replacement belt but I cannot find a guide anywhere to undo the unit to replace the belt. Anyone have a few pointers as to how to open up this machine?

    Thanks

    keef
  2. Laszlo

    Laszlo New Member

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    From:
    Near Budapest, Hungary
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    34B, 122 MKIII, X-300
    Hey Keef,

    there is a lot of basic DIY stuff on Youtube , it is worth to look. There is no video on belt change of the 644, but the 688 which is the big brother of it, with the same transport.

    In case you are not familiar with this kind of activity, I would suggest to think everythig twice before you do it..These are fine little machines but they were quite complex and developed at the end of the cassette player era. Also mind that in case you damage the smallest piece, it would take a time travel to buy it in a regular shop :) It is not a bad idea to make photos before each phase too just to have it once get stuck in the reassemble phase. Good luck!
    Laszlo
  3. keef

    keef New Member

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    Hi Laszlo,

    Thanks for your reply and the video. It looks do-able to me if I can get the case open.
    It looks like the 688 opens in a separate section for the recording section. Looking at the 644
    I cannot see a join down the case at this point. Lots of screws underneath so maybe I will try this first. Good idea to take photographs.

    If I don't mange to repair the cassette I wonder if it is possible to attach a minidisc or computer to record and just use the 644 as a mixer?

    I have been reading the manual and it sounds like a very complicated machine.
    Let you know how I get on.

    Cheers,

    keef
  4. Laszlo

    Laszlo New Member

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    From:
    Near Budapest, Hungary
    Gear:
    34B, 122 MKIII, X-300
    Hi Keef,
    Since I dont have a 644 myself, I cant help too much in this. It would be vise to download the service manual from the net, and study the exploded views of the machine. That helps find out how to get inside. Dont start unscrew randomly screws on the buttom plate though, it might loosen something which is fixed to the bottom plate and once you unscrew it, it will be damn complicated undo it later.
    Since you are new to this Forum (at least you said it was your first post) I would recommend you to wait a bit for other forumers, since I know there is a lot of knowledgable persons who breath and eat daily this stuff, and some also have knowledge specific to the 644.
    On another note, you may use the machines mixer part solely, many do that. However, it would be a pity, since the really revolutionary thing in the Tascam home recording systems is the versatility and flexibility they built in, and these later machines offer really a lot.
    cheers,
    Laszlo
  5. keef

    keef New Member

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    Hi Laszlo,

    Thanks again for your reply. I have searched for the service manual but without any luck.
    I will keep trying. I have the operation manual. Reading this manual it does sound amazing what this machine can do.

    P.S I have also been given a Roland drum machine which works great.

    All best,

    keef
  6. keef

    keef New Member

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    Hello all,

    I have finally got a service manual and opened up the machine. I have rep[aced the belt. The old one was reduced to a small black sticky rubber deposit on the motor drive wheel. Obviously I cleaned this off before fitting the new belt. I have reassembled the machine.

    Unfortunately there seems to be no improvement. Fast forward and Rewind both work fine and so does the shuttle button. I still cannot get the tape to play. If I remove the tape and hold back the two feeler switches in the top corner then the motor turns and the transport engages. The moment I put a tape in it stops.

    If anyone has any ides as to what I could look at with this machine it would be appreciated.

    keef

    Tascam 644 with a new belt
  7. keef

    keef New Member

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    Hi,

    To answer my own question.
    The reason that play isn't working is that the capstan motor doesn't turn.
    Seems that the motor is a Mabuchi EG-530KD-2b and these seem to be extremely rare.
    May have to call it a day on this repair unless someone can suggest an alternative motor.

    keef
  8. keef

    keef New Member

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    Update: I have installed a new capstan motor which I found on eBay. Installation wasn't too difficult. Follow the instructions in the video above to replace the belt and then it is a matter of easing off the retaining plate, removing the motor, 3 screws, cutting off 4 wires and resoldering and then replacing everything carefully.

    All working fine.
    keef
  9. Artinspace

    Artinspace New Member

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    Hello and congratz on your 644. I recently got my own 644 ant try to solve same issue. Do you mind sharing service manual? Tried to open the machine but with no luck.