Tascam 644 speed issues after replacing capstan motor

Discussion in 'TASCAM Analog Forum' started by clixor, May 28, 2021.

  1. clixor

    clixor New Member

    Joined:
    Jun 2020
    Messages:
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    Gear:
    Tascam 644
    Hi all,

    I had to replace the capstan motor this week, first i just wanted to oil the old capstan motor (excellent videos on youtube about that btw) but when opening up the motor i could see the unit was totally burned out (pcb was black and corrosive, and foam material was melted on the pcb).

    Luckily enough i was able to source an identical EG-530KD-2B used in an TASCAM 424 MKII.

    Now the color coded wiring was slightly different, i didn't solder the wires just yet just in case but stripped the wires and connect them that way.

    The upside is that the capstan is working and i can record again, recordings sounds magnificant (i dare to say even better than original digital source).

    Now i do have a few issues:
    1. High speed / low speed / var speed control etc functions are not working anymore
    2. Old tapes are playing on chipmunk levels of speed. A six minute recording takes about 40% of a 90 minute tape.

    Ofcourse i have to check the wires and solder them properly (i can post pics of the color wiring). But my first question is, is the speed of the capstan motor only determined by the speed pcb? Or can this be an issue with the new capstan motor?

    Second question is, is there a source somewhere for acquiring the recommended test tape(s)?

    thanks, Bas
  2. Laszlo

    Laszlo New Member

    Joined:
    Jan 2019
    Messages:
    64
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    From:
    Near Budapest, Hungary
    Gear:
    Tascam Revox Mechlabor
    Hello,

    You should know that these motors have internal speed control circuit, and if they break, you cant regulate speed correctly. The tuning pot of the motor is behind the rubber window on the bottom of the motor.
  3. Laszlo

    Laszlo New Member

    Joined:
    Jan 2019
    Messages:
    64
    Likes:
    15
    From:
    Near Budapest, Hungary
    Gear:
    Tascam Revox Mechlabor
  4. SkywaveTDR

    SkywaveTDR Well-Known Member

    Joined:
    Feb 2014
    Messages:
    817
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    From:
    Chicago area
    Gear:
    Teac, Tascam, Sony
    Putting in a motor not of the original type might be trouble and some motors were made for dual speed cassette decks that do not have pitch control. The original motor should have had marking such as +, -, A, B then the wires should be hooked up the same way on the new one. If the new motor has only two terminals then it is not for the deck you are putting it into. Some third party motors need modification to the speed control board- I have done a few of them. You can not even start a project like this unless you have a speed tape and the other equipment to measure the output. An I phone is not going to cut it as you need a reference tape to work from. The specs for the KD-2B are 2000 and 4000 RPM and the original might have been 1600 and 3200RPM depending on model. These 4 terminal motors do not have internal adjustments.