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Thread: Tascam 38 inconsistent playback/record

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    Tascam 38 inconsistent playback/record

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    Hello all

    First post here – i'm very happy to find a group so dedicated to the my same interests.

    Question:
    Recently in the middle of a session with my Tascam 38, we noticed that the machine was suddenly playing/recording at an inconsistent speed.

    Meaning, when we repro'd back what we had just done, the pitch wavered up and down. Also, the pull knob for playback pitch control stopped working as well, doing nothing.

    Ive popped it open and the belt seems just fine.
    Im wondering if it might be the capstan motor – some sort of wear that is causing it to turn without a consistent speed?


    Many thanks in advance!

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    Usually it's either the belt becoming slack, or the pinch roller not pressing hard enough. Or the pinch roller turning to mush. A belt issue wouldn't explain the lack of varispeed, but even so, unless the belt has been replaced within the last couple of years, I would start there to begin with.

    It might also be worth pressing the roller against the capstan while recording a test tone and again while playing it back to see if that improves things. If that does make a difference, try measuring the pinch roller force using a spring scale. There's usually a way to adjust it if that turns out to be the problem.

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    Yeah capstan belt goof bad, pinch roller pressure too low, pinch roller going soft -OR- pinch roller too hard...dried out.

    Check those things first.

    That weird on the varispeed not working...hmmm.

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    Quote Originally Posted by sweetbeats View Post
    That weird on the varispeed not working...hmmm.
    If it's a pinch roller pressure problem, the tape might be moving largely by virtue of the reel motor tension instead of the capstan, in which case the speed control isn't going to do much. Either that or there genuinely is some weird problem with the capstan controller.

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    Quote Originally Posted by sweetbeats View Post
    Yeah capstan belt goof bad, pinch roller pressure too low, pinch roller going soft -OR- pinch roller too hard...dried out.

    Check those things first.

    That weird on the varispeed not working...hmmm.
    Thanks much for the replies.

    Something else i should mention that i just noticed after some tinkering is that the capstan has some horizontal give / travel, meaning its not sturdy like my back-up T38, but it can be pushed forward and backward. You can see more of the shaft than you should before the gold ring and push it in or out

    38ca_2-jpg

    I can see now is causing the pinch roller to lock-up and not play at all. When the pinch roller is locked up, if i give a little push on the flywheel on the side of the motor itself, the pinch roller will start spinning too when engaged in playback.

    All this being the case, seems like it could very well be related to my problem.


    Thank you!
    Sean

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    I’m not certain about the play you are talking about. The spare 32 capstan and flywheel assembly I have here has play in it, like about 0.100”. I think this is normal. The play gets addressed when you adjust it. There’s supposed to be a small amount of play between the rear bracket and the tail of the capstan shaft. Check the service manual. It specifies what thickness feeler gauge you use to measure the proper play between the tail of the capstan shaft and the bracket.

    But I’m really curious about this locking up business. Are the set screws secure between the flywheel and the capstan shaft? Is the pinch roller binding up? It should be smooth and turn freely even when applying axial pressure.

    Is this the same Sean from I bought an Ampex AG-440B-8 about 10 years ago?

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