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Thread: Has anyone replaced a motor in a 388?

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    Has anyone replaced a motor in a 388?

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    The "left" motor in my 388 is dead... when I press Rewind, it seems like it tries to get going, but stalls. I have to manually rewind the tape, which isn't a huge deal, just annoying and not acceptable in the long run. Play/Fast Forward work perfectly.

    I don't have the money to take it to the shop, and wanted to know what it's like to change out a motor. I'm not a mechanical genius, but I can follow directions pretty well. Is this a beast of a job or doable?

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    Arrow Man, that's a lot of hand winding!

    Probably covered before, but you want to make sure it's not a "sticky" tape that's prohibiting the rewind function. Sticky tape is to blame for many transport issues, as it's proven over time.

    If you feel adventurous, there's a moderate disassembly to take the face plate, deck plate, or whatever you want to call it, from the face of the reel-to-reel transport. Once under this cover, you'd want to verify the brakes are releasing fully when tape's put into motion.

    Beyond that, I'd venture to say that if you suspect a bad motor, it's likely one bad, or a pair of bad drive transistors, (2 transitors drive each reel motor), more than the motor. Just by probability. Unfortunately, that's a techy repair that doesn't lend itself to basic DIY efforts.

    The description of "tries to get going but stalls" has me suspicious of bad tape. It depends on how much it "tries" before giving up. If it goes a second or two, I'd suspect bad tape (or servo adjustments). If it moves a split second and goes entirely limp, losing tape tension, I'd suspect motor drive transitors.

    (As mentioned), the reel/servo electronic adjustments could be off, which would directly affect the FF or RW function. As a rule of thumb,... the centers of the Left and Right Tension Rollers should intersect on a plane that's even with the tops of the Idler and Tach roller, left and right respectively, when in Play mode. Picture it,... or consult the manual. If the rollers don't have this configuration, it would indicate that the reel/servo electronics need adjustment. The good news is it's relatively easy. Again, consult the manual.

    The 388's a nice unit, but there's a lot going on in the box.

    /DA
    Last edited by A Reel Person; 02-02-2009 at 14:07.
    Quote Originally Posted by Lt. Bob
    ... subtleties of sound make a difference to those who really listen.

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    I agree with Dave, sounds like dirty travel-path and tension rollers.
    Not often a motor goes bad, can you post a couple of pictures of the headstack and tension rollers maybe ?

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    Thanks guys. I guess it could be sticky tape... I'll have to research that a bit to know what I'm looking for.

    Basically the same problem occurred using brand new RGMI reels as well as "older" new 406 reels (I don't have the year on those at the moment - I know the 406's are slightly thicker than the 388 wants).

    When I hit REW, it starts to move and dies (probably gets about 5-10% of one rotation...tension seems to hold. I manually rewind with REW engaged, and on occasion it's picked up from manual spinning momentum and continued for a little while to rewind un-assisted... maybe two or three times. Mostly it just glides slowly to a halt.

    Oh, and I did have it in the shop (ProTech in Silver Spring, MD)... A friend gave me the 388 and told me it needed a new belt... so I took it straight to the shop and they confirmed it needed a new belt. They replaced it and did the basic tune up (cleaning rollers, etc.). Invoice says they performed an equipment test (recording, basic functions), but didn't mention the REW issue.

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    Arrow Survey says"...!!!

    1) Bad tape/dirty tape path
    2) Reel/Servo adjustments
    3) Not the motor or drive transistors

    Virtually any tape can be sticky, regardless of make or production run,... when you get down to it. By your description and using new RMGI tape, I'd be a bit less inclined to think tape & would focus on the servos. A badly aligned servo could just kill the FF/RW function. The postion of the rollers, as per the above, is a good indication of the servo balance or unbalance, whichever the case may be.
    Quote Originally Posted by Lt. Bob
    ... subtleties of sound make a difference to those who really listen.

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    Hmm, this is a long-shot but check the reel-table height between L + R table, if the left table maybe pushed in too far, the brake-band can rub against a rubber ring located on the upper part of the table and create slow movement

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    Thanks y'all. I've got a few good leads from you guys.

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    Any luck ?

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    Vintage: I like your "long shot" idea... It will likely be this weekend before I put some investigative work on this. I'll definitely let you know what I find and if I solve the issue. Much appreciated!

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    Sounds good, let us know what you find

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