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Cassette head reversal problem

Well heads rotate perfectly well on both decks , Aiwa AD WX 888 but going in batches , for each deck, either tape will not change direction , or will work consistently ie unreliably, mostly unreliable. Drops into an illegal mode where both spools are powered in opposiste directions and both pinch wheels are engaged , so likely to stretch or break tapes. This action is initiated by a solenoid then PTO mechanics , perhaps one flip for normal play in whatever preceeding direction set before stopping . Then longer pull or 2 pulls or something more complex to change direction of play , not explored yet manually. Could this rely on a timing adjustment somewhere that would apply to both decks ? I have replaced both drive bands and the speed of both decks is as good as I can get them via strobing and test tape.

Reply to
N_Cook
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Normally this is only possible on a dual-flywheel single direction deck with the belt threaded wrong.

If this one were to use motor reversal during reverse play, perhaps the capstan belt could be threaded wrong after all?

Mark Z.

Reply to
Mark Zacharias

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Then it would never work correctly. If anything when either deck works correctly and considtently with multiple reversals then the tape is near the end of its run, as if only allowable for reversing at the end of a side , but the problem will occur at the end of the tape sometmes, ie not reversing . Both deck bands were stretched, 1 band per deck ,not broken, so I could mark the path of the bands to avoid that problem. Both motors run continuously in one direction only. It is dual capstan , one motor per deck. Unfortunately I have got waylaid with more urgent stuff to look at. I doubt its a RTFM thing (not present or repair manual), ie not allowed to change direction in mid-tape as allowing a mode to stretch tape would be very suspect.

Reply to
N_Cook

There is no preset associated with the solenoid energizing area. With bench 12V to the motor , manually pulling in the solenoid, under the motor ,produces Play mode in normal direction for duration of soldenoid held in. A momentary pull and release flips the head rotor to reverse posistion but deck stays in neutral. A pull in , partial release, pull in and hold , engages Reverse Play. Pull in momentary , full release momentary, pull in and hold , normal Play I sometimes manually have been able to put it in the jam mode, easier if driving the motor off 4V or so, but not at all obvious what is different in that initiation. I'm wondering if a wrong voltage is getting to the solenoid, either pull in or maybe a negative pulse for the partial position. Whatever the solnoid drive is, then if it is wrong then would explain why both decks are affected, lack of lubrication or wear on the most used Play-only deck would not throw up this jam mode on both decks. I won't try scoping these solenoids as I've spent enough time on this diversion and the owner is happy with just normal Play with both decks. Perhaps both replacement bands are just not tight enough and slips on the PTO pulley enough to mess things up. As the replacement bands were spot on the existing motor speed preset via test tape and strobing , I will just roughen the PTO pulley of both decks and leave at that. The slip clutch inside the PTO pulley seems slack to me perhaps, something else to consider if there should be a next time.

Reply to
N_Cook

I don't know if it comes under William of Occam's raison (13th century Occam, Surrey , England did not have razors at the time - later mistranslation from French) or the more modern version K.I.S.S.

Roughening of the surface of the PTO pulleys returned reliable service for normal/reverse play modes.

Reply to
N_Cook

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