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Only One Spindle Moving in Play (FF/RR Work)

Deck Problem

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#1 Mike

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Posted 25 May 2015 - 01:55 PM

So I went to Florida for a vacation and unfortunately an unexpected funeral.  Anyways...when I got home I went right to my JVC M90 that I had been missing.


When I pressed play only the left spindle moved, which causes the deck to eat the tape (fixable).  Both FF and RR work perfectly, which I found odd.  Doesn't the motor only operate a single spindle?


I unfortunately can't press play, FF, or RR without a cassette in the deck.  So I can't get a better look on what is happening.  Any clues here?  Should the motor operate both spindles?  How could a spindle get "locked up"?  I'm baffled by this one.  I can't find anything on this forum regarding this topic.


I've not yet opened up my M90.  I've opened up and done some work on all my other boxes.  I plan to open the M90 sometime next month.




#2 blu_fuz

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Posted 26 May 2015 - 08:05 AM

It is actually a dual motor design. There is one that drives the flywheel and needs a belt, the other is a direct drive setup with gears on the shaft. Not sure which one does what, but maybe the likely culprit is the flywheel belt is stretched or off and needs to be replaced.

#3 Mike

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Posted 31 May 2015 - 09:19 PM

Thanks as always Blu_Fuz.  I'm looking forward to opening up my M90 (after my telefunken, see below).  Hopefully it is just a belt.  What's odd is that the "tech" I used in Berkeley CA (~3 months ago) said he changed all the belts.  If he did...he didn't do a good job obviously.  It is just odd to me that all the other deck functions still work.  I also never realized that both spindles can be operated simultaneously.....I thought the motor only drove a single spindle and the other just moved "in-sync".  But it makes sense that the M90 motor should drive both spindles as the "broken" spindle is completely locked up and won't even turn if I use my fingers.


So I said I was going to try to open my telefunken studio, and I started today!!  I opened every bolt I could find (and got all the knobs off with allen wrench).  The face would not open.  It is only stuck at the right, middle, side of the box (just to the right of the volume knob).  All other parts of the face want to come right off.  Since it wasn't happening I then opened up the back of the box.  I tried a few different bolts from the back...but nothing helped.  I took a few pictures.  Anyway you can tell where this mystery bolt is so I can get the face off?  The manual I have doesn't help with this.


Also, see those two fuses?  If I replace them, should the lights work?  I ask because the battery meter light doesn't work.  It would be awesome if that's all I need to do to fix.


Ohhh...and the reason I opened up is to LEARN and to replace the belts.  The cassette deck is playing SLOWWWLLLLLYYYYYY.  I'm hoping this is more difficult then my Toshiba RT-8290S or Prosonic box...because they were easy!


Thanks for the information as always!!!

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#4 baddboybill

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Posted 04 June 2015 - 11:06 AM

M90 = the direct drive motor is for ff and rew and the belted motor is for play mode

#5 baddboybill

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Posted 04 June 2015 - 11:11 AM

I believe the nut on volume control needs to come off on Telefunken and the lights are most likely blown for tuner/meters

#6 burtron5000

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Posted 10 June 2015 - 12:45 AM

I'm having the same problem with my M90, except the right spindle will turn sporadically in play mode. But it most definitely doesn't turn smoothly and ends up eating any tapes I try to play. I just changed the belts and all other functions work.


Also, when the tapes I've tried do play, they play slower than normal. Is there a away to adjust the tape playback speed on an M90?


Thanks - I've only had my M90 for a couple weeks so I'm still trying to figure it out and get it as close to fully-working as possible.