ms 16 slow to rewind

[mr c deckard]

hey, i hit rewind and the machine immediately stops. is this an
indication that the rewind motor is going bad? if i twist the left
reel with my hand to help it accelerate, it's ok. or could it be an
adjustment?

thanks,
chris deckard
saint louis moe

[Cerion]

Hi,


Since I've never seen that particular problem on an MS16 I can only offer
things to check:

I'll try to list stuff in their respective order according to probability of
occurring.




Ideas:

> Dirty trim potentiometers. Old potentiometer or trim pot wipers get
corroded with sulfides or other stuff due to chemical reaction, which in
turn effects intermittent function or drift. This problem almost always
occurs with older stuff and especially where the machine has been exposed to
lots of outside air or no climate control.

> Dirty trim pots for the Reel Tension adjustment or Winding Speed
adjustments could adversely affect winding speed and torque.



The MS 16 allows you to adjust these things separately:

>Fast Forward Speed
>Fast Rewind Speed
>Supply reel Take-Up reel Tension.
These are all electrical trim pot adjustments. The tension adjustments are
kind of interesting in that without tape, the reel hub motors can actually
turn pretty fast in opposite directions if you bypass the interlock switch.
So if the pot(s) drift and there's too much tension that could cause slow
wind in one direction or both.


Other ideas:

> Bad connector crimp or joint in the drive transistor to motor cable
causing current limit to motor.

> Failing motor drive transistors or their respective emitter or collector
resistors

> Low power supply voltage or current limiting due to regulator failure,
leaky cap(s), bad rectifier(s), bad transformer.

> Of course a bad motor is a possibility. But if it were my machine, I'd
check the electrical chain that drive the motor first.



Good luck! :-)


Skyler

[Justin Ulysses Morse]

Try it without any tape on the machine (you might have to hold a dancer
arm up or stick a card in an optical sensor). Does it spin without a
load?

ulysses


In article >, mr c
deckard > wrote:

> hey, i hit rewind and the machine immediately stops. is this an
> indication that the rewind motor is going bad? if i twist the left
> reel with my hand to help it accelerate, it's ok. or could it be an
> adjustment?
>
> thanks,
> chris deckard
> saint louis moe

[Justin Ulysses Morse]

mr c deckard > wrote:

> thanks for the replies, all. i did check it without tape, and the
> reels spin as they should (although i don't have a tentelometer) . . .
>
> to make things worse, it seems to be intermittent . . .

Good. Your motor is fine. The problem could be bad wire or connector
on the motor, but it's more than likely the control circuitry. You
just have to narrow it down more.

Does the supply reel ever do anything to **** you off while playing or
recording or fast-forwarding the tape? It might be somewhat difficult
to tell, since these basic functions might still exist without the
supply reel behaving properly.

I'm not familiar with the MS16 in particular, but I'm all to familiar
with the general topic as it relates to my MCI machine.

Is there a dancer arm between the supply reel and the headstack? If
there is, then you can get a decent visual check of the supply
backtension during playback by looking at the dancer arm. If it gets
pulled too tigh and rests against its stop, you have too much back
tension. If it is at or near the "slack" end of travel, you don't have
enough. Explore this or whatever other methods you can find to see if
the supply reel ever fails to pull during other modes (During playback,
there's supposed to be a small amount of reverse tension on the supply
reel so it doesn't dump a bunch of extra tape slack into the
headstack).

By narrowing down the particular modes of operation where the problem
exists, you can narrow down the portion of the control circuitry
(called the analog torque board on my MCI) that is to blame. Some
portions of the circuit are used just for rewind, some are used in all
modes. Do you have the manual w/ schematics for this machine?

Another possibility is that the reel brake bands are failing to
disengage due to improper tension, a bad solenoid, or bad control
circuitry. But the most likely problem is that the backtension needs
to be adjusted, and it's causing a problem in playback and FF that you
just haven't noticed yet.

ulysses

[Cerion]

Hi,


* Side mounting doesn't make any difference
* The AutoLocator has nothing to do with the problem

* One of the previous posts offered a very excellent and practical
suggestion:


With equal amounts of tape on each reel and in the edit mode, the tape
should shuttle easily by hand, i.e. moving either reel by hand should result
in the motors tracking each other and require very little effort. If the
machine does not behave this way, that is with relative ease in the edit
mode, then the tape tension on one or both reels needs to be re-adjusted.
Clean the trim pots!


The problem you describe, where the machine jumps out of play, would
indicate to me that the tape tension is insufficient. What could be
occurring is that when the machine is trying to start up, the tension
oscillates a bit and the tension arm interlock switch is jiggled enough to
shut the machine off. Although I have seen this on the MS16 I used to
have, it wasn't really a problem, but only appeared during the process of
fiddling around with the tension adjustment to see how it behaved. I'm
thinking it might be out of whack on your machine though... Hey, it's worth
checking out! Very easy to adjust. I don't remember too well, but I think
you have to remove the bottom panel to access these trim pots. By way of the
trim pots, you can independently adjust the tension on each reel, plus the
fast and slow wind speeds. I do recall that even if you're in the
braked-stop mode, you can see the tape tension arms move according to static
tension while adjusting their respective pots and kind of roughly gauge the
tension by the relative position of the arm. Without a fancy tape tension
gauge though, you just have to play around with it and try all kinds of
shuttling and starting and stopping and make sure it's wrapping clean, etc.

:-p

Skler



mr c deckard > wrote in message
om...
> again, thanks for the replies all. the machine works fine in all
> respects, but it seems to be having a hard time getting up to speed
> when the reel is full -- i.e., it seems to have a hard time rewinding
> when the supply reel is full, it seems to have a hard time getting
> into play when the takeup reel is full. a few details: this machine
> is side mounted (ie the reels are vertical). also, the problem is
> that when i hit play (eg), the green play light lights up, the machine
> attempts to play, but it immediately goes into stop mode, as if i hit
> play then stop 1/2 sec later. i'm also using an aq-65 autolocator,
> but i suspect that it's not the problem.
>
> later tonight, i'll put a tape on it and to the 16:40 edit test jp
> suggested.
>
> thanks again,
> chris deckard

[Justin Ulysses Morse]

Do you have the manual? Tascams from that era have unbelievably
thorough and useful technical manuals. It will guide you specifically
through the exact steps for calibrating the tape tension on your
machine. After doing that, if the problem still exists, then it'll
guide you through troubleshooting to find out what needs repair. Keep
reading and it'll explain the entire concept of the decibel from its
inception to current use.

ulysses


In article >, Cerion
> wrote:

> Hi,
>
>
> * Side mounting doesn't make any difference
> * The AutoLocator has nothing to do with the problem
>
> * One of the previous posts offered a very excellent and practical
> suggestion:
>
>
> With equal amounts of tape on each reel and in the edit mode, the tape
> should shuttle easily by hand, i.e. moving either reel by hand should result
> in the motors tracking each other and require very little effort. If the
> machine does not behave this way, that is with relative ease in the edit
> mode, then the tape tension on one or both reels needs to be re-adjusted.
> Clean the trim pots!
>
>
> The problem you describe, where the machine jumps out of play, would
> indicate to me that the tape tension is insufficient. What could be
> occurring is that when the machine is trying to start up, the tension
> oscillates a bit and the tension arm interlock switch is jiggled enough to
> shut the machine off. Although I have seen this on the MS16 I used to
> have, it wasn't really a problem, but only appeared during the process of
> fiddling around with the tension adjustment to see how it behaved. I'm
> thinking it might be out of whack on your machine though... Hey, it's worth
> checking out! Very easy to adjust. I don't remember too well, but I think
> you have to remove the bottom panel to access these trim pots. By way of the
> trim pots, you can independently adjust the tension on each reel, plus the
> fast and slow wind speeds. I do recall that even if you're in the
> braked-stop mode, you can see the tape tension arms move according to static
> tension while adjusting their respective pots and kind of roughly gauge the
> tension by the relative position of the arm. Without a fancy tape tension
> gauge though, you just have to play around with it and try all kinds of
> shuttling and starting and stopping and make sure it's wrapping clean, etc.
>
> :-p
>
> Skler
>
>
>
> mr c deckard > wrote in message
> om...
> > again, thanks for the replies all. the machine works fine in all
> > respects, but it seems to be having a hard time getting up to speed
> > when the reel is full -- i.e., it seems to have a hard time rewinding
> > when the supply reel is full, it seems to have a hard time getting
> > into play when the takeup reel is full. a few details: this machine
> > is side mounted (ie the reels are vertical). also, the problem is
> > that when i hit play (eg), the green play light lights up, the machine
> > attempts to play, but it immediately goes into stop mode, as if i hit
> > play then stop 1/2 sec later. i'm also using an aq-65 autolocator,
> > but i suspect that it's not the problem.
> >
> > later tonight, i'll put a tape on it and to the 16:40 edit test jp
> > suggested.
> >
> > thanks again,
> > chris deckard
>
>
>

[Michael Kovach]

He has, at least HAD, the tech manual, I sold him the machine a few years
back.

Is your tape shredding excessively? Check for oxide or tape bits that are
getting into the capstan, wheels or motors. It might just need a thorough
cleaning.

Mike

"Cerion" > wrote in message
...
> Hi,
>
> When I sold my machine the manual went with it. Unfortunately, I'm
certain
> I no longer have the electrical schematic, and that's the most important
> part of the manual. :-p
>
> A service manual for the MS16 is definitely worth pursuing.
>
> I've been hard disk recording for a few years now and becoming accustomed
to
> that environment, but you know, I still think the analog machines sounded
> great in comparison, kind of effecting their own signature distortions,
and
> sounding especially good with percussion and bass instruments. The 4
track
> cassette, 8 track 1/4 inch and 8 track 1/2 inch (model 38) Tascam machines
> of the 80's generation were particularly excellent sounding, very warm,
> natural sounding, very nice. The MS16 is a little more transparent than
the
> smaller format Tascams, but an excellent and natural sounding machine just
> the same.
>
> Skler
>
>
>
>
>

[mr c deckard]

hi mike -- good to hear from you. i do indeed have the manual (i try
to get scehmatics/manual for all the gear, ESP. the tascam stuff, they
really are extraordinary manuals).

to be honest, i sent the original post during a smoke break on a
session -- it really hasn't been doing it recently . . . i'll have
that same reel on there tomorrow night, so i'll check out the shed
issue. it's kinda puzzling since the machine seems to be in perfect
health . . . it's still going strong.

best,
chris




"Michael Kovach" > wrote in message >...
> He has, at least HAD, the tech manual, I sold him the machine a few years
> back.
>
> Is your tape shredding excessively? Check for oxide or tape bits that are
> getting into the capstan, wheels or motors. It might just need a thorough
> cleaning.
>
> Mike
>