Sony TC-208 Eight-Track Deck

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Replaced the belt on this deck (after spending well over an hour  
cleaning out the tar-like goo that the old one had gone to). Completely  
cleaned the head, trip-sensor & capstan w/ Q-tips & alcohol. Great, deck  
worked fine for about a week, but has now developed an annoying flutter  
(speed-variation) problem. Doesn't matter which cartridge I play,  
happens w/ them all. So, after looking at the rather-spartan service  
manual, I put a voltmeter across the motor to check for variations. The  
manual states that there should be 20VDC across it. Running it w/o the  
belt, it shows a steady 21.2V (so, no-load). But when I run a tape, I  
notice the meter changes a few tenths-of-volt whenever the speed varies  
(so w/ load, since I can cause the same under no-load by pressing down  
on the pulley). Which makes me wonder if the capstan needs a clean-out  
of old grease at its bearing. Would love to, but there's an E-clip  
*under* the flywheel the holds the whole assembly in place. Would love  
to know -- how-in-hell -- I'd remove that E-clip (the service manual  
gives no such information)? Anyhow, if anyone has worked on this or a  
similar Sony model (TC-228, 258, etc), could you please provide some  
insight?

Re: Sony TC-208 Eight-Track Deck

Lubrication issues? Sounds like the capstan might be wobbling in the bushin
gs.  
If the belt turned to crud you can be certain the lubes are bad too.
Sony is notorious for using lousy lubricants even in $100,000 broadcast
machines.



Re: Sony TC-208 Eight-Track Deck
snipped-for-privacy@yahoo.com wrote:

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Not sure about this but figured I'd toss it out.

Didn't most of the 8-track players use a self-regulated dc motor?

I don't remember what the exact name was but they were 12v dc motors that
had a built in regulator/speed control and you normally applied 14~20 volts
to them.

Usually on the flat side (opposite the shaft out side) there was a label
covering up a hole for a pot, to set the speed.

Although after all these years it probably is a bering/lube problem but the
fact that it worked a week or so before this symptom cropped up, seems a
little strange.

Kind of have a feeling it's something with the regulator circuit board
inside the motor, which even back in the day means the whole motor needs to
be replaced. Seemed like trying to take them apart pretty much destroyed
them.

Just a thought.

-bruce
snipped-for-privacy@ripco.com



Re: Sony TC-208 Eight-Track Deck
After a bit of hair-pulling, I was able to remove the E-clip holding the  
assembly. Relubed it w/ white lithium grease, but it didn't make much of  
a difference.

Regarding the motor, yes it uses 20v (outlined in the service manual) &  
has a rubber plug on the bottom, but I can't figure out how to get it  
out. W/ a voltmeter across the motor, & running w/ no load, I get a  
steady 21.2V. Would the voltage vary if the motor had speed issues? It  
does do so, under load, in time w/ the audio fluctuations. But I can  
also make the voltage drop under no load by pressing down on the pulley.

Another possible problem is that the center of my capstan is quite worn  
smooth. A website (8trackavenue.com) suggests "roughing" it a bit w/ a  
scouring pad inserted into the front of an empty cartridge. Gonna give  
that a try, too.

Strangely, the deck will play w/o any trouble if I turn it over sideways.

On 10/12/2015 7:54 AM, Bruce Esquibel wrote:
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Re: Sony TC-208 Eight-Track Deck
On Monday, October 12, 2015 at 7:44:43 AM UTC-6, Madness wrote:
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Almost 40 years ago, when I used to fix these things for money, it was almost always a traction problem caused by the capstan being overly polished.  I tried fine emery cloth, but what worked great was:
- remove the capstan with its drive pulley.
- put it on a record player turntable and get it spinning.
- heat up the polished part of the capstan shaft with a propane torch until it would glow dark red for a few seconds.
    - the spinning is an attempt to prevent warpage.
- let it cool and reassemble.  

The surface will now be a dull matte finish and the traction problem is gone.  Never had to do it more than once in the life of an 8-track player.

Hope this is of interest.

Re: Sony TC-208 Eight-Track Deck
On 11/10/2015 01:25, Madness wrote:
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Is the wow cyclic? any repeat period could indicate where.
What state the pinch wheel, hard,soft,flatted? can you invert it  
,initially before replacing, and see if it makes a difference, also  
changing the applied tension by finger pressure.
Are you sure you've removed all the ex-rubber black goo? it is  
annoyingly persistent stuff, it could trail in from somewhere unseen

Re: Sony TC-208 Eight-Track Deck
On 10/11/2015 3:46 AM, N_Cook wrote:
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I pretty sure that I've gotten all the goo out. Most had centered on the  
motor pulley & the flywheel. As for the "pinch wheel," those are built  
into each cartridge. Any idea on how I could remove the E-clip holding  
in the flywheel/capstan?

Re: Sony TC-208 Eight-Track Deck
On 11/10/2015 16:12, Madness wrote:
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Piece of cotton tied to it and then a dart point or  dental sickle probe


Re: Sony TC-208 Eight-Track Deck
On 10/11/2015 11:28 AM, N_Cook wrote:>
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The dental probe sounds like a good idea. Might get better access if I  
remove the front panel. Incidentally, if I turn the deck on its side &  
play a tape, there's no flutter.


Re: Sony TC-208 Eight-Track Deck
Sloppy capstan bearings. Look see how they're mounted. Usually there are th
ree screws. If it is not too terribly bad you can rotate the bearings, some
times that will work, others not. If not, you'll have to push the bushings  
out and find a machine shop. Actually you'll have to take them the whole th
ing, they can push them out.  

Years ago when these things were plentiful it would not be worth doing, but
 now that they are a rarity it might be. I don't now what a machine shop or
 machinist would charge, but it is not going to be five bucks.  

My lathe was bigger and would not hold the tolerance for this, plus I sold  
it recently. But really, to be fair as a private guy, not a shop I would pr
obably do it for like $30. Shops generally have a per hour figure for each  
machine, you got a few minutes to cut the stock and not more than an hour l
athe time.  

The way to check this is to try to move the flywheel. It will most likely m
ove in one direction, to and fro in relation to the front of the unit. If y
ou turn the bearings, keep in mind which way the force will be. It is pulli
ng the tape to the right, and it is worn in the back at the top and maybe a
 little at the bottom. You want ti oriented so that the force does not skew
 the capstan which will give you even worse problems. Think about which way
 it was going and the force of the tape, then decide which way to turn it.
  

There is a possibility that due to the mounting arrangement you cannot turn
 the whole bearing. If this is the case then you have to push out the bushi
ng(s)and just rotate them. Mark EVERYTHING.  

Also, if the top and bottom are identical, instead or rotating them, keep t
hem in the same position but switch them.  

We used to scrap units over shit like this, but no more. You can easily get
 $200 to fix a betamax now. If you can actualy do it that is ...

(I just noticed the word "betamax" is marked by my spellheck, how dare they
 ! I HAVE a betamax !)

Re: Sony TC-208 Eight-Track Deck
On 11/10/2015 18:34, Madness wrote:
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Attitude effect suggests a bearing problem. Assuming sintred metal  
bearing , you can sometimes get a bit more life from the following.
Squash the bearing between 2 tiny ball bearings , set in a pair of nuts  
or something, squashed in a vice. Matter of suck-it-and-see. Try low  
force initially and try out with the capstan and repeat with gradually  
increasing vice force

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