Ampex F4460 reel to reel.

[Mark Zacharias]

"Sjouke Burry" <burrynulnulfour@ppllaanneett.nnll> wrote in message
news:5493c99f$0$28003$703f8584@textnews.kpn.nl...

On 19.12.14 4:16, captainvideo462009@gmail.com wrote:
On Wednesday, December 17, 2014 12:53:27 AM UTC-5, captainvi...@gmail.com
wrote:
I'm working on my old Ampex 4460 reel to reel machine. (work is slow),
and I'd like to listen to some of my old tapes. I cleaned and lubricated
it, demagnetized the heads and put a tape of some familiar music on, and
I thought it seemed a bit slow. So I repeated it with other tapes and
then followed with an Ampex frequency response alignment tape. The scope
was calibrated to 1.0ms off the 1KHZ square wave output and then I
looked at the the 1KHZ sine wave off the tape. The period was
approximately 1.40ms which appears to translate to 714HZ. Truly hard to
believe that it's running that slow, but I don't think that the
equipment is lying.

So I next got out the Strobeotac and put it on the motor capstan. The
motor is rated for 1850 RPM at 115V, and it's running rock solid at
1795. I tried loading it while watching the speed and it remains steady,
so it doesn't appear to be a load problem. Could such a slight motor
speed reduction cause a 25 percent reduction in the frequency of my 1KHZ
test tone off the tape? It doesn't seem possible, but I don't know.

The motor has a label that reads that it uses a 3.0UF 330V capacitor. I
haven't investigated this yet, but with four wires going into it I
figure that the cap must be on the chassis somewhere. I wouldn't think
that a cap problem though would cause my RPM's to drop 55RPM would it?
Oh and I have no service manual, however I don't think that service
manual would do me much good with this problem anyway.


If anyone has any thoughts on this I'd sure appreciate hearing them.
Thanks, Lenny

In the early 1970's I was the service manager for a broadcast and
recording equipment company. I worked on a lot of Ampex, Scully, Revox,
etc. professional machines. This unit, the F4460 although an Ampex was
built for the consumer market. and although the electronics was superb,
just about up to par with the professional machines, the transport
however left a lot to be desired.

To keep the costs down, (under a grand at the time, I think) they had to
chinch on something, and it was the deck. The studio machines employed
three motors. There was a main, and also a take up, and a hold back
motor. These two torque motors would not spin during normal operation but
were used to maintain proper tape tension on the heads.

Ampex had a few of these consumer type machines on the market at the time
that used similar other cheaper techniques to try to accomplish the same
thing as the pro machines. For instance Instead of a take up torque motor
there was a slipping clutch on the take up pulley. And for hold back
tension, instead of a motor tensioning the tape across the heads a felt
washer jammed the tape against a guide on the left side of the machine.
This washer would eventually load up with tape material, the transport
would start wowing and the washer would have to be removed, cleaned with
alcohol and reinstalled. A pain in the ass but worth it to have an Ampex.

I didn't ever really recall ever having a speed problem like I'm having
with mine with one of these consumer type machines, or even ever having
to check speed as referenced from an alignment tape as I did here with
the scope. They just always seemed to be on speed.

So Jurb to answer some of your questions, or suggestions, yes I am in the
US, New Hampshire to be exact. We haven't seceded from the Union yet,
although sometimes I wish we would. I tried checking RPM both ways;
unloaded and then loaded with belts capstan engaged, and then
"overloaded" (the finger on the pulley test). And through it all the
motor maintained constant torque and speed. Both the motor and flywheel
turn freely. The motor actually has two fill holes for each bushing. I
was able to stick a hypo filled with 10W into each hole and hit what
seemed like a felt sponge around an oilite bearing. Besides if either one
of these items was stiff I would expect to see a speed fluctuation
problem, which I don't. The capstan bushing is also tight. Other than
that I can add that this machine had a very easy life before I acquired
it. It was hardly used at all. Tomorrow I'll play with the cap value and
see what happens.

Really thought this thing would be off my bench by now, and back in the
entertainment center and I'd be listening to my Grateful Dead tapes.
Fucken bummer. Lenny

Maybe a silly suggestion, but check your scope 1khz signal.
Because those are not very reliable signal sources, specially
in old scopes. The square wave is usually oke, but the frequency
might be off. Maybe your voltmeter has a frequency measurement range.

I have seen older machines run slow because the idler wheel has dried out so
much that it's circumference has actually contracted noticeably.

Also, do not rule out an issue with the motor pully - the idler could be
running at a slightly lower height, if the pulley has a curved face. The
motor mounting bushings could be deteriorated, causing a height issue.

In my experience - if it were the motor cap, it would slow down and stop.
Also, the cap would probably be leaking noticeably, possibly also getting
hot.


Mark Z.

 

[Tim Schwartz]

On 12/17/2014 12:53 AM, captainvideo462009@gmail.com wrote:

I'm working on my old Ampex 4460 reel to reel machine. (work is slow), and I'd like to listen to some of my old tapes. I cleaned and lubricated it, demagnetized the heads and put a tape of some familiar music on, and I thought it seemed a bit slow. So I repeated it with other tapes and then followed with an Ampex frequency response alignment tape. The scope was calibrated to 1.0ms off the 1KHZ square wave output and then I looked at the the 1KHZ sine wave off the tape. The period was approximately 1.40ms which appears to translate to 714HZ. Truly hard to believe that it's running that slow, but I don't think that the equipment is lying.

So I next got out the Strobeotac and put it on the motor capstan. The motor is rated for 1850 RPM at 115V, and it's running rock solid at 1795. I tried loading it while watching the speed and it remains steady, so it doesn't appear to be a load problem. Could such a slight motor speed reduction cause a 25 percent reduction in the frequency of my 1KHZ test tone off the tape? It doesn't seem possible, but I don't know.

The motor has a label that reads that it uses a 3.0UF 330V capacitor. I haven't investigated this yet, but with four wires going into it I figure that the cap must be on the chassis somewhere. I wouldn't think that a cap problem though would cause my RPM's to drop 55RPM would it? Oh and I have no service manual, however I don't think that service manual would do me much good with this problem anyway.


If anyone has any thoughts on this I'd sure appreciate hearing them. Thanks, Lenny

Good morning,

While I realized that the model is a F4460, is the machine what they
also call an F-44? The last 2 digits might just tell you what speeds or
cabinet the machine came in, or if it was 1/4 or 1/2 track.

Anyway, if it is an F44 (Fineline 44?) I have a recollection of what
Ampex techs call a "Dropped capstan flywheel" This is where the large
cast flywheel dropped down on the capstan shaft be cause the press fit
wasn't tight enough. I think you can check this by taking the top panel
off the unit so you can really see the flywheel, and just try pulling up
on it. If that's the case then you can take the whole thing out of the
machine, clean the capstan shaft and flywheel from grease, and refit the
flywheel with some epoxy so it stays where it it supposed to.

If this is an F44, contact me off-group. I might have a manual for the
thing somewhere in the archives.

Regards,
Tim Schwartz
Bristol Electronics

 

[Gareth Magennis]

"Phil Allison" <pallison49@gmail.com> wrote in message
news:ceb575a3-eda7-4259-9990-6306edd84c25@googlegroups.com...
Sjouke Burry wrote:

Maybe a silly suggestion, but check your scope 1khz signal.
Because those are not very reliable signal sources, specially
in old scopes. The square wave is usually oke, but the frequency
might be off. Maybe your voltmeter has a frequency measurement range.

** That might be the case OR the capstan roller has gone smooth and hard
with age and is failing to control the speed of the tape through the capstan
gate.

With this sort of defect, tape speed can increase or decrease, depending
whether the take up reel or supply reel has more torque. A simple test is to
see if it is easy to pull tape through the capstan gate with the machine
turned off - if it is, you have a problem.

Having serviced many Roland tape echo machines made back in the 1980s (the
famous Space Echo and Chorus Echo models ) I can say the one fault common to
practically ALL examples seen is a shiny, smooth pinch roller.

Since no new supply of suitable rollers exists, I fit the old one with a
suitable shaft and lock it into the chuck of a bench drill spinning at
600rpm - then, using finger pressure on a piece of fine sand paper wrapped
around strip of wood, gently remove the shiny surface & restore the needed
matt one.


.... Phil



This stuff is really good on pinch rollers.
http://www.amazon.co.uk/AF-International-Platen-Cleaner-Restorer/dp/B0012IKSHO/ref=sr_1_1?ie=UTF8&qid=1419000776&sr=8-1&keywords=platenclene


I once bought a bottle of Teac pinch roller cleaner, and it was totally
useless.



Gareth.

 

[Mike]

On Fri, 19 Dec 2014 14:56:02 +0000, Gareth Magennis wrote:

Since no new supply of suitable rollers exists, I fit the old one with a
suitable shaft and lock it into the chuck of a bench drill spinning at
600rpm - then, using finger pressure on a piece of fine sand paper
wrapped around strip of wood, gently remove the shiny surface & restore
the needed matt one.

But why does it matter? The pinch roller does not need friction to the
tape. It is the capstan that needs that. I can see you might need some
resilience so that the tape is not nipped too tightly and thus reduce the
contact pressure, but that's not really a surface attribute.

Mike.

 

[Gareth Magennis]

"Mike" <news@mjcoon.plus.com> wrote in message
news:T6qdnd5SDoGz3gnJnZ2dnUVZ8oadnZ2d@brightview.co.uk...

On Fri, 19 Dec 2014 14:56:02 +0000, Gareth Magennis wrote:

Since no new supply of suitable rollers exists, I fit the old one with a
suitable shaft and lock it into the chuck of a bench drill spinning at
600rpm - then, using finger pressure on a piece of fine sand paper
wrapped around strip of wood, gently remove the shiny surface & restore
the needed matt one.

But why does it matter? The pinch roller does not need friction to the
tape. It is the capstan that needs that. I can see you might need some
resilience so that the tape is not nipped too tightly and thus reduce the
contact pressure, but that's not really a surface attribute.

Mike.

I didn't write that, Phil Allison did.



Gareth.

 

[Phil Allison]

Mike wrote:

Phil Allison wrote:

Since no new supply of suitable rollers exists, I fit the old one with a
suitable shaft and lock it into the chuck of a bench drill spinning at
600rpm - then, using finger pressure on a piece of fine sand paper
wrapped around strip of wood, gently remove the shiny surface & restore
the needed matt one.

But why does it matter? The pinch roller does not need friction to the
tape.

** It absolutely does.

The simple explanation is in the words you snipped.


> It is the capstan that needs that.

** The capstan has no grip to the tape - since polished steel and smooth tape have no mutual friction.

I can see you might need some
resilience so that the tape is not nipped too tightly and thus reduce the
contact pressure, but that's not really a surface attribute.

** A shiny surfaced roller has no grip to the capstan.

Why the heck do you think pinch rollers ( along with idler tyres and drive belts) are made from soft rubber in the first place ?

You ever serviced a tape recorder in your life ?


..... Phil

 

[Jon Elson]

captainvideo462009@gmail.com wrote:

So I next got out the Strobeotac and put it on the motor capstan. The
motor is rated for 1850 RPM at 115V, and it's running rock solid at 1795.

1850?? How can the motor do 1850 on 60 Hz power? Many tape decks used
hysteresis-synchronous motors, so they were designed to spin up as
induction motors and then lock to the mains as synchronous.
A 4-pole motor would run at exactly 1800.0 RPM.

1795 with a strobotac is probably 1800, and your strobotac is
just a hair off calibration. You might just use a nean lamp
in series with a resistor and diode to make an exact 60 Hz
strobe, and see if a mark on the motor shaft stands still.


Jon

 

[Mike]

On Fri, 19 Dec 2014 13:58:10 -0800, Phil Allison wrote:

Mike wrote:

Phil Allison wrote:

Since no new supply of suitable rollers exists, I fit the old one
with a suitable shaft and lock it into the chuck of a bench drill
spinning at 600rpm - then, using finger pressure on a piece of fine
sand paper wrapped around strip of wood, gently remove the shiny
surface & restore the needed matt one.

But why does it matter? The pinch roller does not need friction to the
tape.

** It absolutely does.

The simple explanation is in the words you snipped.


It is the capstan that needs that.

** The capstan has no grip to the tape - since polished steel and
smooth tape have no mutual friction.

I can see you might need some resilience so that the tape is not nipped
too tightly and thus reduce the contact pressure, but that's not really
a surface attribute.

** A shiny surfaced roller has no grip to the capstan.

Why the heck do you think pinch rollers ( along with idler tyres and
drive belts) are made from soft rubber in the first place ?

You ever serviced a tape recorder in your life ?

No need to be rude! Actually I have only serviced special purpose players,
for a decade or three until they were discarded in favour of CD drives.
The media are all pre-recorded.

I said why I thought the pinch roller needed to be resilient; just a
matter of physics and pinch pressure. But now I see that you are relying
on an unstated but reasonable assumption: that the pinch roller is wider
than the tape so gets driven by the capstan on its margins and drives the
tape between those margins. You could, of course, have explained that
instead of ranting...

Mike.

 

[Phil Allison]

Mike wrote:
Phil Allison wrote:
:

Phil Allison wrote:

Since no new supply of suitable rollers exists, I fit the old one
with a suitable shaft and lock it into the chuck of a bench drill
spinning at 600rpm - then, using finger pressure on a piece of fine
sand paper wrapped around strip of wood, gently remove the shiny
surface & restore the needed matt one.

But why does it matter? The pinch roller does not need friction to the
tape.

** It absolutely does.

The simple explanation is in the words you snipped.


It is the capstan that needs that.

** The capstan has no grip to the tape - since polished steel and
smooth tape have no mutual friction.

I can see you might need some resilience so that the tape is not nipped
too tightly and thus reduce the contact pressure, but that's not really
a surface attribute.

** A shiny surfaced roller has no grip to the capstan.

Why the heck do you think pinch rollers ( along with idler tyres and
drive belts) are made from soft rubber in the first place ?

You ever serviced a tape recorder in your life ?

No need to be rude!

** Nothing rude about what I posted.

You clearly have no idea how a capstan tape drive works.

I said why I thought the pinch roller needed to be resilient; just a
matter of physics and pinch pressure.

** Makes no sense.

But now I see that you are relying
on an unstated but reasonable assumption: that the pinch roller is wider
than the tape so gets driven by the capstan on its margins and drives the
tape between those margins.

** Whaaaaattt - so you have never seen a capstan drive tape machine ?

Yet you still decided to argue with me about my clearly written, totally correct post, by snipping and ignoring the bits you completely misunderstood.

You could, of course, have explained that instead of ranting...

** The one rating is YOU - pal.

FFS - YOU could have admitted that YOU had no idea how a capstan tape dive worked instead of making guesses and bullshitting.

FYI:

The pinch roller is CRUCIAL to the operation - it traps the tape against the capstan shaft and resists tensions coming from the supply and take up reels. The roller's height is about twice the width of the tape so it contacts the capstan directly and is driven around by it.

The pinch roller is generally mounted on a spring loaded arm, which is held back opening a small gap unless the machine is in play or record mode. When in play or record mode, the spring loaded arm is released and holds the pinch roller firmly against the capstan trapping the tape in between.

The roller must have a flat surface, with a good amount of grip to the capstan shaft when engaged. It must also grip the tape and the shaft it turns on must be exactly parallel with the capstan itself.

A worn or old pinch roller typically has a "glazed" surface that has almost no grip to the capstan or tape - or else it may become barrel shaped. A barrel shaped roller skews the tape up or down the capstan, causing the tape to spill or wind around the roller.

With a cassette deck or VCR, the capstan drive mechanism is hidden from the operator - but with a reel to reel recorder or tape echo it is highly visible cos the tape must be manually threaded through the capstan gate.

As Pete Townshend famously said " .. the simple thing you see are all complicated ... "

Capice ?


.... Phil

 

[Cydrome Leader]

Phil Allison <pallison49@gmail.com> wrote:

Mark Zacharias wrote:

I have seen older machines run slow because the idler wheel has dried out so
much that it's circumference has actually contracted noticeably.


** Got some news for you - pal.

The exact diameter of an idler wheel is irrelevant.

Cos all any idler does to transfer the surface speed of one rotating object to another.

I have to admit that your explanations for pinch rollers is dead on. A worn or dry roller would cause slippage though, so rough it up and try again.

As for the OP, Not sure how much I'd trust a 400 year old tach. It may be time for a cardboard disc and a neon light to check for speed problems with the motor.
You don't need as many lines as on a turntable either.

 

[Tim Schwartz]

On 12/17/2014 12:53 AM, captainvideo462009@gmail.com wrote:

I'm working on my old Ampex 4460 reel to reel machine. (work is slow), and I'd like to listen to some of my old tapes. I cleaned and lubricated it, demagnetized the heads and put a tape of some familiar music on, and I thought it seemed a bit slow. So I repeated it with other tapes and then followed with an Ampex frequency response alignment tape. The scope was calibrated to 1.0ms off the 1KHZ square wave output and then I looked at the the 1KHZ sine wave off the tape. The period was approximately 1.40ms which appears to translate to 714HZ. Truly hard to believe that it's running that slow, but I don't think that the equipment is lying.

So I next got out the Strobeotac and put it on the motor capstan. The motor is rated for 1850 RPM at 115V, and it's running rock solid at 1795. I tried loading it while watching the speed and it remains steady, so it doesn't appear to be a load problem. Could such a slight motor speed reduction cause a 25 percent reduction in the frequency of my 1KHZ test tone off the tape? It doesn't seem possible, but I don't know.

The motor has a label that reads that it uses a 3.0UF 330V capacitor. I haven't investigated this yet, but with four wires going into it I figure that the cap must be on the chassis somewhere. I wouldn't think that a cap problem though would cause my RPM's to drop 55RPM would it? Oh and I have no service manual, however I don't think that service manual would do me much good with this problem anyway.


If anyone has any thoughts on this I'd sure appreciate hearing them. Thanks, Lenny

Hello everybody,

I doubt that his issue is a pinch roller no matter how badly glazed it
is as his machine is running SLOW, and it the tape is being pulled ahead
by the take-up torque overpowering the capstan/pinch roller, it would be
running fast.

Regards,
Tim Schwartz
Bristol Electronics

 

[Phil Allison]

Tim Schwartz wrote:

doubt that his issue is a pinch roller no matter how badly glazed it
is as his machine is running SLOW, and it the tape is being pulled ahead
by the take-up torque overpowering the capstan/pinch roller, it would be
running fast.

** But a capstan spinning against a glazed roller will slip and hence not drive it round at full speed.

Most of my recent experience is with Roland tape echoes which use a 5 metre long loop squirming around in a box. Back tension come from pairs of felt pads the tape passes between as it leaves and enters the box.

When the roller is glazed, tape speed is slow and unsteady.

Also, tape becomes slightly sticky with age and grips to the heads as it passes over them - so much so that in some cases the loop will stop moving completely until you lift the tape off the heads and start again. This is the case even when the pinch roller in perfect condition.

The fix here is to clean all the heads and guides and replace the loop.

..... Phil

 

[Colin Horsley]

On 21/12/2014 13:11, Phil Allison wrote:

Mike wrote:
Phil Allison wrote:
:

Phil Allison wrote:

Since no new supply of suitable rollers exists, I fit the old one
with a suitable shaft and lock it into the chuck of a bench drill
spinning at 600rpm - then, using finger pressure on a piece of fine
sand paper wrapped around strip of wood, gently remove the shiny
surface & restore the needed matt one.

But why does it matter? The pinch roller does not need friction to the
tape.

** It absolutely does.

The simple explanation is in the words you snipped.


It is the capstan that needs that.

** The capstan has no grip to the tape - since polished steel and
smooth tape have no mutual friction.

I can see you might need some resilience so that the tape is not nipped
too tightly and thus reduce the contact pressure, but that's not really
a surface attribute.

** A shiny surfaced roller has no grip to the capstan.

Why the heck do you think pinch rollers ( along with idler tyres and
drive belts) are made from soft rubber in the first place ?

You ever serviced a tape recorder in your life ?

No need to be rude!


** Nothing rude about what I posted.

You clearly have no idea how a capstan tape drive works.


I said why I thought the pinch roller needed to be resilient; just a
matter of physics and pinch pressure.

** Makes no sense.

But now I see that you are relying
on an unstated but reasonable assumption: that the pinch roller is wider
than the tape so gets driven by the capstan on its margins and drives the
tape between those margins.


** Whaaaaattt - so you have never seen a capstan drive tape machine ?

Yet you still decided to argue with me about my clearly written, totally correct post, by snipping and ignoring the bits you completely misunderstood.


You could, of course, have explained that instead of ranting...


** The one rating is YOU - pal.

FFS - YOU could have admitted that YOU had no idea how a capstan tape dive worked instead of making guesses and bullshitting.

FYI:

The pinch roller is CRUCIAL to the operation - it traps the tape against the capstan shaft and resists tensions coming from the supply and take up reels. The roller's height is about twice the width of the tape so it contacts the capstan directly and is driven around by it.

The pinch roller is generally mounted on a spring loaded arm, which is held back opening a small gap unless the machine is in play or record mode. When in play or record mode, the spring loaded arm is released and holds the pinch roller firmly against the capstan trapping the tape in between.

The roller must have a flat surface, with a good amount of grip to the capstan shaft when engaged. It must also grip the tape and the shaft it turns on must be exactly parallel with the capstan itself.

A worn or old pinch roller typically has a "glazed" surface that has almost no grip to the capstan or tape - or else it may become barrel shaped. A barrel shaped roller skews the tape up or down the capstan, causing the tape to spill or wind around the roller.

With a cassette deck or VCR, the capstan drive mechanism is hidden from the operator - but with a reel to reel recorder or tape echo it is highly visible cos the tape must be manually threaded through the capstan gate.

As Pete Townshend famously said " .. the simple thing you see are all complicated ... "

Capice ?


.... Phil

Excellent description Phil.

Thank you

Col

---
This email has been checked for viruses by Avast antivirus software.
http://www.avast.com

 

[Arfa Daily]

"Gareth Magennis" <sound.service@btconnect.com> wrote in message
news:xcqdndpBw4IXoQnJnZ2dnUVZ7qqdnZ2d@bt.com...

"Phil Allison" <pallison49@gmail.com> wrote in message
news:ceb575a3-eda7-4259-9990-6306edd84c25@googlegroups.com...
Sjouke Burry wrote:



Maybe a silly suggestion, but check your scope 1khz signal.
Because those are not very reliable signal sources, specially
in old scopes. The square wave is usually oke, but the frequency
might be off. Maybe your voltmeter has a frequency measurement range.


** That might be the case OR the capstan roller has gone smooth and hard
with age and is failing to control the speed of the tape through the
capstan gate.

With this sort of defect, tape speed can increase or decrease, depending
whether the take up reel or supply reel has more torque. A simple test is
to see if it is easy to pull tape through the capstan gate with the
machine turned off - if it is, you have a problem.

Having serviced many Roland tape echo machines made back in the 1980s (the
famous Space Echo and Chorus Echo models ) I can say the one fault common
to practically ALL examples seen is a shiny, smooth pinch roller.

Since no new supply of suitable rollers exists, I fit the old one with a
suitable shaft and lock it into the chuck of a bench drill spinning at
600rpm - then, using finger pressure on a piece of fine sand paper wrapped
around strip of wood, gently remove the shiny surface & restore the needed
matt one.


... Phil



This stuff is really good on pinch rollers.
http://www.amazon.co.uk/AF-International-Platen-Cleaner-Restorer/dp/B0012IKSHO/ref=sr_1_1?ie=UTF8&qid=1419000776&sr=8-1&keywords=platenclene

Oh you little darlin' Gareth ! This was one of my favourite workshop
chemicals. I had one and it lasted years and years. When it ran out, I
really mourned as I was unable to find it still for sale anywhere. As soon
as Crimbo is out of the way, I will be ordering a can !

Arfa

Gareth.

 

[Arfa Daily]

"Sofa Slug" <sofaslug@invalid.invalid> wrote in message
news:m6ssvi$ifg$1@dont-email.me...

On 12/17/2014 10:18 AM, captainvideoxxxx@gmail.com wrote:

The OEM flat belt though was very tired and had "assumed the
position"
of an oval from sitting in one position unused for so long. I
couldn't find anything around here having that circumference that was
2.0 mm thick so as a temporary measure I substituted a much thinner
belt. There is a very slight amount of wow which can be seen when
looking at the capstan flywheel with the strobe using this substitute
belt, and I'm guessing that it could be stretching back and forth
ever so slightly as it spins, but you really don't notice it on music
and it's only temporary until I can find something a little more
appropriate. I wouldn't think that a thinner belt would contribute to
a speed error, or am I wrong in making that assumption? Lenny

I would put the correct belt on there before getting into other minutia,
otherwise you may just end up chasing your tail.

Seconded. I have had many Aiwas that use a single motor dual cassette deck
come through my workshop over the years, that have had the main drive belts
replaced with two of dissimilar thicknesses. One might be a 1 mm square
section and the other 1.2 mm. When this is the case, it is impossible to get
both decks running at the same speed, even though it is a single motor
driving both. When two belts of the same thickness are fitted speed on both
decks is identical.

Arfa

 

[Michael A. Terrell]

Arfa Daily wrote:

"Gareth Magennis" wrote:

This stuff is really good on pinch rollers.
http://www.amazon.co.uk/AF-International-Platen-Cleaner-Restorer/dp/B0012IKSHO/ref=sr_1_1?ie=UTF8&qid=1419000776&sr=8-1&keywords=platenclene

Oh you little darlin' Gareth ! This was one of my favourite workshop
chemicals. I had one and it lasted years and years. When it ran out, I
really mourned as I was unable to find it still for sale anywhere. As soon
as Crimbo is out of the way, I will be ordering a can !

I took a quart glass bottle to a local print shop and they filled it
with platen cleaner for $10. They buy it in 55 gallon drums. Smaller
shops buy it in five gallon cans.
--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

 

[Michael A. Terrell]

Tim Schwartz wrote:

Good morning,

While I realized that the model is a F4460, is the machine what they
also call an F-44? The last 2 digits might just tell you what speeds or
cabinet the machine came in, or if it was 1/4 or 1/2 track.

Anyway, if it is an F44 (Fineline 44?) I have a recollection of what
Ampex techs call a "Dropped capstan flywheel" This is where the large
cast flywheel dropped down on the capstan shaft be cause the press fit
wasn't tight enough. I think you can check this by taking the top panel
off the unit so you can really see the flywheel, and just try pulling up
on it. If that's the case then you can take the whole thing out of the
machine, clean the capstan shaft and flywheel from grease, and refit the
flywheel with some epoxy so it stays where it it supposed to.

If this is an F44, contact me off-group. I might have a manual for the
thing somewhere in the archives.

I saw a lot of loose flywheels on cheap 8-track tape decks around
1970. We would pull the capstan and flywheel, then use a small center
punch and hammer to put four equally spaced dents near the capstan, on
the bottom side of the flywheel.


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

 

[dave]

On 12/19/2014 01:58 PM, Phil Allison wrote:

Mike wrote:

Phil Allison wrote:

Since no new supply of suitable rollers exists, I fit the old one with a
suitable shaft and lock it into the chuck of a bench drill spinning at
600rpm - then, using finger pressure on a piece of fine sand paper
wrapped around strip of wood, gently remove the shiny surface & restore
the needed matt one.

But why does it matter? The pinch roller does not need friction to the
tape.

** It absolutely does.

The simple explanation is in the words you snipped.


It is the capstan that needs that.

** The capstan has no grip to the tape - since polished steel and smooth tape have no mutual friction.

I can see you might need some
resilience so that the tape is not nipped too tightly and thus reduce the
contact pressure, but that's not really a surface attribute.

** A shiny surfaced roller has no grip to the capstan.

Why the heck do you think pinch rollers ( along with idler tyres and drive belts) are made from soft rubber in the first place ?

You ever serviced a tape recorder in your life ?


.... Phil

It's the lack of pliabililty. They call it a pinch roller because it
pinches the tape. A hard rubber puck is useless. The exact dimension
isn't critical as long as the bearings fit and the plunger goes far enough.

 

[Phil Allison]

dave wrote:

Phil Allison wrote:

Since no new supply of suitable rollers exists, I fit the old one with a
suitable shaft and lock it into the chuck of a bench drill spinning at
600rpm - then, using finger pressure on a piece of fine sand paper
wrapped around strip of wood, gently remove the shiny surface & restore
the needed matt one.


It's the lack of pliabililty. They call it a pinch roller because it
pinches the tape. A hard rubber puck is useless. The exact dimension
isn't critical as long as the bearings fit and the plunger goes far enough.

** You must be thinking of pinch rollers used in VCRs which often have an internal ball race.

The vast majority RR and echo machine rollers simply have a plain bearing running on a shaft of about 4 or 5mm dia.

All the Roland 1/4 inch tape echos have a roller that is 12mm x 28mm running on a 6mm shaft.


..... Phil

 

[dave]

On 01/03/2015 04:10 PM, Phil Allison wrote:

dave wrote:

Phil Allison wrote:

Since no new supply of suitable rollers exists, I fit the old one with a
suitable shaft and lock it into the chuck of a bench drill spinning at
600rpm - then, using finger pressure on a piece of fine sand paper
wrapped around strip of wood, gently remove the shiny surface & restore
the needed matt one.


It's the lack of pliabililty. They call it a pinch roller because it
pinches the tape. A hard rubber puck is useless. The exact dimension
isn't critical as long as the bearings fit and the plunger goes far enough.


** You must be thinking of pinch rollers used in VCRs which often have an internal ball race.

The vast majority RR and echo machine rollers simply have a plain bearing running on a shaft of about 4 or 5mm dia.

All the Roland 1/4 inch tape echos have a roller that is 12mm x 28mm running on a 6mm shaft.

The rotating capstan controls the speed, the roller makes sure the tape
doesn't slip. There used to be a couple high end machines without pinch
rollers from Japan.

I spent many years fixing Ampex 600, 300, 351, 440, PR10; Otari MX5050;
ATC, Spartamatic, ITC cart machines. If the reel tension is right the
roller barely does anything.

I love when you turn the Space Echoes up too high and they make their
own music.