Ampex F4460 reel to reel.

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

 

[N_Cook]

On 17/12/2014 05:53, 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

What gives the speed change? conical/stepped jockey assembly out of
registration?

 

[N_Cook]

Perhaps a tyre cracked and fallen off , but running against the pulley
itself now.

 

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

Well I'm afraid that I misstated something. The Strobotac was actually aimed at the motor pulley, not the capstan. The speed reading that I got of 1795 RPM was in fact the motor pulley speed. The capstan of course would be spinning much slower.

So William, you mentioned 3 percent. I'm assuming that's 3 percent of 1850? Are you thinking that if I could bring my speed up 3 percent my sine wave would in fact then occupy a 1.0ms. period? And how would you increase the speed of a synchronous motor? Lenny

 

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

To answer your questions Mike yes there is a flat belt from motor pulley to capstan flywheel, (see further explanation on that below). The load test on the motor was putting a drag on it with my finger as it was turning. It had no trouble maintaining speed as observed with the strobe tach. i don't understand what you mean when you ask if the capstan has to turn the "full spool". As far as helping manually there really is no way to help manually other than by decreasing the hold back tension. I tried that too but it didn't make much difference. What follows is some further information.

One other thing that I didn't mention was the the main drive belt. It is a flat belt which is roughly 2.0mm thick and has a circumference of approximately 35cm. The other belts are basically just different sized O rings which only needed the slick stripped off of them to expose some good grippy rubber. I had to do that with the capstan pinch roller as well. I used a bit of lacquer thinner on the belts and sand paper and thinner on the roller too to get to some good rubber

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

 

[William Sommerwerck]

The motor is running 3% slow, not 25%. So the problem has to be somewhere
between the motor and the capstan.

 

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

I'm thinking along those lines too but do you think that 55RPM slow would cause such a drastic slowdown on playback? Here is another interesting observation. I have a another similar Ampex junker in the shop. It is a different model but a similar chassis. The motor is a 2 wire job from a different contractor and apparently with no external capacitor. The motor pulley, capstan, flywheel, etc all look the same. I had considered trying to swap motors but decided to do a speed test on the other one first. It spins up at 1680 RPM. So either there are different sized parts in that chassis, or that motor is bad too. Lenny

 

[Mike]

On Wed, 17 Dec 2014 08:46:01 -0800, captainvideo462009 wrote:

Well I'm afraid that I misstated something. The Strobotac was actually
aimed at the motor pulley, not the capstan. The speed reading that I got
of 1795 RPM was in fact the motor pulley speed. The capstan of course
would be spinning much slower.

So William, you mentioned 3 percent. I'm assuming that's 3 percent of
1850? Are you thinking that if I could bring my speed up 3 percent my
sine wave would in fact then occupy a 1.0ms. period? And how would you
increase the speed of a synchronous motor? Lenny

I don't remember working on reel-to-reel decks. But have a couple of
thoughts. Is this a (clean?) belt drive between motor and capstan? Was the
"load" test with the motor or capstan being braked? Does the capstan have
to turn the full spool and does it rotate freely? Does helping manually
make any difference?

Mike.

 

[chuck]

On Wed, 17 Dec 2014 10:18:41 -0800 (PST), 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

To answer your questions Mike yes there is a flat belt from motor pulley to capstan flywheel, (see further explanation on that below). The load test on the motor was putting a drag on it with my finger as it was turning. It had no trouble maintaining speed as observed with the strobe tach. i don't understand what you mean when you ask if the capstan has to turn the "full spool". As far as helping manually there really is no way to help manually other than by decreasing the hold back tension. I tried that too but it didn't make much difference. What follows is some further information.

One other thing that I didn't mention was the the main drive belt. It is a flat belt which is roughly 2.0mm thick and has a circumference of approximately 35cm. The other belts are basically just different sized O rings which only needed the slick stripped off of them to expose some good grippy rubber. I had to do that with the capstan pinch roller as well. I used a bit of lacquer thinner on the belts and sand paper and thinner on the roller too to get to some good rubber

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

Lenny,

About 12 years ago I had a Crown R to R that would not play tapes at
the correct speed and it turned out to be the motor. I had lubed the
bearings and there was very little rotational resistance but still the
speed was incorrect. I got a rebuilt motor from a former Crown
employee and the speed was spot on. I never found out what caused the
problem. Chuck

 

[Sofa Slug]

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.

 

[Bruce Esquibel]

captainvideo462009@gmail.com wrote:


> If anyone has any thoughts on this I'd sure appreciate hearing them.

I have one stupid idea, is there a switch somewhere on the rear panel for
changing the line cycles from 50hz to 60hz?

I remember some older Akai decks (1710/20/30 come to mind) has this along
with a mechanical voltage selector for the unit, from 100vac to 220.

I just seem to remember if the 50/60hz switch was wrong, there was a speed
problem with the capstan motor, although I think it was along the lines of
running fast (switch on 50hz when you are feeding in 120v/60hz).

There is a fairly large ratio on the capstan, figuring the diameter that
goes against the pinch roller is 1/4" or less and the flywheel part was 5
or 6 inches (at least), it's like 25:1 or 30:1.

Everything seems to point to the belt, because that usually is all that is
there between the motor and flywheel but I've see broken belts, belts with
flat spots, belts that turned into glue but none of them from memory that
would cause a constant 25% loss of rpm. No rotation or really bad wow and
flutter.

I'm guessing if it'a "universal hysteresis" motor and the machine was
designed for 100v to 220v without adapters, it's in the voltage or cycle
selection somehow.

It might even be a mechanical adjustment. Just occured to me the earlier
AKAI units had like a screw driver slot to change the motor speed via tossing
it on a different pully off the motor. The hole was marked 50/60hz.

If the shaft has a dual pulley, might just be on the wrong one.

-bruce
bje@ripco.com

 

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

Those are some great ideas Bruce but I think I've been down that whole road already. The machine is definitely from the US market only, that is 115V 60 cyc marked. Yesterday I tried putting a small AC cap in parallel with the original 3uf cap. It made the motor hum and slowed it down. Today I'll try decreasing the capacitance slightly and see what happens. I'm running out of tricks though. I still have to wonder though would a 55RPM drop in motor speed cause the degree of speed problem I'm seeing on the tape? Lenny

 

Well that clears up a couple questions I was going to ask. If you are our Lenny, I thought you were in the US but really never knew it for sure. Never gave it a thought.

However, looking at the responses I see a few things. for one, the 50/60 Hz sitch or whatver, if wrong would make it run fast. Having worked on this kind of shit I say the following :

First, when you measure the RPM of the motor, is that with the belts etc. disconnected ?

With everything disconnected, does the shaft turn freely ? If you just give it a flick it should keep turning from its own momentum.

Same is true of the flywheel and capstan.

Belts typically lose a few RPM here and there, alost always. that is why there are TEETH on the timing belt in cars. Of course teeth here would cause flutter. Capstan bearings can get sticky. What's more alot of them wear out and then the capstan is not held at the correct angle. If you have a bearing problem I could actusally make one if I can get the brass stock, but there is a workaround. the bearing is usually screwed to the main chassis2 by three screws. Most of the tiome you can rotate the bearing and the capastan will align because all the pressure is against fresh parts of the surface. Of course it is possible that this has already been done if you are not the original purchaser.

So get everything disconnected and turn things freehand. Also, with the belt off, engage the pinch roller. It should not cause all that much drag. If so, you might have a groove worn into the capstan bearing.

Actually I should call it a bushing, they are usually brass. I have never seen one with ball bearings.

Sometimes you can tell if the bushings are worn by the behavior of the tape as it goes through. you, I think you would have noticed that but it can also be insidious. It all depends on the architecture of the machine. there is a force applied by the pinch roller, and there is a force applied by the belt or idler. These cause a certain wear pattern. This varies of course because of whatever angle the belt or pulley comes from, but of course the force from the pinch roller is always perpendicular to the tape path, or close.

If you don't figure this out soon I will see if maybe hifiengine has rthe manual for it and give it a look. It sounds like you will figure it out but you need to get back to basic mechanics.

Incidentally, I THINK (not totally sure) that if the cap starts going bad on a cap run motor it will still turn about the same RPMs but pull more current. that fact that irt is a little low means maybe the cap is really bad and the load is pulling it out of synchronicity. So it matters if you check it under load or not, and actually to see if there is a major difference.

We had a discussion about that on one of the sci dot whatevers a couple years ago about replacing the capacitors in people's central AC units, that is could save them money. Years ago my Mother's house was hot in the summer because it was so damn expensive to run the air. Then it quit completely. Atr I threw in a run cap it was alot cheaper to run. But the thing is that it seems like these things just run at the right RPMs until theyu do not run at all, IN THAT APPLICATION.

Friggin R2Rs, why the cap ? And change the cap for 50 Hz and all that shit. why didn't thwey just use a brushless slotless DC motor ?

Oh yeah. Oldness. I can feel it.

 

[William Sommerwerck]

wrote in message news:9a5b307e-8fa0-467b-94b7-9085087d673d@googlegroups.com...

Those are some great ideas Bruce but I think I've been down that whole road
already. The machine is definitely from the US market only, that is 115V
60Hz
marked. Yesterday I tried putting a small AC cap in parallel with the
original
3uf cap. It made the motor hum and slowed it down. Today I'll try decreasing
the capacitance slightly and see what happens. I'm running out of tricks
though.
I still have to wonder though would a 55RPM drop in motor speed cause the
degree of speed problem I'm seeing on the tape? Lenny

As I pointed out, it's a 3% change. Gears and pulleys work on ratios, not
absolute values. The motor appears to be basically "on speed", so the problem
has to be somewhere else.

This is not a personal remark, just a statement of what I see as fact. It
appears that you don't understand much about mechanical systems. You need to
find someone who feels comfortable with them, and have him take a look,

 

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

 

Fuck Lenny I am way cooler than you, or was...

I had me a Viking Of Mineapolis. It was not only tube, the optional record amplifiers could be removed, unplugged. Whether yuo bought into the record capability was irrelevant however, to the playback. All you needee was a preamp the had tape (NARTB equalized) inputs. Just so happens I had one, and for the life of me I can't reme,mber the make and model of it. It MAYT have been an H.H. Scott but don't take that to the usury.... er .. bank.

Anyway, to get back to your dilemma. At this point I suspect your tachometer. That ia not a large error. Hoever this does not explain the much larger error in the actual tape speed.

Here is something interesting just occurred to me, you know tape does not shrink. Is it possible that the slight error in motor speed combined with the tape being stretched has resulted in the cumulative error you obseved ?

Really, 700 some Hz is way off of 1,000. You can REALLY hear that. You said it sounded slow, I guess it was. But why.

Ihave fucked with a couple of reel to reels laely and I see the tape is not what it once was, n fact me and my little crew have zero good tape. The best shit we got right now clogs up theheadss in like, half hour or something.. It still plays but the level keeps dropping. I looked at the prices of new tape and decided, not.

These are really cool. When I hit the lottery I will send a minion to pick me one up... I have digital solution anyway, but I still think they're cool.. In fact my buddy has a nice Teac he is probaably going to sell. I worked on it, it is a fucink nice deck, really. Takes the 10" reels. Four track simulcord. Though it is a three head, it can switch the playback head to the record head in sound on sound to keep the sound in sync. Otherwise yoy owuld have to waste a generation on every overdub. Or whatever. Ask Les Paul lol. you know whatI mean. The thing is a practical recording studio.

I oculd not get nfo on your Ampex from the usual sources. I did however score in the 99th percentile in mechanical reasoning in one of them thar pre SAT typee thingies when I was young. I mean before I crashed a car young, and that means young. All those idlers and shit, unless ther eis a driven shaft rubber wheel (whiich is not an idler) or some type of stepped thing, the size does not really matter.

An idler by definition is not driven by its shaft. If it is, it is a drive wheel, not an idler.

For example, on a record player if you were to make the idler wheel a bit bigger, the speed would not change except for maybe what the rubber drags it down or something. Ther math has not changed because the only numbers tha tmatter are those of the SFM of the motor shaft and the SFM of the driven flywheel which is either the tunrtable or the alumin(i)um thing attched to the capstan. Math it math.

It is usual to have that much of a speed error on something like that, but of course that explins your presence here...

Anyway, the way I see it is suspect the RPM meter about the motor, OR maybe those extra wires go to the cap to trim the speed. (???) Now that would be tripped out. But tell you what, it is very possible.

Look see if there is any rubber in that thing that is nailed down. By that I mean a driven shaft with a rubber surface driving something. There is a good reason they stuck with the metal motor shaft and the final dirven thing, those two diaameters make the ratio and that is that. Other designs not so much.

hell, you might have to rewire the capacitor to give more RPMs. Seriously, that is possible.

Wish ?I oculd get a mmanual ion that thing, dammit

 

>"It is usual to have that much ..."

Of course I meaant unusual but forgot the un part.

Have an uncola.

 

[Sjouke Burry]

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.

 

[Phil Allison]

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

 

[Phil Allison]

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.


..... Phil