- Ampex F4460 reel to reel. - 11 Updates
| captainvideo462009@gmail.com: Dec 18 07:16PM -0800 > 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 |
| jurb6006@gmail.com: Dec 18 10:32PM -0800 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 |
| jurb6006@gmail.com: Dec 18 10:37PM -0800 >"It is usual to have that much ..." Of course I meaant unusual but forgot the un part. Have an uncola. |
| Sjouke Burry <burrynulnulfour@ppllaanneett.nnll>: Dec 19 07:45AM +0100 > 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 <pallison49@gmail.com>: Dec 19 01:22AM -0800 Sjouke Burry wrote: > 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 |
| "Mark Zacharias" <mark_zacharias@labolgcbs.net>: Dec 19 04:04AM -0600 "Sjouke Burry" <burrynulnulfour@ppllaanneett.nnll> wrote in message news:5493c99f$0$28003$703f8584@textnews.kpn.nl... > 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. |
| Phil Allison <pallison49@gmail.com>: Dec 19 03:39AM -0800 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 |
| Tim Schwartz <tim@bristolnj.com>: Dec 19 07:39AM -0500 > 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" <sound.service@btconnect.com>: Dec 19 02:56PM "Phil Allison" <pallison49@gmail.com> wrote in message news:ceb575a3-eda7-4259-9990-6306edd84c25@googlegroups.com... Sjouke Burry wrote: > 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 <news@mjcoon.plus.com>: Dec 19 09:24AM -0600 On Fri, 19 Dec 2014 14:56:02 +0000, Gareth Magennis wrote: > 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" <sound.service@btconnect.com>: Dec 19 03:53PM "Mike" <news@mjcoon.plus.com> wrote in message news:T6qdnd5SDoGz3gnJnZ2dnUVZ8oadnZ2d@brightview.co.uk... > 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. |
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