Did you mean an external start capacitor?
Reducing Ampex 440 wow/flutter on playback
- Thread starter Icegoldnixon
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Brian Roth
Well-known member
Paul said:
"The Lyrec start motor is a separate coil in the same housing. It is slow and the coil often burned out."
I dunno about Paul's statement until I look again our Lyrec. As I mentioned, we may talking about different Lyrec versions.
I can say as FACT there is one...only one cap in our setup, as shown in the schemo I posted. 10 uFd as shown. No change for different running speeds. If there was an external helper motor as shown in the posted schemo, the cap isn't here (along with the motor).
Bri
Take those two hanging wires and put them in the two position terminal block. Now the start motor is connected. The start motor was never external. The start motor works on both of my motors.
Im not sure about the specifics of the Lyrec motor you mention but often the start winding has a centrifugal switch that disconnects it as soon as the motor spins up , theres a distinct click after the motor starts/or is coming to a halt. Sometimes the switch fails open , in that case the motor wont start without a helping hand , other times the switch fails closed , then the start winding burns out , which ultimately has the same effect , it wont start .
I'd heard at some point way back in time the BBC ran turntables off the 100 volt line output of a Vortexion 30/50 tube amp fed with a sine wave .
I'd heard at some point way back in time the BBC ran turntables off the 100 volt line output of a Vortexion 30/50 tube amp fed with a sine wave .
The start motor on the Lyrec is operated on Neumann lathes with a momentary action pushbutron switch mounted on the frame to the left of the turntable. After you wait forever for it to spin up to speed you spin it up by hand the next time. The motor is perfectly happy running in reverse.
For a few recordings of the Beatles, Geoff Emerick used two J37's, one chasing the other. The master had a 50Hz tone on one track, amplified and feeding the slave machine's motor. Resolving was done by hand!
Reading the bias frequency printed on the original recording sounds very clever (I like).
As others have shared for a second mechanical playback machine to finely control its playback speed fast enough to correct for both machines errors, is more than a little optimistic.
JR
I think that since the Start motor is just a separate winding it uses the same run cap. On the PG66 drawing it lists the values for different line voltage/frequency combinations. Since you use third party automation you may not have the "programmer" drawing. C11 is the run cap. It's 10uF for 117VAC/60Hz, 3uF for 220VAC/60Hz and 4uF for 220VAC/50Hz.
Those are the reel motors. The other main difference is that the capstan of the 440 is locked to the line frequency so it's impossible for it to run off speed unless the line frequency is altered. It's easy to have an Otari run off speed. I was bit in the ass doing a 1/4",1/4 track transfer on a friends MX5050 recently.
What would be the reason to choose a servo motor over a synchronous hysteresis? Varispeed?
radardoug
Well-known member
Yes, easy varispeed and synchroniser control.
SMPTE machine synchronization used speed control on the slave machine.
JR
JR
Brian Roth
Well-known member
Next time I'm at the studio, I'll definitely look at the wiring at the motor including that pair hanging in the breeze. My curiosity is piqued! <g>
In the schematic I posted in reply #28, it shows a 20 uF cap connected to what is labeled as "start motor" (which led me to believe it was an external motor). Unless that cap is hiding in the drive motor casing, it isn't in our setup. All we have here is that one 10 uF "phase" cap also as shown in the schematic in message 28.
That schemo is all I have to go by; it was given to me by Chris Muth who has come here a few times to do tweaking, tuning and repair of the lathe. I am not a "lathe guy"....this the first one I've ever been involved with after decades in the recording biz. Tape machines are more of my forte when it comes to gizmos with spinning parts <G!>.
To be honest, I never paid much attention to the Lyrec motor until it began having problems starting and running at 45 RPM. That's when I determined the ancient rotary speed select switch was crapping out, and I replaced it with a DPDT center-off toggle for selecting 45 or 33 1/3. We never cut 78.
Bri
Brian Roth
Well-known member
I asked the guys on the Ampex list, and the non-servo capstan motor on a 440 IS a hysteresis synchronous. One respondent even held his spare motor in his hands and the factory label stated that.
I THINK (a scary thought <g>) the external cap is a "phase" cap like used with the Lyrec motor.
Bri
I THINK (a scary thought <g>) the external cap is a "phase" cap like used with the Lyrec motor.
Bri
Thats fairly ingenious alright Abbey , they must have had a good amount of pre-roll to allow the eng. sync things , you could almost imagine him 'flanging' the reels to line things up just before hitting record , and maybe the odd false start and John getting cranky .
Start and run 'winding' might be the more appropriate term , typically its a bifilar arrangement on the stator ,with two different diameter wires wound together . Chief winder in the place I worked was a Latvian ex deep sea fisherman , drank like a fish , but instictively knew the coil arrangements like 'rain man' .
Start and run 'winding' might be the more appropriate term , typically its a bifilar arrangement on the stator ,with two different diameter wires wound together . Chief winder in the place I worked was a Latvian ex deep sea fisherman , drank like a fish , but instictively knew the coil arrangements like 'rain man' .
I don’t think I’ve ever seen that Lyrec schemo. To me it looks like the 20uF is external to the motor. The switches at the top are external to the motor. Now my curiosity is piqued. Maybe that cap is hiding in the frame somewhere? Rest assured no one cares if the Start motor works or will use it. There is only one run cap mounted on every motor I’ve seen.
Brian Roth
Well-known member
I'll try to remember to take some snapshots of the setup....plus check to find a label on the Lyrec. The schemo from Chris Muth seemed to trace out when I replaced the speed selector switch. With the Sax lathe, I know a lot of it was concocted and modified over the years.
I do know that since "day one" here with the lathe, the various cutting engineers always had to "spin" the platter to get it up to speed. Some moved the (now defunct) rotary switch to the "start" position while also manually goosing the platter. After doing wire tracing, that momentary "start" switch position was a placebo!
Bri
I do know that since "day one" here with the lathe, the various cutting engineers always had to "spin" the platter to get it up to speed. Some moved the (now defunct) rotary switch to the "start" position while also manually goosing the platter. After doing wire tracing, that momentary "start" switch position was a placebo!
Bri
That’s how everyone does it. My Start motor works but I never use it. It doesn’t whip it up to speed like a Technics motor. It’s faster to spin it by hand. That’s what everyone does. The motor has very little torque. That’s why it has approximately a 50kg fly wheel.
Brian Roth
Well-known member
And when the Lyrec syncs....there a wonderful small acoustical signature hmmmmmmmm in the room. <g> I'm a lathe newbie but always happy to hear that slight, LF sound from the motor when it locks into 33 or 45.
Bri
Bri
I think I know the sound you mean. Reverse polarity kind if sound. You can usually reduce it by making sure the motor is exactly level. The other thing to look out for is that the bottom of the motor isn’t touching the floor. That can cause noise.
The motor on my VMS66 needed new round foam mounts. The old ones were dried out. Finding the right sized foam has been difficult in the past. Instead of spending hours searching I decided to see if DIY was possible. After watching a couple YouTube videos I gave it a shot. The trick is to sharpen a metal tube the size you want. The rounds I needed were about 1.5” in diameter. I had a copper pipe fitting that had a 1.5” I.D. I sharpened the outside with a belt sander and the inside by hand with files. I sharpened a rube with a 1/4” O.D. for the center hole. That was this afternoon’s project. Worked great.
