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The machine will start very slow. There is only one motor on this machine. Initially there is very little torque and low speed. After about 30 seconds or so the speed and torque increase however it never reaches full speed. The tape runs slow. I have lubricated it and there doesn't seem to be excessive play in the bearings nor is it binding. Does anyone know what would cause an AC motor such as this to exhibit these symptoms? This motor was used in an old Ampex audio tape recorder manufactured in the late 1950's. I'm in desperate need of a replacement or repair information for this motor. The label reads: Howard Industries Inc. Festus Missouri Loyd scruggs Div.

115V 60cy. Model: 28125-2903 .7A 55W Code 1061 Does anyone have any information on it such as RPM.? By chance, does anyone know who can possibly supply this part? Any information would be most sincerely appreciated. Thanks. Lenny Stein, CET. Barlen Electronics. 465 Derry Road Chester, N.H. 03036
Reply to
captainvideo462002
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On 6 Mar 2007 17:08:40 -0800, " snipped-for-privacy@yahoo.com" put finger to keyboard and composed:

I'd suggest you use a micrometer to measure the diameter of the capstan shaft and then calculate the flywheel RPM by dividing the tape speed by the shaft circumference.

Then calculate the motor RPM as follows:

motor RPM = capstan RPM x (flywheel diameter)/(motor pulley diameter)

- Franc Zabkar

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Reply to
Franc Zabkar

is this a synchronous motor with capacitor? at 60 Hz, a 4 pole motor gives you 1800 RPM, 6 pole motor gives 1200. A common failure is a blown capacitor, resulting weak torque and starting problems.

Sometimes they used capacitors with PCB. be careful, this is poisonous.

Hope this helps Matti Adolfsen Kemi Finland

Reply to
Matti Adolfsen

I disassembled the motor cleaned it and lubricated it with ATF. It appears to be in very good condition. There is no end play in the bushings and very little apparent wear. It starts better now and comes right up to full speed, however the speed is 1720RPM either loaded or running free. Same as before the cleaning. There seems to be four poles which would suggest 1800RPM as you mentioned. Is it theoretically possible for a four pole motor to operate at 1720RPM? Varying the line voltage around 120V has very little effect on speed so it appears that it is running synchronously. There is no capacitor externally or internally. I just can't imagine what could have possibly failed (if something did), to cause this. Lenny

Reply to
captainvideo462002

" snipped-for-privacy@yahoo.com" wrote in news: snipped-for-privacy@n33g2000cwc.googlegroups.com:

I don't suppose your powerline frequency is running at 57.333 Hz, but that would do it.

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bz    	73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an 
infinite set.

bz+ser@ch100-5.chem.lsu.edu   remove ch100-5 to avoid spam trap
Reply to
bz

If it's not really a synchronous motor, it's normal for it to run slightly slower than 1800 rpm. How much slower depends upon the actual motor design.

Jerry

Reply to
Jerry Peters

On 8 Mar 2007 13:37:06 -0800, " snipped-for-privacy@yahoo.com" put finger to keyboard and composed:

Induction motors need "slip" to operate properly. A figure of 5% or less is typical.

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"Synchronous speed is the absolute upper limit of motor speed. At synchronous speed, there is no difference between rotor speed and rotating field speed, so no voltage is induced in the rotor bars, hence no torque is developed. Therefore, when running, the rotor must rotate slower than the magnetic field. The rotor speed is just slow enough to cause the proper amount of rotor current to flow, so that the resulting torque is sufficient to overcome windage and friction losses, and drive the load. This speed difference between the rotor and magnetic field, called slip, is normally referred to as a percentage of synchronous speed."

- Franc Zabkar

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Please remove one 'i' from my address when replying by email.
Reply to
Franc Zabkar

Yes

No.

You'd have to pull it apart to see, but it is possible that the rotor bars have melted the solder. I doubt it though.

IME, it is the bearings. I would try to strip the oil with a solvent, check for ANY play, and relubricate with Oilite lubricant.

Oilite: oil impregnated bronze bearings

Reply to
Homer J Simpson

no there doesn't seem to be any reason for this . Lenny

Reply to
captainvideo462002

Then I'd consider all electrical problems, low voltage, shorted turn, defective rotor or stator.

Reply to
Homer J Simpson

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