AV repairs
captainvi...@yahoo.com
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
Franc Zabkar
<captainvi...@yahoo.com> put finger to keyboard and composed:
>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.?
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
--
Please remove one 'i' from my address when replying by email.
Matti Adolfsen
> 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
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
captainvi...@yahoo.com
wrote:
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
bz
news:1173389826.1...@n33g2000cwc.googlegroups.com:
I don't suppose your powerline frequency is running at 57.333 Hz, but that
would do it.
--
bz 73 de N5BZ k
please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.
bz+...@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap
Jerry Peters
slightly slower than 1800 rpm. How much slower depends upon the actual
motor design.
Jerry
Franc Zabkar
<captainvi...@yahoo.com> put finger to keyboard and composed:
>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
Induction motors need "slip" to operate properly. A figure of 5% or
less is typical.
http://www.electricmotors.machinedesign.com/guiEdits/Content/bdeee11/bdeee11_7.aspx
"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."
Homer J Simpson
<captainvi...@yahoo.com> wrote in message
news:1173389826.1...@n33g2000cwc.googlegroups.com...
> 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?
Yes
> Varying the line voltage around 120V has very little effect on speed
> so it appears that it is running synchronously.
No.
> There is no capacitor
> externally or internally. I just can't imagine what could have
> possibly failed (if something did), to cause this. Lenny
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
captainvi...@yahoo.com
> <captainvideo462...@yahoo.com> wrote in message
no there doesn't seem to be any reason for this . Lenny