3 Sep
2014
3 Sep
'14
6:16 a.m.
I'm refurbishing a TU56 and of course the tape drive motor capacitors are completely
shot. They're 100uF and only need to be about 60-80V to be quite safe (originals
100uF/55V) but I can only find capacitors rated for 450V which is no big issue except for
their size.
I'm thinking of using motor start capacitors. They're only rated intermittent but
I feel that the derating to around 60V should probably give them a good lifetime. Views?
Bob
9:47 a.m.
100uF/100V or 63V aren't especially rare.
Those are just normal value's or are they bipolar types?
-Rik
-----Oorspronkelijk bericht-----
Van: "Robert Adamson" <bob at theadamsons.co.uk>
Verzonden: ?3-?9-?2014 16:34
Aan: "cctech at classiccmp.org" <cctech at classiccmp.org>
Onderwerp: TU56 Motor Run Capacitors.
I'm refurbishing a TU56 and of course the tape drive motor capacitors are completely
shot. They're 100uF and only need to be about 60-80V to be quite safe (originals
100uF/55V) but I can only find capacitors rated for 450V which is no big issue except for
their size.
I'm thinking of using motor start capacitors. They're only rated intermittent but
I feel that the derating to around 60V should probably give them a good lifetime. Views?
Bob
10:29 a.m.
I believe they're plain capacitors; bipolar, non-electrolytic. Those
are a bit more difficult to find.
On Wed, Sep 3, 2014 at 7:47 PM, Rik Bos <hp-fix at xs4all.nl> wrote:
100uF/100V or 63V aren't especially rare.
Those are just normal value's or are they bipolar types?
-Rik
-----Oorspronkelijk bericht-----
Van: "Robert Adamson" <bob at theadamsons.co.uk>
Verzonden: ?3-?9-?2014 16:34
Aan: "cctech at classiccmp.org" <cctech at classiccmp.org>
Onderwerp: TU56 Motor Run Capacitors.
I'm refurbishing a TU56 and of course the tape drive motor capacitors are completely
shot. They're 100uF and only need to be about 60-80V to be quite safe (originals
100uF/55V) but I can only find capacitors rated for 450V which is no big issue except for
their size.
I'm thinking of using motor start capacitors. They're only rated intermittent but
I feel that the derating to around 60V should probably give them a good lifetime. Views?
Bob
10:32 a.m.
And of course, Wikipedia can be helpful:
(from http://en.wikipedia.org/wiki/Motor_capacitor)
Run capacitors
Some single-phase AC electric motors require a "run capacitor" to
energize the second-phase winding (auxiliary coil) to create a
rotating magnetic field while the motor is running.[3]
Run capacitors are designed for continuous duty while the motor is
powered, which is why electrolytic capacitors are avoided, and
low-loss polymer capacitors are used instead. Run capacitors are
mostly polypropylene film capacitors and are designed for continuous
duty, and they are energized the entire time the motor is running.[1]
Run capacitors are rated in a range of 1.5 to 100 microfarads (?F or
mfd), with voltage classifications of 370 V or 440 V.[1]
If a wrong capacitance value is installed, it will cause an uneven
magnetic field which causes the rotor to hesistate at those spots that
are uneven, which can be observed as uneven motor rotation speed,
especially under load. This hesitation can cause the motor to become
noisy, increase energy consumption, cause performance to drop, and
cause the motor to overheat.[3]
On Wed, Sep 3, 2014 at 8:29 PM, Camiel Vanderhoeven <iamcamiel at gmail.com> wrote:
I believe they're plain capacitors; bipolar,
non-electrolytic. Those
are a bit more difficult to find.
On Wed, Sep 3, 2014 at 7:47 PM, Rik Bos <hp-fix at xs4all.nl> wrote:
> 100uF/100V or 63V aren't especially rare.
> Those are just normal value's or are they bipolar types?
>
> -Rik
>
> -----Oorspronkelijk bericht-----
> Van: "Robert Adamson" <bob at theadamsons.co.uk>
> Verzonden: ?3-?9-?2014 16:34
> Aan: "cctech at classiccmp.org" <cctech at classiccmp.org>
> Onderwerp: TU56 Motor Run Capacitors.
>
> I'm refurbishing a TU56 and of course the tape drive motor capacitors are
completely shot. They're 100uF and only need to be about 60-80V to be quite safe
(originals 100uF/55V) but I can only find capacitors rated for 450V which is no big issue
except for their size.
>
> I'm thinking of using motor start capacitors. They're only rated intermittent
but I feel that the derating to around 60V should probably give them a good lifetime.
Views?
>
> Bob
11:08 a.m.
Ok an asynchronous motor, no electronics involved.
-Rik
-----Oorspronkelijk bericht-----
Van: "Camiel Vanderhoeven" <iamcamiel at gmail.com>
Verzonden: ?3-?9-?2014 20:53
Aan: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>
Onderwerp: Re: TU56 Motor Run Capacitors.
And of course, Wikipedia can be helpful:
(from http://en.wikipedia.org/wiki/Motor_capacitor)
Run capacitors
Some single-phase AC electric motors require a "run capacitor" to
energize the second-phase winding (auxiliary coil) to create a
rotating magnetic field while the motor is running.[3]
Run capacitors are designed for continuous duty while the motor is
powered, which is why electrolytic capacitors are avoided, and
low-loss polymer capacitors are used instead. Run capacitors are
mostly polypropylene film capacitors and are designed for continuous
duty, and they are energized the entire time the motor is running.[1]
Run capacitors are rated in a range of 1.5 to 100 microfarads (?F or
mfd), with voltage classifications of 370 V or 440 V.[1]
If a wrong capacitance value is installed, it will cause an uneven
magnetic field which causes the rotor to hesistate at those spots that
are uneven, which can be observed as uneven motor rotation speed,
especially under load. This hesitation can cause the motor to become
noisy, increase energy consumption, cause performance to drop, and
cause the motor to overheat.[3]
On Wed, Sep 3, 2014 at 8:29 PM, Camiel Vanderhoeven <iamcamiel at gmail.com> wrote:
I believe they're plain capacitors; bipolar,
non-electrolytic. Those
are a bit more difficult to find.
On Wed, Sep 3, 2014 at 7:47 PM, Rik Bos <hp-fix at xs4all.nl> wrote:
> 100uF/100V or 63V aren't especially rare.
> Those are just normal value's or are they bipolar types?
>
> -Rik
>
> -----Oorspronkelijk bericht-----
> Van: "Robert Adamson" <bob at theadamsons.co.uk>
> Verzonden: ?3-?9-?2014 16:34
> Aan: "cctech at classiccmp.org" <cctech at classiccmp.org>
> Onderwerp: TU56 Motor Run Capacitors.
>
> I'm refurbishing a TU56 and of course the tape drive motor capacitors are
completely shot. They're 100uF and only need to be about 60-80V to be quite safe
(originals 100uF/55V) but I can only find capacitors rated for 450V which is no big issue
except for their size.
>
> I'm thinking of using motor start capacitors. They're only rated intermittent
but I feel that the derating to around 60V should probably give them a good lifetime.
Views?
>
> Bob
11:50 a.m.
?Asynchronous??
Run caps are found in AC induction motors fed by a single phase power source, whether
electronic or not. If you have an actual multi-phase power source (3 phase mains or a
multi-phase motor controller) then there is no run cap.
paul
On Sep 3, 2014, at 3:08 PM, Rik Bos <hp-fix at xs4all.nl> wrote:
Ok an asynchronous motor, no electronics involved.
-Rik
-----Oorspronkelijk bericht-----
Van: "Camiel Vanderhoeven" <iamcamiel at gmail.com>
Verzonden: ?3-?9-?2014 20:53
Aan: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>
Onderwerp: Re: TU56 Motor Run Capacitors.
And of course, Wikipedia can be helpful:
(from http://en.wikipedia.org/wiki/Motor_capacitor)
Run capacitors
Some single-phase AC electric motors require a "run capacitor" to
energize the second-phase winding (auxiliary coil) to create a
rotating magnetic field while the motor is running.[3]
Run capacitors are designed for continuous duty while the motor is
powered, which is why electrolytic capacitors are avoided, and
low-loss polymer capacitors are used instead. Run capacitors are
mostly polypropylene film capacitors and are designed for continuous
duty, and they are energized the entire time the motor is running.[1]
Run capacitors are rated in a range of 1.5 to 100 microfarads (?F or
mfd), with voltage classifications of 370 V or 440 V.[1]
If a wrong capacitance value is installed, it will cause an uneven
magnetic field which causes the rotor to hesistate at those spots that
are uneven, which can be observed as uneven motor rotation speed,
especially under load. This hesitation can cause the motor to become
noisy, increase energy consumption, cause performance to drop, and
cause the motor to overheat.[3]
On Wed, Sep 3, 2014 at 8:29 PM, Camiel Vanderhoeven <iamcamiel at gmail.com>
wrote:
I believe they're plain capacitors; bipolar,
non-electrolytic. Those
are a bit more difficult to find.
On Wed, Sep 3, 2014 at 7:47 PM, Rik Bos <hp-fix at xs4all.nl> wrote:
> 100uF/100V or 63V aren't especially rare.
> Those are just normal value's or are they bipolar types?
>
> -Rik
>
> -----Oorspronkelijk bericht-----
> Van: "Robert Adamson" <bob at theadamsons.co.uk>
> Verzonden: ?3-?9-?2014 16:34
> Aan: "cctech at classiccmp.org" <cctech at classiccmp.org>
> Onderwerp: TU56 Motor Run Capacitors.
>
> I'm refurbishing a TU56 and of course the tape drive motor capacitors are
completely shot. They're 100uF and only need to be about 60-80V to be quite safe
(originals 100uF/55V) but I can only find capacitors rated for 450V which is no big issue
except for their size.
>
> I'm thinking of using motor start capacitors. They're only rated intermittent
but I feel that the derating to around 60V should probably give them a good lifetime.
Views?
>
> Bob
12:32 p.m.
On 09/03/2014 12:50 PM, Paul Koning wrote:
?Asynchronous??
Run caps are found in AC induction motors fed by a single phase power
source, whether electronic or not. If you have an actual multi-phase
power source (3 phase mains or a multi-phase motor controller) then
there is no run cap.
Are nonpolar electrolytics uncommon? Seems to me that one major use is
in audio crossovers for the "make it louder" crowd.
Here's a 100 uF, 100V one from All Electronics for about a buck and a half.
http://www.allelectronics.com/make-a-store/item/nc-100/100uf-100v-non-polar…
They're in most distributors' catalogs--just look for "non polar capacitor.
FWIW
Chuck
10 Sep
10 Sep
12:35 a.m.
On Wed, 3 Sep 2014, Chuck Guzis wrote:
On 09/03/2014 12:50 PM, Paul Koning wrote:
Fewer and fewer capacitor manufacturers make non-polarized electrolytics
now, just like what has happened with the ultra-low ESR types required for
certain computer motherboards. Nichicon for example has discontinued most
of their non-polarized electrolytics, except for their VP and EP radial
types. Even those are often not stocked by distributors (or if they are,
they have a very limited selection of the values Nichicon makes).
None of these small non-polarized electrolytics are suitable for motor
start/run applications though, their ripple current rating is just far to
low. I have an antenna rotator with a 24V motor that I've been completely
unable to find a replacement motor run capacitor that will fit in the
controller's cabinet. The original looks to be a wax-paper type, but it is
only rated for 50VAC. The best option I've come up with so far (not yet
installed) is a pair of high ripple current rated polarized electrolytics
back to back in series.
?Asynchronous??
Run caps are found in AC induction motors fed by a single phase power
source, whether electronic or not. If you have an actual multi-phase
power source (3 phase mains or a multi-phase motor controller) then
there is no run cap.
Are nonpolar electrolytics uncommon? Seems to me that one major use is
in audio crossovers for the "make it louder" crowd.
Here's a 100 uF, 100V one from All Electronics for about a buck and a
half.
http://www.allelectronics.com/make-a-store/item/nc-100/100uf-100v-non-polar…
They're in most distributors' catalogs--just look for "non polar
capacitor.
7:56 a.m.
On 09/10/2014 01:35 AM, Tothwolf wrote:
None of these small non-polarized electrolytics are
suitable for motor
start/run applications though, their ripple current rating is just far
to low. I have an antenna rotator with a 24V motor that I've been
completely unable to find a replacement motor run capacitor that will
fit in the controller's cabinet. The original looks to be a wax-paper
type, but it is only rated for 50VAC. The best option I've come up with
so far (not yet installed) is a pair of high ripple current rated
polarized electrolytics back to back in series.
Indeed, if one looks carefully at the nonpolar crossover caps, they
appear to be nothing more than back-to-back electrolytics. On the other
hand, I note that motor run capacitors have gotten a lot smaller over
the years, so a higher-voltage unit just might fit.
--Chuck
3 Sep
3 Sep
12:35 p.m.
Yes, mains frequency determines the rotation speed of the field. Rotor speed is a little
slower so there is current inducted in the rotor 'cage' which creates a another
field. This field is forced to follow the mains field. Because there is a little speed
difference 'slip' between the stator field and and the rotor speed. Those motors
are called asynchronous, slip is between 2-6% depending of the size of the motor and power
needed.
This goes for 1 and 3 fade machines both have rotating fields.
-Rik
-----Oorspronkelijk bericht-----
Van: "Paul Koning" <paulkoning at comcast.net>
Verzonden: ?3-?9-?2014 22:12
Aan: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>
Onderwerp: Re: TU56 Motor Run Capacitors.
?Asynchronous??
Run caps are found in AC induction motors fed by a single phase power source, whether
electronic or not. If you have an actual multi-phase power source (3 phase mains or a
multi-phase motor controller) then there is no run cap.
paul
On Sep 3, 2014, at 3:08 PM, Rik Bos <hp-fix at xs4all.nl> wrote:
Ok an asynchronous motor, no electronics involved.
-Rik
-----Oorspronkelijk bericht-----
Van: "Camiel Vanderhoeven" <iamcamiel at gmail.com>
Verzonden: ?3-?9-?2014 20:53
Aan: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>
Onderwerp: Re: TU56 Motor Run Capacitors.
And of course, Wikipedia can be helpful:
(from http://en.wikipedia.org/wiki/Motor_capacitor)
Run capacitors
Some single-phase AC electric motors require a "run capacitor" to
energize the second-phase winding (auxiliary coil) to create a
rotating magnetic field while the motor is running.[3]
Run capacitors are designed for continuous duty while the motor is
powered, which is why electrolytic capacitors are avoided, and
low-loss polymer capacitors are used instead. Run capacitors are
mostly polypropylene film capacitors and are designed for continuous
duty, and they are energized the entire time the motor is running.[1]
Run capacitors are rated in a range of 1.5 to 100 microfarads (?F or
mfd), with voltage classifications of 370 V or 440 V.[1]
If a wrong capacitance value is installed, it will cause an uneven
magnetic field which causes the rotor to hesistate at those spots that
are uneven, which can be observed as uneven motor rotation speed,
especially under load. This hesitation can cause the motor to become
noisy, increase energy consumption, cause performance to drop, and
cause the motor to overheat.[3]
On Wed, Sep 3, 2014 at 8:29 PM, Camiel Vanderhoeven <iamcamiel at gmail.com>
wrote:
I believe they're plain capacitors; bipolar,
non-electrolytic. Those
are a bit more difficult to find.
On Wed, Sep 3, 2014 at 7:47 PM, Rik Bos <hp-fix at xs4all.nl> wrote:
> 100uF/100V or 63V aren't especially rare.
> Those are just normal value's or are they bipolar types?
>
> -Rik
>
> -----Oorspronkelijk bericht-----
> Van: "Robert Adamson" <bob at theadamsons.co.uk>
> Verzonden: ?3-?9-?2014 16:34
> Aan: "cctech at classiccmp.org" <cctech at classiccmp.org>
> Onderwerp: TU56 Motor Run Capacitors.
>
> I'm refurbishing a TU56 and of course the tape drive motor capacitors are
completely shot. They're 100uF and only need to be about 60-80V to be quite safe
(originals 100uF/55V) but I can only find capacitors rated for 450V which is no big issue
except for their size.
>
> I'm thinking of using motor start capacitors. They're only rated intermittent
but I feel that the derating to around 60V should probably give them a good lifetime.
Views?
>
> Bob
1:46 p.m.
I replace all of mine with these caps I found on amazon:
http://www.amazon.com/dp/B009IMR5UO/ref=pe_385040_30332190_TE_3p_M3T1_ST1_d…
They're higher voltage and the diameter is slightly less than the originals
so they will fit without modifying the chassis. I haven't had any problems
with them (yet).
Best of all they're filled with Chinese "Vegetable oil", yum.
Marc
On Wed, Sep 3, 2014 at 1:35 PM, Rik Bos <hp-fix at xs4all.nl> wrote:
Yes, mains frequency determines the rotation speed of
the field. Rotor
speed is a little slower so there is current inducted in the rotor 'cage'
which creates a another field. This field is forced to follow the mains
field. Because there is a little speed difference 'slip' between the stator
field and and the rotor speed. Those motors are called asynchronous, slip
is between 2-6% depending of the size of the motor and power needed.
This goes for 1 and 3 fade machines both have rotating fields.
-Rik
-----Oorspronkelijk bericht-----
Van: "Paul Koning" <paulkoning at comcast.net>
Verzonden: ?3-?9-?2014 22:12
Aan: "General Discussion: On-Topic and Off-Topic Posts" <
cctalk at classiccmp.org>
Onderwerp: Re: TU56 Motor Run Capacitors.
?Asynchronous??
Run caps are found in AC induction motors fed by a single phase power
source, whether electronic or not. If you have an actual multi-phase power
source (3 phase mains or a multi-phase motor controller) then there is no
run cap.
paul
On Sep 3, 2014, at 3:08 PM, Rik Bos <hp-fix at xs4all.nl> wrote:
Ok an asynchronous motor, no electronics
involved.
-Rik
-----Oorspronkelijk bericht-----
Van: "Camiel Vanderhoeven" <iamcamiel at gmail.com>
Verzonden: ?3-?9-?2014 20:53
Aan: "General Discussion: On-Topic and Off-Topic Posts" <
cctalk at
classiccmp.org>
Onderwerp: Re: TU56 Motor Run Capacitors.
And of course, Wikipedia can be helpful:
(from http://en.wikipedia.org/wiki/Motor_capacitor)
Run capacitors
Some single-phase AC electric motors require a "run capacitor" to
energize the second-phase winding (auxiliary coil) to create a
rotating magnetic field while the motor is running.[3]
Run capacitors are designed for continuous duty while the motor is
powered, which is why electrolytic capacitors are avoided, and
low-loss polymer capacitors are used instead. Run capacitors are
mostly polypropylene film capacitors and are designed for continuous
duty, and they are energized the entire time the motor is running.[1]
Run capacitors are rated in a range of 1.5 to 100 microfarads (?F or
mfd), with voltage classifications of 370 V or 440 V.[1]
If a wrong capacitance value is installed, it will cause an uneven
magnetic field which causes the rotor to hesistate at those spots that
are uneven, which can be observed as uneven motor rotation speed,
especially under load. This hesitation can cause the motor to become
noisy, increase energy consumption, cause performance to drop, and
cause the motor to overheat.[3]
On Wed, Sep 3, 2014 at 8:29 PM, Camiel Vanderhoeven <iamcamiel at gmail.com>
wrote:
> I believe they're plain capacitors;
bipolar, non-electrolytic. Those
> are a bit more difficult to find.
>
> On Wed, Sep 3, 2014 at 7:47 PM, Rik Bos <hp-fix at xs4all.nl> wrote:
>> 100uF/100V or 63V aren't especially rare.
>> Those are just normal value's or are they bipolar types?
>>
>> -Rik
>>
>> -----Oorspronkelijk bericht-----
>> Van: "Robert Adamson" <bob at theadamsons.co.uk>
>> Verzonden: ?3-?9-?2014 16:34
>> Aan: "cctech at classiccmp.org" <cctech at classiccmp.org>
>> Onderwerp: TU56 Motor Run Capacitors.
>>
>> I'm refurbishing a TU56 and of course the tape drive motor capacitors
are completely shot. They're 100uF and only need to be about 60-80V to be
quite safe (originals 100uF/55V) but I can only find capacitors rated for
450V which is no big issue except for their size.
>>
>> I'm thinking of using motor start capacitors. They're only rated
intermittent but I feel that the derating to around 60V should probably
give them a good lifetime. Views?
>
> Bob
10:57 a.m.
Should be big ones then, and as far as I can see there's no need not to use bipolar
elco's. There shouldn't be much HF involved in a motor drive. So a little series
inductance won't be a problem.
-Rik
-----Oorspronkelijk bericht-----
Van: "Camiel Vanderhoeven" <iamcamiel at gmail.com>
Verzonden: ?3-?9-?2014 20:46
Aan: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>
Onderwerp: Re: TU56 Motor Run Capacitors.
I believe they're plain capacitors; bipolar, non-electrolytic. Those
are a bit more difficult to find.
On Wed, Sep 3, 2014 at 7:47 PM, Rik Bos <hp-fix at xs4all.nl> wrote:
100uF/100V or 63V aren't especially rare.
Those are just normal value's or are they bipolar types?
-Rik
-----Oorspronkelijk bericht-----
Van: "Robert Adamson" <bob at theadamsons.co.uk>
Verzonden: ?3-?9-?2014 16:34
Aan: "cctech at classiccmp.org" <cctech at classiccmp.org>
Onderwerp: TU56 Motor Run Capacitors.
I'm refurbishing a TU56 and of course the tape drive motor capacitors are completely
shot. They're 100uF and only need to be about 60-80V to be quite safe (originals
100uF/55V) but I can only find capacitors rated for 450V which is no big issue except for
their size.
I'm thinking of using motor start capacitors. They're only rated intermittent but
I feel that the derating to around 60V should probably give them a good lifetime. Views?
Bob
3587
days inactive
3594
days old
13 comments
9 participants
participants (9)
-
aek＠bitsavers.org -
ard＠p850ug1.demon.co.uk -
bob＠theadamsons.co.uk -
cclist＠sydex.com -
cramcram＠gmail.com -
hp-fix＠xs4all.nl -
iamcamiel＠gmail.com -
paulkoning＠comcast.net -
tothwolf＠concentric.net