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JohnH
Carpal Tunnel


Reged: 10/04/05
Posts: 1738
Loc: Squamish BC Moved!!!!!
Hurst 1/2 RPM Motor Needed
      #2524353 - 07/17/08 12:00 PM Attachment (45 downloads)

I need to replace this motor as the one on my mount no longers works due my vehicle being involved in a traffic accident.

Either the gearbox or the motor itself are cooked, I don't know. The motor isn't shorted and each pair of wires has similar resistance, but it just makes a faint buzzing noise and heats up.

The exact model number in CA and the part is a 990341.

I know some motors can be rebuilt but who to send this to?

Attachment


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Skywatchr
Carpal Tunnel


Reged: 06/03/06
Posts: 2626
Loc: North-Central Pa.
Re: Hurst 1/2 RPM Motor Needed new [Re: JohnH]
      #2524523 - 07/17/08 01:26 PM

Try here.. Hurst Motors

--------------------
18" F/5 Home-Built Dob. with Mike Dudley Mirror
6" F/15 Brass w/ D&G Lens on DS-16 Mount
DS-10 10" F/4.5 Newtonian
LXD650 and LX200 Classic Autostar Converted!
DayStar 0.45 T-Scanner with multiple ERFs
11x80 Meade, 20x80 Celestron binocs (Vintage Japan Made).
A few Naglers and 8mm and 13mm Ethos.
Gadgets and parts everywhere.


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JohnH
Carpal Tunnel


Reged: 10/04/05
Posts: 1738
Loc: Squamish BC Moved!!!!!
Re: Hurst 1/2 RPM Motor Needed new [Re: Skywatchr]
      #2524695 - 07/17/08 03:16 PM

I did try Beckwith, but they said it would be 6-7weeks right now, and I need my mount working for Table Mountain in 2 1/2 weeks.

I couldn't find any other who have it in stock.


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Skywatchr
Carpal Tunnel


Reged: 06/03/06
Posts: 2626
Loc: North-Central Pa.
Re: Hurst 1/2 RPM Motor Needed new [Re: JohnH]
      #2525141 - 07/17/08 07:39 PM

That figures! All I have is a Model DA and it's a 1 RPM.

Jeff

--------------------
18" F/5 Home-Built Dob. with Mike Dudley Mirror
6" F/15 Brass w/ D&G Lens on DS-16 Mount
DS-10 10" F/4.5 Newtonian
LXD650 and LX200 Classic Autostar Converted!
DayStar 0.45 T-Scanner with multiple ERFs
11x80 Meade, 20x80 Celestron binocs (Vintage Japan Made).
A few Naglers and 8mm and 13mm Ethos.
Gadgets and parts everywhere.


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Tom and Beth
Carpal Tunnel


Reged: 01/08/07
Posts: 2019
Loc: Tucson, AZ
Re: Hurst 1/2 RPM Motor Needed new [Re: JohnH]
      #2525337 - 07/17/08 09:19 PM

Hi John,

Did you try removing the motor to fault isolate it (run it with no load). You COULD have jammed the worm or other portion of the drive.

EDIT: This place CLAIMS to have them, call for price
http://codemicro.com/store/check_price.php?partid=1171728

Edited by Tom and Beth (07/17/08 09:24 PM)


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Skywatchr
Carpal Tunnel


Reged: 06/03/06
Posts: 2626
Loc: North-Central Pa.
Re: Hurst 1/2 RPM Motor Needed new [Re: Tom and Beth]
      #2525477 - 07/17/08 10:10 PM

When a company hides their prices, and make you contact them for a price, it usually means it's way overpriced. They want you to talk to a salesperson so they can throw a pitch at you. At least that has been my experience every time I've inquired that way. YMMV

Jeff

--------------------
18" F/5 Home-Built Dob. with Mike Dudley Mirror
6" F/15 Brass w/ D&G Lens on DS-16 Mount
DS-10 10" F/4.5 Newtonian
LXD650 and LX200 Classic Autostar Converted!
DayStar 0.45 T-Scanner with multiple ERFs
11x80 Meade, 20x80 Celestron binocs (Vintage Japan Made).
A few Naglers and 8mm and 13mm Ethos.
Gadgets and parts everywhere.


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Tom and Beth
Carpal Tunnel


Reged: 01/08/07
Posts: 2019
Loc: Tucson, AZ
Re: Hurst 1/2 RPM Motor Needed new [Re: Skywatchr]
      #2525600 - 07/17/08 11:21 PM

Roger that, Jeff.

And yet if the other guy absolutely, positively HAS to have a new motor....


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Skywatchr
Carpal Tunnel


Reged: 06/03/06
Posts: 2626
Loc: North-Central Pa.
Re: Hurst 1/2 RPM Motor Needed new [Re: Tom and Beth]
      #2525620 - 07/17/08 11:33 PM

Yep, sometimes you get stuck between a rock, and a hard place.

Jeff

--------------------
18" F/5 Home-Built Dob. with Mike Dudley Mirror
6" F/15 Brass w/ D&G Lens on DS-16 Mount
DS-10 10" F/4.5 Newtonian
LXD650 and LX200 Classic Autostar Converted!
DayStar 0.45 T-Scanner with multiple ERFs
11x80 Meade, 20x80 Celestron binocs (Vintage Japan Made).
A few Naglers and 8mm and 13mm Ethos.
Gadgets and parts everywhere.


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JohnH
Carpal Tunnel


Reged: 10/04/05
Posts: 1738
Loc: Squamish BC Moved!!!!!
Re: Hurst 1/2 RPM Motor Needed new [Re: Tom and Beth]
      #2526770 - 07/18/08 03:34 PM Attachment (36 downloads)

The worm turns fine with the motor and attached gear removed. I can easily move it with little resistance with just one fingertip even with 30 lbs of scope, counterweight, spotter and a 41mm Panoptic.


I tested the leaded for the inputs to the motor and they have a high resistance, but not out of line for something that is only rated for 5 watts.

After removing it, I tested the various parts of the external circuit (switch, bulb, capacitor and solder connections) and found they have continuity.

I plugged it back in, still removed so no load on the gear, and it did not turn, it just got hot to the touch.

PS You have to admire whoever machined this mount. The little block of aluminum that he machined out to hold the wiring took at least 18 separate steps on a milling machine.

Attachment

Edited by JohnH (07/19/08 12:09 AM)


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Tom and Beth
Carpal Tunnel


Reged: 01/08/07
Posts: 2019
Loc: Tucson, AZ
Re: Hurst 1/2 RPM Motor Needed new [Re: JohnH]
      #2526971 - 07/18/08 05:27 PM

You probably already surmised this, but your motor is dead. That is GOOD news, because an issue with the worm/drive is not as easily rectified.

BTW, don't throw any of the motor stuff away. You'll need it for when you get the replacement.

Good job on the Fault Isolation, John!


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jwheel
sage


Reged: 01/23/08
Posts: 476
Loc: Fort Davis TX
Re: Hurst 1/2 RPM Motor Needed new [Re: JohnH]
      #2527000 - 07/18/08 05:52 PM

You might also try contacting the Hurst Manufacturing Company

http://www.hurstmfg.com/hurstmfg/index.jsp

I needed a replacement motor for my mount about a year ago and was able to get one from them.

Joe Wheelock

--------------------
16" F/4.5 Newtonian on Parsec GEM (in roll-off roof observatory)
10" Orion Dobsonian
2.4" Jason refractor
Borg 45EDII refractor
15x70 Celestron Skymaster binoculars
Canon Digital Rebel XSi(modified)
18-55mm Canon zoom lens, 50mm f1.8 Canon lens, 105mm Sigma telephoto

http://joewheelock.0catch.com



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astrokido
space wanderer


Reged: 06/09/08
Posts: 798
Loc: Phoenix, AZ
Re: Hurst 1/2 RPM Motor Needed new [Re: Tom and Beth]
      #2527001 - 07/18/08 05:53 PM

Let's see: the motor isn't jammed and you're getting current through both coils, both healthy signs. Have you tried replacing the capacitor?

--------------------
- Gill C. - NexStar 60GT, Cometron CO-100, 10x25, 20x80, Binochair, Nikon D40

The Night Sky Atlas: www.nightskyatlas.com


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gnabgib
sage


Reged: 06/05/05
Posts: 468
Loc: Fall River MIlls Ca.
Re: Hurst 1/2 RPM Motor Needed new [Re: astrokido]
      #2527076 - 07/18/08 06:30 PM

John;
Perhaps the lid on the end got jammed on to far during the accident and is preventing the armature from turning. The lid is just a light press fit so pushing it off a little bit should be fairly easy. Or just remove it to see if the armature is spinning freely. A stuck armature would cause the motor to heat up rather quickly!
My .02 worth
Kevin


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DAVIDG
Post Laureate


Reged: 12/02/04
Posts: 3663
Loc: Hockessin, De
Re: Hurst 1/2 RPM Motor Needed new [Re: Tom and Beth]
      #2527108 - 07/18/08 06:47 PM

Before you declare the motor dead, you need to test the capacitor with a cap checker. You have a reversible motor and if the cap is bad it will do just like you describe, hum and get hot.
I have the same motor and just checked the resistance on the windings. Both Red/Black and White/Black have a resistance of 815 ohms. There is no continuity between the windings. One sign that the cap is bad is continuity thru it when it is electrically isolated. The cap needs to be 0.5 ufm at 250 volts or higher and non polarized. I would also double check the plug and power cord to be sure your getting power to both black leads of the winds. I would check continuity from the prongs on the plug to the each of the windings. You should have low resistance from the hot side of the plug to the both black leads and also low resistance from neutral prong on the plug to either the white or the red lead. If you have low resistance to the red lead you should have very high resistance to the white lead and the condition should reserve when you flip the switch.
www.herbach.com has your motor but it's $170 !

- Dave

--------------------
Homemade 'scopes 8"f/7,6" f/5", 6"f/4, 4.25" Schiefspiegler,60mm Coronagraph,60mm H-alpha system, 4.25" White-light Solar Newtonian,solar spectroscope, 4" f/12, 4.5" f/16 & 6" f/12 Schupmann Medial refractors, 4" Celestar, 19 Stellafane awards 9 in optics

Engineering = Taking what you have and making what you need.


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JohnH
Carpal Tunnel


Reged: 10/04/05
Posts: 1738
Loc: Squamish BC Moved!!!!!
Re: Hurst 1/2 RPM Motor Needed new [Re: DAVIDG]
      #2527515 - 07/18/08 10:57 PM

OK I'll run through the check once more:

Power from plug makes it inside.

Capacitor tests at 504.5 nF which is .5045 microFarads and is rated to 500V.

Resistor tests at 74.5 kOhms. Somewhat irrelevant, as this is only useful for the weird little neon blub that serves as a 'power on' indicator.

Red/Black and White/black leads test at 753 and 760 ohms respectively.

The aluminum cap comes off easily, so that just leaves the gearbox being physically jammed.

I did find the entry for the motor at the site you gave me. However, they say it will be 6 to 7 weeks to get one. I do have a call in to several other distributors, but so far I haven't heard a thing.

I was digging around in a volume of Sky and Telescope for the year 1977, and found a nearly identical setup, with even the same motor. The only difference is it used a three position switch for those frequent trips to the southern hemisphere.

Edited by JohnH (07/19/08 12:17 AM)


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DAVIDG
Post Laureate


Reged: 12/02/04
Posts: 3663
Loc: Hockessin, De
Re: Hurst 1/2 RPM Motor Needed new [Re: JohnH]
      #2528475 - 07/19/08 02:28 PM

Is the switch a double pole, double throw, center off, type or just an On/Off ? The motor is reseversible so if the gear box is jammed you might get lucky and by changing the direction get it to move and free it up. If the switch allows this great, or just flip the position of the Red and white leads and that will change the direction. Good luck.

- Dave

--------------------
Homemade 'scopes 8"f/7,6" f/5", 6"f/4, 4.25" Schiefspiegler,60mm Coronagraph,60mm H-alpha system, 4.25" White-light Solar Newtonian,solar spectroscope, 4" f/12, 4.5" f/16 & 6" f/12 Schupmann Medial refractors, 4" Celestar, 19 Stellafane awards 9 in optics

Engineering = Taking what you have and making what you need.


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JohnH
Carpal Tunnel


Reged: 10/04/05
Posts: 1738
Loc: Squamish BC Moved!!!!!
Re: Hurst 1/2 RPM Motor Needed new [Re: DAVIDG]
      #2528678 - 07/19/08 04:35 PM

The switch has three electrical connections but only two positions.

I tried reversing the poles like you suggested but there is no change. That 6-7 week wait is looking better and better all the time..........


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Skywatchr
Carpal Tunnel


Reged: 06/03/06
Posts: 2626
Loc: North-Central Pa.
Re: Hurst 1/2 RPM Motor Needed new [Re: JohnH]
      #2528964 - 07/19/08 07:54 PM

Boy, it's too bad you couldn't be able to find a decent DC servo motor to replace the AC motor. There has gotta be some way to get it back up and running in less time.

Jeff

--------------------
18" F/5 Home-Built Dob. with Mike Dudley Mirror
6" F/15 Brass w/ D&G Lens on DS-16 Mount
DS-10 10" F/4.5 Newtonian
LXD650 and LX200 Classic Autostar Converted!
DayStar 0.45 T-Scanner with multiple ERFs
11x80 Meade, 20x80 Celestron binocs (Vintage Japan Made).
A few Naglers and 8mm and 13mm Ethos.
Gadgets and parts everywhere.


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DAVIDG
Post Laureate


Reged: 12/02/04
Posts: 3663
Loc: Hockessin, De
Re: Hurst 1/2 RPM Motor Needed new [Re: Skywatchr]
      #2529132 - 07/19/08 09:46 PM

Just to be totally on the safe side I would replace the cap. In a couple of very rare ocassions I have seen a cap check OK using a tester but be bad when high voltage is applied.
I just pulled the back cover off of my motor and right below the top coil is the armature. I can stick a small screwdriver in the gap and move the armature. You might want to see if you can do this on your motor. Maybe just moving it will free something and get you back in business.

- Dave

--------------------
Homemade 'scopes 8"f/7,6" f/5", 6"f/4, 4.25" Schiefspiegler,60mm Coronagraph,60mm H-alpha system, 4.25" White-light Solar Newtonian,solar spectroscope, 4" f/12, 4.5" f/16 & 6" f/12 Schupmann Medial refractors, 4" Celestar, 19 Stellafane awards 9 in optics

Engineering = Taking what you have and making what you need.


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JohnH
Carpal Tunnel


Reged: 10/04/05
Posts: 1738
Loc: Squamish BC Moved!!!!!
Re: Hurst 1/2 RPM Motor Needed new [Re: DAVIDG]
      #2529882 - 07/20/08 11:16 AM

The motor is a pretty tight affair, without too much room.

I can see a plastic spacer of sorts underneath the two plastic discs that cap the top winding and some metal under all of that.

I'll go get a thin, sharp punch to pick at that and see if that moves at all.

Nope, it doesn't move. It either is jammed or isn't meant to move. Hmmmmmmmmmmmm.

"These kinds of puzzles, do not fit together."

Edited by JohnH (07/20/08 01:30 PM)


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