Help!! EQ3-2 Replacement Stepper Motors???

[smutly]

Hi all

I have an EQ3-2 with dual axis motor drives which have stopped working properly recently.

I think the dreaded Chinese grease in the mount was partly to blame for wrecking the motors. This has now been all cleaned out and also cleaned out the motor drive gearboxes.

The stepper motors though (on their own) don't feel like they have much torque behind them anymore and when I put them back on they intermittently work and more often just sit there chugging away but not moving anything.

I was wondering if you can just buy new stepper motors to replace the old ones, otherwise you have to buy the whole setup again.

Out of the 2 stepper motors only 1 had a label on it saying: 42PM48L BZ NO:20101012

I have tried searching google for these numbers and found some 42PM motors but there were different variations of the rest of the numbers and nothing exact, so i don't really know if there would be an alternative that would be suitable.

Any help and advice would be much appreciated as I don't have much more hair to pull out.....lol.

[smutly]

Here is some pics to explain.

The motor and gearbox together.

The motor and gearbox apart.

The motor and tape measure.

[35mmslr]

Hi Jeff,

Sorry to hear about your troubles. I was also looking for replacements for my EQ3 but had no luck. I need a new gearbox as mine has shredded teeth. If you do invest in a new kit I would be interested in buying your old RA motor with the gear box so that I may get mine going again.

Hope you get some answers soon

Regards

Dave

[JamesF]

Can't help much, I'm afraid, other than to suggest that a read of this thread might provide an alternative solution:

http://stargazerslounge.com/diy-astronomer/104457-diy-tracking-drive.html

James

[JamesF]

Actually, out of interest, is that the DEC or RA motor in the photos above? And are there two nylon gears in the gearbox or just the one?

My DEC gearbox only has one nylon gear -- the one driven by the motor. stan26's posts suggest that he has a nylon gear on the output shaft as well. I'm wondering if the design has changed.

James

[Bizibilder]

Swap the RA and Dec motors to keep you going until you can find a replacement.

Just a thought - have you made sure that no gears are slipping on their shafts - I bet they are only pressed on and may have "worked" a bit?

[malc-c]

Can't help with the motor - but the gear ratio etc can be found on the EQMOD website EQMOD Pre-requisites

My guess is that they are 1.8 degree per step,

[malc-c]

I've juts googled the part and came up with this

ADJ MotorPanTiltDoubleFeature 42PM48L-01-10A DJ Shop

From one of the other forums I found this

from the part number that that is a 42mm (NEMA 17) stepper, 48 steps per revolution

[JamesF]

Hmmm. Not sure I'd fancy trying to make that fit on the existing gearbox and into the motor shroud.

Removing the PCB and re-wiring shouldn't be a big deal, nor cutting down the mounting plate, but drilling and tapping the plate without getting bits of swarf inside the motor could be tricky and transferring the driving gear might also be awkward.

I'm not sure I can see a way around that at the moment.

James

[malc-c]

James, I agree. And searching for (NEMA 17) stepper turns up the traditional square stepper design like those in the HEQ5 etc.

Jeff, maybe it's worth contacting the importers OVL to see if replacement parts can be purchased ??

[35mmslr]

Malcolm, who are OVL? I need to get a new gearbox and google is providing nothing useful.

[garethmob]

Ovl is the main uk importer of skywatcher (synta) scope products

Sent from my iPhone using Tapatalk

[Cornelius Varley]

Optical Vision Limited.

Peter

[JamesF]

They are Optical Vision Ltd:: Stargazing Telescopes, Binoculars, Spotting Scopes, Microscopes by OVL

I very much doubt that they'd be able to supply you with spares, but if there's someone in the UK that sells them then perhaps they might be able to point you in the right direction.

I have to admit however that I'm not too confident of a positive outcome. I imagine a lot of this sort of stuff is boxed up in China and sold on as is.

I'd be keen to get hold of a spare gearbox myself, if only so I could take one of my old ones apart completely to see if it's possible to get rid of any more of the backlash. As there's a reasonable chance that it might not all go back together again afterwards though, I shan't even think about it unless I have a spare first.

James

[35mmslr]

Thanks. I have contacted OVL to see if they can help out. Fingers crossed.

[smutly]

After a fair bit of hunting info and waiting for emails (OVL) with not much joy i have come to the conclusion that it's going to be easier to by the complete setup again.

Here is more info i have found out from scouring other forums.

"Google doesn't give you much.

However it is obvious from the part number that that is a 42mm (NEMA 17) stepper, 48 steps per revolution, and it almost certainly has a gearhead on it (because 48 steps per rev is quite coarse).

You could try this one - http://www.deejayladen.com/de/ADJ-Motor ... 1-10A.html

Does yours look exactly like this? I'm not sure if this one has a gearhead (it might).

I don't know how many teeth are on the worm wheel of the EQ3 / CG4 because that would determine the gearhead ratio. But if its 144 teeth like the Vixen Polaris (I heard the CG4 is a Polaris clone) then you could use the exact same motor that Vixen uses - the Nippon Pulse PF-C42H48-C1."

"The motors look very similar (ignoring the gearbox on the top of mine and the mounting brackets). The coil resistance in mine is 17 Ohms which lead me to believe that I have 42BY48L03 (15 Ohms). However, the model number was different (BY instead PM) but then I tried adding 03 to my model number and searching google - it came up with this webpage http://www.motionking.com/Products/PM_Stepper_Motors/42PM_Stepper_Motor.htm . The motors listed there have the same specs as the ones you have found so now I know that my 42PM48L is just a rebadged 42BY48L. Interestingly the BY motor is called PM motor on the webpage but has BY in the model number.

Also I noticed that my motor has the centre wire removed from the coils to make it bipolar only.

So my suspicions were right, the original controller is "under-powering" the stepper motors. The motors are rated at 19V, 1.27A and they are running at 6V, 0.35A only. I suppose that with all the gearing there is enough torque to rotate the mount at 6V and this will save the battery power."

JamesF "Actually, out of interest, is that the DEC or RA motor in the photos above? And are there two nylon gears in the gearbox or just the one?

My DEC gearbox only has one nylon gear -- the one driven by the motor. stan26's posts suggest that he has a nylon gear on the output shaft as well. I'm wondering if the design has changed."

The photo shows my ra stepper and dec gearbox. There is only 1 nylon gear but its moulded into a large gear one side and a smaller one the other.

Bizibilder "Swap the RA and Dec motors to keep you going until you can find a replacement."

I have done that but i found that when the dec motor is used on the ra lead of the controller the motor works in reverse. So i am going to try it out in the S position (instead of N) and see if it tracks ok.

35mmslr "If you do invest in a new kit I would be interested in buying your old RA motor with the gear box so that I may get mine going again."

That would be no problem, i just hope you actually GET A RESPONSE from ovl.

It is just a pain that a multi part item (motor drives) is sold with no support for obtaining spare parts available to order.

I own an old Manfrotto tripod and had a leg section clamp break on me, i checked their support and found i could order every single item of that tripod.

SkyWatcher is a large brand, why can't they do this too.......???????

[Rob]

Jeff,

Keep posting on astrobuynsell asking for a motor only.. you never know these things do come up!

Rob

[smutly]

Here is an update:

Thanks to JamesF for sending a working spare motor for me to try and solve the problem.

I tried the replacement motor, on the ra cable, before putting it on the mount and it turns anti-clockwise (backwards) at x8 but does not turn clockwise (forwards) at all even at x8.

JamesF Assured me the motor worked before he sent it and asked me to try it on the dec connection.

I checked the replacement motor, and my other 2, on the dec cable, at x8, and they all seem to work ok off the mount, and if i try to stop them with my thumbnail it starts to grind the nail down.

So i tried them again on the ra cable and:

My dec motor works on tracking and x8 forwards and backwards but stops real easy on thumbnail test.

My ra motor works intermittently on tracking and works x8 forwards and backwards but stops real easy on thumbnail test.

The replacement motor now works intermittently on tracking and works x8 backwards but not at all forwards and stops real easy on thumbnail test.

I thought what the blumming hell is going on here so i took the handset apart and got my multimeter out (which i am not overly knowledgeable about any other settings) and checked voltages.

Direct power into handset is 6.1V

RA volts as it pulses goes a bit like this : 3.3, 3.3, 3.3, 3.2, 3.1, 3.0, 2.9, 2.8, 2.7, 2.6, 2.5, 2.4, 2.2, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.3, 3.3.

RA volts x8 : 3.2 solid

So i don't know whether it's supposed to do that?

Could it be the handset that has been causing the problems all along?