Afbrændt LDX75

[Bjørn SandåkerDeltager Neutron star]

Det var flott at det ordnet seg! Jeg håper å slippe å oppleve det der …

Mvh,
Bjørn

[rick78Deltager Asteroid]

Hi Guys,

I know this thread is old, but I have a motor unit fault on my RA motor on my LXD75. I bought it used and it has been working fine until yesterday, while at Avnø. I accidentally set slew speed to max (9) just before, I think. I heard nothing special, it just stopped moving. I could not smell anything burnt either. I thought maybe low batteries, since I was on the D battery pack. I put on my power bank 12v, and the problem is the same. Pushing right or left on the hand set does nothing, and after a few minutes after powering it on, it comes with the MUF error across the hand set. I have a backup #497 hand set and cable, where the problem is the same.
I was going to open it up and see if something is burnt, or try to clean connectors, but I cannot find a hex small enough to fit to take off the black plastic cover on the motor.
Can anyone offer advice?
Please feel free to reply in Danish 🙂

Thanks, in advance.
Rick

[rick78Deltager Asteroid]

Hi Guys,
I managed to get my RA motor off, using an American hex key (Arghh!). I only had metric hexes, but found a set at Biltema 🙂

I cannot see any blown capacitors, and as i said, there is no burnt smell.
Does anyone have an idea on what could be wrong?
I have a simple ohm meter, but I am not very good with it and do not know how to test with it.

Thanks,
Rick

[rick78Deltager Asteroid]

Ok, I swapped the motors and now the dec will not turn.
While I had them off, I could actually turn the gear. it was not frozen and it seemed normal.

So my boards seem ok. Now I need to figure out if the motor can be fixed.
Any one know if I can get a motor that would fit this mount?

Thanks again,
Rick

[jonas.cDeltager Super Giant]

I bought a frozen LXD75 mount many years ago. The owner said he couldn’t get it to work. What I found was that the worm shaft was bent and had locked everything. It was easily fixed as the shaft could be bent back using only my hands. But I guess you have looked into this ..

/Jonas

[rick78Deltager Asteroid]

Hi Jonas,

thanks for the reply. The motor would not turn on even unmounted, so it seems it is in the motor itself. I will try to figure out how to troubleshoot it and see if I can repair it. I never messed with an electric motor before.

I guess Youtube is my friend 🙂

Can anyone recommend a shop, or someone in Copenhagen that could look at the motor itself?

Thanks again,

Rick

[erik.nielsenDeltager Super Giant]

Is the IC 4947A blown???
Look the start on this thread: It happens, if the motor is blocked during action. Often you can see a small dent on the surface, as seen on my picture.
By the way, i have my old LDX75 toothed belt modifyed for sale, 1173,75 kr, not negotiable
regards Erik

Erik Nielsen2016-10-04 10:00:08

[rick78Deltager Asteroid]

Hi Erik, thanks for the reply. No, I do not believe the IC is blown. It looks fine and if I put the dec motor on the RA board, it works fine. Connecting the RA motor to the dec board fails. So the motor itself seems to be the issue.

Thanks for the offer on your modified LDX75. I will keep it in mind, if I cannot get this fixed.

Regards,

Rick

[jonas.cDeltager Super Giant]

Try http://www.2astro.dk/ who sold Meade product many years. Maybe they still have a motor lying around.

/Jonas

[rick78Deltager Asteroid]

Thanks Jonas. I will try them.

Rick

[rick78Deltager Asteroid]

Solved!

Thank you all for your attention on this issue. I finally had some more time to sit down and troubleshoot with a multimeter. I am such a noob on electronics, but I managed to figure out a continuity test on the wires and I found a break. The break was in the middle of the coiled up positive wire. It seems strange that it broke there because that is tucked in the cover nice and snug. Anyway, I soldered it again and placed new shrink tubing on it.

A 9V battery turns the motor. That was a great sound to hear the motor turn!

Now I just need to reassemble it and get back outside!

Thanks again,

RIck

[jonas.cDeltager Super Giant]

Great that you found the defect!

/Jonas

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