Meade 8" LX90 ACF - "Motor Fault"

[julianh72 (Julian)]

Sorry if this has been asked and answered - I'm new here - I did a search, but didn't find anything that quite matched.

I'm helping my Dad set up his new 8" Meade LX90 ACF. He has ordered the 12V power supply, but it is on back-order, so we tried to get it going with 8 x C- cell batteries (brand-new Energizers).

We turned it on for the first time yesterday, and all seemed good - the hand control beeped and powered up, the scope did a little dance, and then it asked to be pointed to some aligning stars. Great!

We powered down, took it outside, and powered up. Beep! Beep! Beep! "Motor fault“. Power down, check battery polarity and wiring connectors, power up - same result! :-(

Now we can't get past this message, and the scope won't move under powered control, but it still moves freely when the locks are loosened back.

There's nothing in the owner's manual about this - is it a known issue?

Thanks in advance.

[brian nordstrom (As avatar)]

Hi Julian and welcome , I would join the 'Yahoo Group's , Meade LX90 user group ' do a google join up ( its free) and I bet you will find then answer you need , they have 1000's of world wide members .
Brian .

[Barrykgerdes]

Most common cause of this fault is battery voltage being low. I regularly got this fault when running on batteries. New batteries fixed the problem but the batteries did not last long

Barry

[Astro_Bot]

Whilst the no-load voltage of fresh alkaline batteries may be alright (somewhere around the nominal 1.5V), under load, that voltage drops fast. Driving a high-power device like a motor will drain the batteries quickly, but more to the point, the internal resistance will climb very fast and the first thing you should notice is a drop in the loaded voltage, although the battery will still have a fair bit of life left in it - fine for torches and portable radios, but not for much else.

The voltage drop may be sufficient to fall below the minimum required for the LX90 mount.

[julianh72 (Julian)]

Thanks for the response guys! Sounds like the first thing to try is to get a suitable external battery pack and see if that sorts it.

The frustrating thing is that my Dad ordered a power pack with the scope, but it hasn't arrived yet. The scope shop lent him a battery pack, but they haven't given him a cable that will fit in the socket on the mount. :-(

Does anyone know how many Amps the Meade drives and hand control unit will draw, so I can try to find a suitable power pack until the real deal arrives? (That's another thing that isn't mentioned in the user manual.)

Thanks!

[brian nordstrom (As avatar)]

That's the one , thanks Barry .
Remember the bad old 18volt days ??? .

Iv'e a Celestron on the way and welcome to the good old days ,,,, carbon fibre as well mmmm,,
,,,,checking out the hype ...

Brian.

Originally Posted by Barrykgerdes

Most common cause of this fault is battery voltage being low. I regularly got this fault when running on batteries. New batteries fixed the problem but the batteries did not last long

Barry

[AndrewJ]

Gday Julian

The scope will ( normally ) happily run on 1.0-1.5A at max slew.
That said, based on your description, you are getting "Motor Fault" during booting, not a "Motor Unit Fault" when running.
( A MUF due to low power etc always results in an immediate reboot of the scope, with no beeps )
Sooooooo, if it is the former, ( and the constant beeping indicates it is ), then it is not normally associated with power supply.
On booting, the handbox asks the RA motor card what type it is, so it can configure itself accordingly.
If it gets no response from the motor card, it starts beeping and declares "Motor fault" ( which is a really confusing message )
If you hit enter whilst it is beeping, you can get past the warning.
Try the up down slew keys and they may work.
If they do, turn off the scope and swap the Hbx cable end for end and try again ( this swaps the wires used for the different comms functions ).
Does it now start up????
Also, what firmware is it running.

Andrew

[julianh72 (Julian)]

Thanks everyone, and AndrewJ in particular. Next time I head over to my Dad's place to try to set up the scope in a couple of days, I'll take along a 12V / 2A power pack and a bunch of leads (the ones we had hand wouldn't fit the scope base jack),. I'll try swapping cable ends etc to see if that helps too. And of course, we'll get back onto the scope shop that sold him the scope, and get them to deliver a working power supply.

Thanks again - really appreciate the help! I hope my next post is a positive one - maybe even with a couple of photos?

[GB]

Hi Julian,
I have the LT model and i used a SCA jump start battery from Super Cheap Auto which cost me only $49 when they have a sale.
Hope you can get some lead from the forum.
Cheers

[acropolite (Phil)]

Julian, there shouldn't be any issue with brand new energisers unless you have faulty batteries, I ran my (non ACF) LX90 on C cells for quite a while. Unless the design of the LX hardware has changed dramatically there should be no reason for the unit not to run happily on C cells.

[julianh72 (Julian)]

We were having a tinker today, and I think it is most likely a fault with the handset cable (or possibly the handset, or the motors / motor controllers).

We've now had two occasion when on first power up it starts to go through it's initialisation dance, but as soon as you start the alignment procedure, or try to manually drive it, we get the "Motor fault" message. After that, no amount of power down, power up, disconnect / reconnect the cable, etc, seems to clear the fault. (But sometimes disconnecting the handset cable and reconnecting it results in no power at all to the handset, which points to a possible fault with the handset cable and / or end connectors at either the motor drive base end or the handset end?) We haven't yet managed to get it under manual or automatic control at all.

I found a 12V power pack with a suitable end jack which powered it up fine, but it generated the same "Motor Fault" error message as running on batteries, which suggests it probably isn't a power supply problem.

Oh well - we'll get in touch with the local supplier, and see if they can diagnose it and fix it. First thing would probably be to try a new cable and / or handset, to see if that fixes it; if not, it sounds suspiciously like a fault in the motor-drive base, which will be a major pain, because presumably that would need to go back to the factory to fix.

[AndrewJ]

Gday Julian

We were having a tinker today, and I think it is most likely a fault with the handset cable (or possibly the handset, or the motors / motor controllers).

Well that narrows it down a bit

but as soon as you start the alignment procedure, or try to manually drive it, we get the "Motor fault" message.

Do you mean "Motor Unit Fault"??? and does it reboot immediately???
( The exact wording of the error is important here )
The "Motor Fault" message ( with beeping ) can only occur during the initial bootup process, so i suspect it was really a MUF and reboot??

I have seen some Hbx cables that fit so badly that they lose contact with the slightest bump. This would line up with your intermittent symptoms.
Can you try the same test but this time get someone to forcibly hold the Hbx cable in the scope and Hbx sockets so they cant wiggle during operation.
Does it work now????

Andrew

[julianh72 (Julian)]

AndrewJ

Thanks again for the feedback. I'm afraid its a bit frustrating trying to resolve this via Internet Forums, as I only get to have the odd play with the scope at my dad's place, then post my questions / responses , but when I get an answer, I'm kilometres away from the scope! Next time I'm over there, I'll see what happens if we apply some positive tension to both ends of the cable, to really force it against the contacts at each end.

The message on the handset display is "Motor fault", not "Motor unit fault", and it happens during initial boot-up, after the firmware message. (Sorry - I forgot to check the firmware version - I'll check this on my next trip.) It will apparently stay in this state (i.e. beeping and flashing "Motor fault") indefinitely, and it doesn't reboot itself, but pressing "Enter" once or twice will clear the error message and move on the the next screen, but there is no motor control.

The flex cable seems to fit properly - it clicks in solidly at both ends (like a telephone / WAN cable), and doesn't seem to break contact if you wiggle either end while holding the handset unit. Having said that, we have noticed that once or twice if we unplug it and plug it back in, then power up, the handset won't power up, so I am leaning more and more to a faulty cable or connectors.

Once we get the "Motor fault" and beeping, hitting "Enter" once or twice clears it, and it goes on to the Menu / Alignment screen, but trying to drive the scope manually using the arrow keys achieves nothing - I've tried pressing "9" (to get the fastest slew speed) and then using the arrow keys, but there is no sign of life in the drives at all.

As an experiment - I hooked up a length of WAN cable (which has the same type of plugs at each end), but the handset didn't power up at all. I assume the Meade cable uses a different pin-to-pin wiring arrangement than a WAN cable?

[AndrewJ]

Gday Julian

The message on the handset display is "Motor fault", not "Motor unit fault", and it happens during initial boot-up,

OK, thats good, as the last post you noted the following,

it starts to go through it's initialisation dance, but as soon as you start the alignment procedure, or try to manually drive it, we get the "Motor fault" message.

and that didnt make sense ( time wise ) as to when it occurred.

hitting "Enter" once or twice clears it, and it goes on to the Menu / Alignment screen, but trying to drive the scope manually using the arrow keys achieves nothing

Drat. I was hoping that at least the Up/Down may have worked, as that uses a different motor card, and would have proved that some part of the comms was working.

As an experiment - I hooked up a length of WAN cable

Experiments like that can get very expensive.
A std cat5 cable is wired opposite to the Meade Hbx cable,
ie 1-1 .. 8-8 vs 1-8 .. 8-1
You risk putting reverse polarity into the hbx doing this.
The fact the Hbx still fires up is good, but i hope nothing else got damaged. If you are ever unsure of the wiring, hold the plugs on the cable end to end to see how the wires are arranged.

Edit
Also, this site
http://jan.eaglecreekobservatory.org/
has a wealth of general information for LX90s and 497Hbxs etc


Andrew

[julianh72 (Julian)]

AndrewJ

Thanks again for the response - and thanks for the link to Jan's Meade LX90 page.

With respect to the sequence of actions - please note that we have only twice managed to get past the "Motor fault" message, so I'm not sure what the "normal" characteristics at start up should be - it's possible that I got the sequence slightly wrong. My recollection is that on those two occasions, it went like this:

1. Turn power on - LED illuminates on the base
2. Hand unit lights up, and displays the firmware message. (I still haven't had a chance to check the firmware version)
3. Scope slews fairly quickly side to side and up and down (not necessarily in that order) - maybe 30 degrees arc or thereabouts - I assume this is the scope just checking the drive controls are working, scope is moving freely, etc
4. Hand unit asks for location and time zone information (I assume the GPS hadn't got a lock yet) - enter the relevant information
5. Hand unit displays the options for initial alignment - choose "Easy (2 star) Alignment".
6. Hand set displays a star name for alignment - accept this (we were doing an indoor day-time set up, so it doesn't really matter what star it chooses), and scope slews to what seems a plausible location
7. Repeat for a second star
8. Scope is now "aligned", so we thought we would try a "Go To" - pick Jupiter
8. "Motor fault"

As I said, that's all from memory, so it's possible that a couple of steps are out of sequence, but it went something like that on both occasions. Every other time we have powered up, we get the "Motor fault" message straight after the Firmware version message, and we don't get to see the Location and Time settings etc. There is no response from the slew motors when we use Enter to get past the "Motor fault" message and try manual powered control.

Anyway, we have contacted the shop that sold the scope, and we have to take it back to them for diagnosis - hopefully it is a simple enough thing to fix.

[AndrewJ]

Gday Julian

With respect to the sequence of actions - please note that we have only twice managed to get past the "Motor fault" message, so I'm not sure what the "normal" characteristics at start up should be

Understood. Its just in this case, the exact wording and timing of the error message was critical for diagnosis, and the description given didnt match the expected error.
Hopefully the shop will find it quickly.

Andrew

[julianh72 (Julian)]

Well, it turns out that it was all down to a faulty handset or cable. Took it back to the shop, where they took a handset and cable off another Meade, plugged it in and it worked perfectly. We left with the replacement handset and cable, and have successfully initialised it at home, "Go To" works, etc - All good!

Thanks to all for your advice.

Now all we need is some clear skies....

[brian nordstrom (As avatar)]

That's good news , kinda makes you wonder how it got sold with that HBX or cable ?? .
Enjoy the scope they are very good when working well .
Brian.

[julianh72 (Julian)]

Thanks everyone for your helpful comments!

We managed to get the scope's electronics working yesterday (Saturday), and this evening started out almost cloud-free, so I went round to Dad's place and we got the telescope set up outside. Five minutes later the set-up routine was complete - it really IS as easy as it sounds in the User Manual!

We dialled in "Go To Moon" (which was a very narrow crescent, very low in the sky), and the scope pointed itself right at the Moon, with a great eyepiece filling view - very nice!

Next up was "Go To Jupiter" - a few seconds later we were looking right at it, and the motors tracked beautifully, keeping it centred very nicely in the field of view. The belts and the 4 Galilean Moons were all very easily discernible. (No Red Spot, though - presumably it was round the far side.)

Did a few stars and the Great Orion Nebula before the clouds closed in - not bad for a "First Light" session!