SydLappen

On 16/05/2024 at 22:43, malc-c said:

So if I follow this right.

• Dec motor connected to the DEC connection the result is a 5-15 second run and then stops
• RA motor connected to the RA connection the motor runs fine 
• Dec motor connected to the RA connection the motor runs without issue
• RA motor connected to the DEC connection and it runs for 5-15 seconds

This does indeed suggest that the motors are fine and points the finger at the DEC board as being the cause.  

Its not clear form the pictures as to how they connect... Are the RJ ports used for inter board connections or are they used to connect the steppers to each board ?  If they are  interlink connections and you have access to a multi-meter (DVM) then you could check continuity of the cables (if you do this by touching the solder joints of the RJ connector with the cable in place then it also confirms the connection of the RJ plug and RJ socket as well).  If the fault remains the same regardless which cable is used between boards then that rules the cables out.  

The part that I'm struggling with is what's causing it to run fine and then cut out in that 5-15 seconds.  I'm not familiar with the system myself, but is there an option to update the firmware via a PC application.  If so you could see if that works.  If the firmware flashing is performed without any errors and the fault still occurs then it could possibly be the driver side of the board.  Do any of the chips on the DEC board get hot when the motor runs ?

You mention that the DEC motor seems to buzz when it stops.  Can you confirm that the motors used are steppers and not DC servo motors (I can see what looks like an encoder disk and the letters "enc" are visible on the silk screen of the PCB).  It may be irrelevant as the driver chips look to form an H bridge and if one side has failed then it might explain the buzzing from the motor.

Chances are that a replacement board isn't available as a single litem and so a complete package has t be purchased.   

Depending on the age of the mount you may have a case under consumer law to have the board replaced.  The fact that it might be out of warranty is irrelevant as its the fact that you would normally expect something to last for a reasonable length of time.  The only caveat  is that it would be clear that the mount has been opened up and "messed with" .  If getting the retailer involved is not an option then before you look at getting a complete new goto kit let me have details of the chips involved and I would be willing to have a go at repairing the board.  I can't promise I will be able to fix it, and there would be some costs involved such as postage and parts but it's an option.  But you then have the weigh up the costs against that of a new complete kit.   Drop me a PM if you want me to take a look at the board and we can go form there.  I can make out that the microcontrollers used are PIC 16F chips, but can't make out the actual part numbers.  Same goes for the smaller chips. If you could let me know what they are I could at least confirm that I can still get them.  If the drivers have been discontinued / or impossible to source then that would scupper the repair before we started 

 

 

Hi,

I went back and checked a few things over, so it took a while. But this is what I found (or not):

Are the RJ ports used for inter board connections or are they used to connect the steppers to each board ?
>> Yes, that was not so easy to see. They are use to connect RA board to DEC-board and handset to board (RA).
   
If they are  interlink connections and you have access to a multi-meter (DVM) then you could check continuity 
of the cables...
>> All seem normal except the one marked red (see picture below), gives a 10 ohm reading instead of 0.9-1 that I get on the others. Not being particularly experienced in electronics 
(not touched it since high-school I assumed a 1-1 relation between the connectors.
Not sure if that is relevant? 

If the fault remains the same regardless which cable is used between boards then that rules the cables out.  
>> I have tried with switching RJ cables and it gives me the same error.

The part that I'm struggling with is what's causing it to run fine and then cut out in that 5-15 seconds.  
I'm not familiar with the system myself, but is there an option to update the firmware via a PC application.  
>> From what I can see I run the latest version, 2.3

Do any of the chips on the DEC board get hot when the motor runs ?
>> No, not that I can feel.

You mention that the DEC motor seems to buzz when it stops.  
Can you confirm that the motors used are steppers and not DC servo motors 
(I can see what looks like an encoder disk and the letters "enc" are visible 
on the silk screen of the PCB).  
>> I cannot find any information on the Bresser site when it comes to this kit, there are others they sell where it says that it's steppers. So it's likely these are I guess. 

>> There is one thing though that puzzles me particularly, as I can't see any logical reason for it (if the problem is the DEC PCB), when the DEC motor stops working after a while (after you run a couple 5-12 sec. runs), the RA motor stops working as well. 🤔

On 13/05/2024 at 12:33, malc-c said:

To rule out the motors, remove them from the mount and see if the same issue occurs.  If it does then this suggests that the issue is electronic related rather than a mechanical issue such as a stuck bearing, thick grease restricting movement or bent shafts etc.   The next thing to try is to swap the motors over at the point where they connect to the motor board.  If the issue moves with the motor then this would suggest the issue is a faulty motor which will need replacing.  If the issue doesn't follow the motor, and remains on the same output then both motors are fine and the issue is with the control board or handset.  I've not read through the linked thread, but commercially there are two options available, a basic hand set or a goto handset. If its the goto handset then the fact the motor responds to the initial command to slew to a target suggests the handset would not be the cause.

My gut feeling is that it's either a connectivity issue (the mount seems to be very similar to a Skywatcher EQ5 which used DIN plugs and leads between the two motors), so its worth checking that the motor wires are soldered nicely to the back of the DIN terminals, or that there is continuity between pins at either end of the cables. There was a thread where someone else has a fault on one axis and it was down to one wire on the back of a DIN socket that was just hanging on by one strand which would disconnect through movement).   

If after checking that and no bad solder joints are found, and all connections and cables check out OK then this just leaves the motor board as the cause.  If it all points to the board as being the culprit then it's likely to be one of the H bridge driver chips.  However replacing one is not something that someone with limited soldering experience could do.  99% of the Skywatcher boards I've repaired have been down to damage to the main processors, but I have replaced one H bridge chip on one board as it had no output whatsoever. 

Are you able to take a nice photo of the motor PCB and post it so I can see what components are used ?  I can then advise further.

Hi Malcolm,

Thank you for the support! 
I have tested the steps above and I got these results...

"rule out the motors, remove them from the mount and see if the same issue occurs.":
I did and it gave pretty much same results as before; 
DEC motor - same, runs 5-15 sec then stops. It runs a bit longer in one direction and in the direction where it runs shorter it makes more noise but I'm not sure that has any significance.
RA motor - same, runs as long as you press the arrow buttons.

"swap the motors over at the point where they connect to the motor board.: 
Only one at the time was connected (see photo), i e I did not swap and connect DEC to RA board and vice versa at the same time (it caused the motors to "hack" after a second or so). 
The results were telling:
DEC motor connected to RA board - DEC motor runs as long as you hold the button!
RA motor on DEC board (see photo) - motor stops after 5-8 sec.

I have checked the board and the wires but I can't see anything that looks loose or bad soldering (see photos)
It's of course possible that there is a bad connection in the cable that connects the boards but I can't see that.

So, I guess we are talking about having to change the PCB?

Kind regards,
Magnus

21 hours ago, Carbon Brush said:

I don't know this mount, I am assuming it has DC motors, not stepper motors.

Your first step is to determine what fault you have. From the report it could be.
Power supply shutting down.
Drive electronics shutting down.
Motors being asked to drive into a stiff (not free running) gear.

Do you have a basic multimeter? If not you are very much in the dark.

Connect an ammeter to the supply. Run one motor at a time moving only the mount - no scope or weights attached.
A high current draw is a clue to something sticking.
Monitor the supply voltage when moving the motor - see if the voltage drops.
Try running the supply into car bulbs as another check on power delivery.
Tail/side lights take about 0.5A. Brake/indicator lights about 1.75A.

Hope something in there is useful.

David.

Had one, time to get a new. 
Thanks!

4 hours ago, michael8554 said:

Does the Dec motor run for exactly 5 seconds on the slowest and highest slew speeds ?

That would give a clue to the source.

Michael

Tried it now, pretty much the same result - once or twice it runs for up to 12 sec if use low speed, then it drops back to 5 sec 🤷‍♀️

The handset use Exos EQ v 2.3, it's just called Bresser GoTo Handbox. 

I use a 12V, 3A. I changed it recently as Bresser said that 3A would be better.

What puzzles me is that 1 - the RA axis motor runs fine, does not stop when I use the "guide arrows" (handset), you cam run it back and forth all you want, and 2 - that on the Dec axis the motors run exactly 5 sec, then stop, then run 5 sec again, and continue to do it until the won't run when I hit the arrow key. 🤷‍♀️

Good evening,

Have had to drop this for a while but now all is re-assembled (new ball-bearings, cleaned, etc.  (https://stargazerslounge.com/topic/418182-bresser-messier-exos-2eq-5-goto-worm-gear-problem/) 

I now have come to the second problem (was hoping that it would disappear...), that the Dec axis, when I move it using the handbox, runs for 5 sec intervals, 2-10 times (sometimes more, some times less), then everything stops. You cannot use any of the axis motors  , none of the arrow buttons work, but it sounds like the engines are activated (low buzzing sound).
Makes no difference if you go clock-wise or counter clock-wise, and it does not occur on the R.A. axis/motor.

Any ideas??

Cheers,

Magnus

12 hours ago, Rusted said:

Does the roughness occur in the absence of the wormwheel? Let's assume you are talking only about the worm in its housing. [As pictured.]

Ease off the end pressure adjustment [if any] on the worm bearings until you obtain shake-free smoothness of turning.

"Cogging" is extremely commonplace where ball bearings are overtightened. Typical of an overtightened bottom bracket bearing on a bicycle or headset. [Forks] Though much less common after journal bearings took the place of loose balls in cups.

I am concerned about the broken casting just above the worm in your picture. Is there any debris in the worm grease? 

Thank you for the explenationsons!
I'll try that.

About the casing, I checked after you mentioned it, it's OK. There was just string of dirt.

Thanks!

It's true that wear is not so likely, they are not sitting in an engine after all. My thought was more some sort of damage, since there is a slow sort of vibration when I turn the cog wheel.

I suppose it's not very expensive to change them? Just to be on the safe side... 

Hi!

I have bought a second-hand mount and I'm trying to make it work OK (found problems as soon as I tried photography). As it's the first time I deal with this type of mechanics (has mainly been in cars and boats before 😝) I am bit lost...
The worm gears, when I turn the cog wheel on the right, it does not turn effortlessly and smoothly (I imagined it would) but with a bit of resistance and with some "choppiness"? A bit like turning a ratchet wheel, it's a bit hard to describe... 😬

Is it normal or do I need to change the ball bearings?

All advise is welcome

Thanks!

Magnus

PS. Then I need to adjust the gears, but that's next step  

Swedish and living outside Malaga.
Have decided to take up an interest I had as a teenager 😀

Trying to get my Bresser Messier HEQ5 exos/2 up and running 😝