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Any ideas on repairing a (slightly!) blown motor board ?


Astro-Geek
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Guys you are too kind....

I must admit I'm getting quite confident now at repairing these boards... 😉  I had no idea back in April 2020 when we fixed that first set of boards would it lead into what has now become a small time hobby :)  I've lost count now, but we must be approaching repairs in to double figures by now.   Mind you looking at these newer boards, even if the processors can be reprogrammed, the thought of trying to solder an ARM chip scares me 😟

I still have enough 16F886's for two more repairs, but have ordered a few more direct form Microchip to give me enough of a buffer given the current shortages.  I do get a lot of enjoyment from fixing these faulty boards, not just the achievement in turning something from non-working to working again, but knowing that I've helped out fellow astronomers and members of this community.  Your comments back that up and I'm really grateful for the support.

As long as I can get the parts I'll try my best at fixing 'em  :)

 

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Uhmmm... sad news.

Having repaired the HEQ5 board as detailed in Saturdays post the kit was repacked and returned to the owner, which was received today.  I was saddened and gobsmacked to receive a PM stating that the handset reported the original RA no response message  had returned and the stepper motor sounded terrible....

I'm shocked as the repaired board worked fine as you can see form the video, and that was just one test.  I spent best part of Saturday afternoon, power cycling the board and every time it worked faultlessly.  I believe the owner is using the handset and hasn't used some form of EQDIR cable, so that would mean the only different component in the equation is the power supply.  I use a Meanwell LVP 60-12 constant voltage supply.  This provides 12v at up to 5 amps so is more that capable of providing the 2 amps these steppers use when both are slewing the mount.  I have no idea what PSU is being used by the owner

I can have another look at the board, but unless we can get to the bottom of what blew the board again, then I fear we could be going round in circles and clocking up huge payments in postal charges in the process, with no result at the end.

Now I'm not saying this is the case here, but  the reason I document each repair in this thread (and via PM), including a video of the  board in operation is to cover myself against any accusation that I've ripped the owner off.  The video is proof that prior to leaving me the board was fully functional.  Also why would I want to rip anyone off?  I'm not that kind of person  and It would ruin my reputation on this forum, and my reputation means a lot to me.

I've yet to hear back form the owner if they have discovered what damaged the board once again.... nor if he has checked the power supply...  If he states the PSU is good, and that no other cable such as a USB/ Serial adapter rather than a proper EQDIR cable has been used then I'm at a loss as to how to proceed.

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Well I've not heard anything back form the owner of the blown board, and whilst I've shown that the original repair was successful, as a gesture of good will I have offered to undertake a second repair of the board at no charge (with the current silicon shortage the price and availability of the microcontrollers has meant a huge increase in prices). 

However I still feel that the issue the board keep blowing is down to something local to his mount, be that the use of a non standard EQDIR cable, power supply used, or the board is shorting on the casing in some way, and he needs to locate and identify that before using the repaired board if he accepts the offer of a second repair.

Other than that I can't really offer anything more.

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Pleased to say I've received further communications from the owner and having tried two different power supplies, and swapping the motors over, and flashing  the firmware (which proved that the PICs were OK and working ) he is getting no communication errors reported by the handset.  However one channel still has issues.  The stepper will commence spooling up, but then stall ( but sounds as if its running) when running at full speed, only to restart spinning when spooling down.  Swapping the motors proves the fault remains on that axis.  

It was noted though that the tubs the boards were packaged in were shattered despite being packed with foam sponges - so it would seem the parcel was treated with the Royal Mails  standard of care !!

The owner is considering claiming on the insurance (one reason why I insist on using special delivery), but in the meantime is going to return the kit back to me for inspection.  If I find the board is faulty, and I can replace any damaged or missing components I'll do my best to get the board up and running once more....

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Back in the day, when I had time, energy, enthusiasm and things were simpler, I did quite a lot of electronics repairs at cost for friends and family.

Tv, video, CB and radio gear, not to mention toasters and kettles (remember when they were worth repairing?). And it all got sour when people thought I offered a warranty on all future issues with that item.

I just stopped doing it. Now I have a tantrum if the MD just wants a picture hanging on the wall! 

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34 minutes ago, Paul M said:

Back in the day, when I had time, energy, enthusiasm and things were simpler, I did quite a lot of electronics repairs at cost for friends and family.

Tv, video, CB and radio gear, not to mention toasters and kettles (remember when they were worth repairing?). And it all got sour when people thought I offered a warranty on all future issues with that item.

I just stopped doing it. Now I have a tantrum if the MD just wants a picture hanging on the wall! 

Repairable toasters... yes I do remember the time, everything was mechanical back then.  I can remember my late mother laughing when adverts boasted about computer controlled toasters... "computers, just to make toast ! - whatever next?!"

When someone contacts me regarding a problem with a motor board it is made clear that I'm not a business, I offer no warranty or guarantee that I can fix the board, and clearly state that this is just an extension of a hobby.  It does frustrate me that relationship with fellow SGL members can be strained when after sending me a little cash to cover parts, time and return post by special delivery, and when the repaired board is received back the owner isn't happy as its not working.  It's not nice having to cover ones backside by having to take pictures and video of a 100% working repair, and the packed item to cover yourself.  However, now that it's been ascertained that the likely cause of the damage was due to the post office I feel somewhat relieved, but these experiences do make me question why I bother....

Anyway, as mentioned, the latest board is coming back again for me to have a look.  All I can do is order and replace parts to see if that fixes the problem.  Part of me feels like doing an unboxing, hooking it up to my supply and testing video prior to working on it.  If the motors run fine and is fully functional then I would be at a complete loss as to why it misbehaves when the owner sets it up.... despite reassurances that more then one power supply has been used. At least the original fault, that of "no response" for the RA axis has been resolved, so technically this is a new and separate repair that is being done at my expense !

 

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  • 3 weeks later...
8 minutes ago, AbsolutelyN said:

Not much info to go on but suggest you look here:
https://www.firstlightoptics.com/search/for/mother+board/

I've also had good experience from contacting Skywatcher direct but you'll need to give them much more info such as which product... 

http://www.opticalvision.co.uk/contact_ovl.html 

 

Thanks for the quick answer, but they do not have the synta mc004 board in stock (I saw a 4month delivery timeline from Skywatcher. I am looking for the actual component at the L4 location on the motherboard

 

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For which mount ? 

'L' usually denotes an inductor, so if you've passed enough current to burn one out, I'd also suspect that other components have also suffered some damage.

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MC004 is for a Dob mount. 

L3 an L4  are small surface mount ferrite beads that form a filter with two capacitors, possibly C8 and C9.  They are possibly BLM31PG500SN1L (or equivalent)  with the following spec:,

1206 [3216 Metric], 50 ohm, 3.5 A, EMIFIL BLM31P Series, 0.015 ohm

Available form most online suppliers (but most are affected by shortages due to CV19)

Having repaired several SW motor boards you may find that then two 16F886's have blown as well depending what you did to damage the board.  If you replace L1 / L2 and still get a "no response both axis" then you'll need to replace the PICs and have them programmed. as covered in this thread

EDIT - On HEQ5 / EQ6 boards L3 and L4 are Ferrite Beads - on the MC003 Schematic I have (similar to a MC004 for a Dobsonian) L4 is shown as an inductor....with no component value.  It connects pins 1 and 4 of the link cable connector to ground.  

Edited by malc-c
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9 hours ago, malc-c said:

MC004 is for a Dob mount. 

L3 an L4  are small surface mount ferrite beads that form a filter with two capacitors, possibly C8 and C9.  They are possibly BLM31PG500SN1L (or equivalent)  with the following spec:,

1206 [3216 Metric], 50 ohm, 3.5 A, EMIFIL BLM31P Series, 0.015 ohm

Available form most online suppliers (but most are affected by shortages due to CV19)

Having repaired several SW motor boards you may find that then two 16F886's have blown as well depending what you did to damage the board.  If you replace L1 / L2 and still get a "no response both axis" then you'll need to replace the PICs and have them programmed. as covered in this thread

EDIT - On HEQ5 / EQ6 boards L3 and L4 are Ferrite Beads - on the MC003 Schematic I have (similar to a MC004 for a Dobsonian) L4 is shown as an inductor....with no component value.  It connects pins 1 and 4 of the link cable connector to ground.  

Thanks Malcolm, was a long read and interesting, most of which I had forgotten when I was re-qualifying myself as a computer tech in Canada. Yes it is an Orion 16in dobsonian which had just bought. Are you still repairing these boards, if I send you our broken one?

Edited by chaotic-one
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On 13/10/2021 at 16:08, malc-c said:

I'll drop you a PM

Hi Malcolm and everyone else,

So as an WISP, we have plenty of old circuit boards laying around from radios we have built or that failed. On Friday I went painstakingly through the junk and found a board with labels F1, F2, F3, F4 on it. Pulled out the soldering iron yesterday and pulled off one of those "f-ing things" and installed it on my broken motherboard.

LAST NIGHT WE HAD OUR FIRST LIGHT ON OUR NEW-TO-US 16" DOBSONIAN.

Saw fuzzy Andromeda, looked at the moon, Pleiades, etc. It was a long night, cloudy and all.

NOW to spend the real money on eye-pieces. Thanks everyone.

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  • 3 weeks later...

Just received an update to the strange issues with the HEQ5 board covered on page 11 of this thread. 

To save you reading back, this was a board displaying the classic "no response" message and was repaired as normal.  A video was posted showing both axis working and the kit was repacked and returned, yet when it was received back the DEC motor would just vibrate rather than rotate.  Following further discussion I confirmed that the parts had been individually packed in foam and bubble wrap, and the board was also protected by wrapping in bubble wrap and placing it in a plastic container, which when placed in the box was intact.  However on receipt that box was in pieces...  Anyway as we had proof the board and motors were working when it left me, a claim was lodged with Royal mail (this is why I always use their insured special delivery service).

Well they paid up and  as a result the owner was able to purchase a new board and now has a fully working mount.

 

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On 18/10/2021 at 09:52, malc-c said:

Excellent.... nice easy fix !

Well Malcolm,

I putting the blame on you with your comment "nice easy fix". All was working fine until we tried to marry Asiair Pro to Synscan wifi adapter. On plugging in the "old" handheld it showed a message that it could not communicate with AR or AZ, making me think I have a new problem.

Any thoughts

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I'll keep quiet next time 👌 😄

Ok, so the board gets blown.... it seems the parts damaged are ferrite beads or zero ohm resistors.  You replace those parts form some other board and using the original handset re-established communications again and was able to use the scope.  But plugging in a wifi dongle and pairing it with the Asiair Pro fails...

  • When you do get the "no response" message with the handset then this suggests that either the components you replaces have again been blown (again), or the PICs are damaged and thus won't respond, and the culprit would seem to be the wifi dongle as this is the only hardware that was connected other than the handset.  If you have some more parts off a donor board then you could try replacing them again, and test again with the handset.  If replacing those parts again resolved the problem, then look at replacing the wifi dongle, or using an alternative method of control
  • If you were connecting form the Asiair via a hardwired option then possibly that may be the cause.  I've never had one so can't advise.

Bare in mind that these mounts were originally designed to use the handset as the means of control.  EQMOD and PC control via an EQDIR cable were all 3rd party development.  Now in theory the wifi dongle should mimic the same connections as the handset, so there should be no reason for the device to blow the ferrite beads (thus acting as fuses).  But it does seem strange that it was plugging that part in that has caused the communications failure once more.  Did you swap / plug the wifi dongle in with the mount powered up, or did you power up the mount with the dongle already in place ?

  

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10 hours ago, chaotic-one said:

Thanks for the input, wifi dongle was in and out when powered up a few times. My donor board has more ferrite beads, so will try your suggestion later.

Not really advisable to unplug and plug in things whist the mount is powered up to be honest... need to get in to the practice of park and power off when switching handsets and mounts 

lets hope swapping the ferrite beads resolves the problem

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On 04/11/2021 at 08:08, chaotic-one said:

Thanks for the input, wifi dongle was in and out when powered up a few times. My donor board has more ferrite beads, so will try your suggestion later.

 

On 04/11/2021 at 18:50, malc-c said:

Not really advisable to unplug and plug in things whist the mount is powered up to be honest... need to get in to the practice of park and power off when switching handsets and mounts 

lets hope swapping the ferrite beads resolves the problem

Okay replaced the ferrite beads, still no go, looks like I lost the programming on the chip maybe

 

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