Welcome, Guest. Please login or register.

Username: Password:

Author Topic: Direction reversing at random  (Read 3010 times)

almcl

  • Full Member
  • ***
  • Posts: 25
    • View Profile
Direction reversing at random
« on: August 09, 2016, 22:50:30 »

After months of faultless performance and a particulsrly successful Messier hunt yesterday night out at a dark sky site, a weird problem has arisen.

Tonight, as I attempted to use the newly acquired gamepad to nudge Vega into the centre of the FOV, the West button in Eqmod suddenly reversed direction so it and the east button now both moved the mount in the same direction.  This happened randomly sometimes reversing again after a few presses and it seemed some very large movements (sufficient to move it two fields of view out of the finder scope) also occurred.  The only thing I have changed (that I am aware of)  was the RA cable where  a longer one was substituted in an attempt to 'tidy up' the birds nest of wires.

Could a faulty cable cause an issue like this?

I'll swap it back tomorrow but any thoughts would be most welcome in the meantime.
Logged

TCWORLD

  • Administrator
  • *****
  • Posts: 751
    • View Profile
    • AstroEQ
Re: Direction reversing at random
« Reply #1 on: August 11, 2016, 23:29:14 »

Does the issue still occur when you don't use the gamepad?

If it does, then one possibility could be a bad connection on the RA direction pin. It's possible if there has been dew build up or something the contacts in the IC socket could have oxidised, but I wouldn't have thought so. Alternatively a cold solder joint that has finally broken free could be a culprit (if it was loose and the box took a knock it could break the connection).

Have you upgraded any software (e.g. EQMOD or the AstroEQ firmware) at any point between it working and not?

Also, what settings are you using for the mount, and which firmware/EQMOD version (so I can try to recreate the problem).

Tom.
Logged
Tom Carpenter (AstroEQ)

almcl

  • Full Member
  • ***
  • Posts: 25
    • View Profile
Re: Direction reversing at random
« Reply #2 on: August 12, 2016, 18:25:34 »

Hi Tom,

No upgrades to Eqmod or Astroeq.  Version 7.4 firmware.

Settings imaged below.  The controller did take a fall to the concrete floor and the USB diode no longer works (I found it had fractured when I opened the case) so I think a damaged unit is very likely.  I emailed you separately about that with a link to dropbox video before I noticed that you won't have anymore time till October, sorry!

Weirdly, Dec still works perfectly normally but while I have now got RA to slew at full speed (800), before it starts the full speed bit, (during the slow speed start up) it oscillates back and forth and I suspect won't track for the same reason.

I suspected the game pad, too, so all tests since the first event have been with it disconnected.



Logged

TCWORLD

  • Administrator
  • *****
  • Posts: 751
    • View Profile
    • AstroEQ
Re: Direction reversing at random
« Reply #3 on: August 12, 2016, 18:45:11 »

I would try pulling the RA motor driver board out and reinserting it. Perhaps also do the same with the ATMega. This will make sure there are no loose connections as a result of the fall.

It's also possible that if the diode broke that it could have done damage to one of the two crystals which are also relatively fragile. But I would start with the easy things - reinsert the ICs, and check for any loose solder joints (you can always take a hi-res photo of the back of the board if you want me to have a look.
Logged
Tom Carpenter (AstroEQ)

almcl

  • Full Member
  • ***
  • Posts: 25
    • View Profile
Re: Direction reversing at random
« Reply #4 on: August 12, 2016, 20:03:09 »

Thank you, Tom.

here are a couple of jpegs on which you can see my largely unsuccessful attempts to de-solder the damaged LED.

Anything jump out at you?

I've tried unseating and reseating the driver board (getting quite good at this now) with no improvement, but haven't summoned the courage to apply sufficient force to the main chip - it seems very well tied down?
Logged

ultramol

  • Jr. Member
  • **
  • Posts: 9
    • View Profile
Re: Direction reversing at random
« Reply #5 on: August 12, 2016, 21:37:26 »

If it is a wireless gamepad dont now if this will help. I had similar problems and it was the gamepad shorting and sticking on the paddle. Binned it and got another and now it is fine.
Logged

almcl

  • Full Member
  • ***
  • Posts: 25
    • View Profile
Re: Direction reversing at random
« Reply #6 on: August 12, 2016, 22:54:48 »

Thanks for the thought, ultramol. 

Unfortunately it's a wired gamepad and although it may well be implicated in the original failure, it has been disconnected for the last two days but the fault persists.
Logged

TCWORLD

  • Administrator
  • *****
  • Posts: 751
    • View Profile
    • AstroEQ
Re: Direction reversing at random
« Reply #7 on: August 17, 2016, 15:59:26 »

I'd try applying a bit of heat with a soldering iron to pin 20 of the main IC, just to make sure there is a solid connection (it doesn't look quite right).

Beyond that, I don't see a hardware issue.

If you want to try reinserting the main IC, what you need to do is feed a small flat head screw driver in from the end of the IC between the IC and the socket. If you slowly do that, bit by bit from each end both it should work its way free. If you put your finger gently on the top of the IC while doing it, it should prevent it popping out and bending pins.

You could try the beta firmware from the beta section of this forum, but I doubt it would solve the problem.
Logged
Tom Carpenter (AstroEQ)

almcl

  • Full Member
  • ***
  • Posts: 25
    • View Profile
Re: Direction reversing at random
« Reply #8 on: August 18, 2016, 07:51:28 »

Thanks for that, Tom.

Somehow, in the course of multiple re-configurations, several cable swaps and changes, re-seating of components &c, it's working again!

I'll hang back on the LED replacement and re-soldering for the moment (my 12 watt soldering iron couldn't melt the solder on the LED pins enough to extract them) until the next self inflicted event! 

The Astroeq is now firmly secured to the mount to prevent further contact with the concrete floor!
Logged

TCWORLD

  • Administrator
  • *****
  • Posts: 751
    • View Profile
    • AstroEQ
Re: Direction reversing at random
« Reply #9 on: August 18, 2016, 16:41:46 »

Glad it is sorted. It's entirely possible that the drop may have shaken something loose and you've managed to reseat it.

I'll admit, I haven't done any testing involving gravity and/or a concrete floor, so it's nice to see that they can keep going after such a fall.

Tom.
Logged
Tom Carpenter (AstroEQ)