jimboozle

Hi Lumos, The problem was that I hadn't pulled my finger out and fitted the anderson connectors. Instead I was powering directly from a bench mounted 12V supply, and I got the polarity wrong. Now the powerpoles are in place, it won't be happening again! The mount has a standard 5.5 x 2.1 mm DC jack input, with the tip positive. It's pretty hard to get it wrong, but these things happen!

I might have gone overboard labelling, but I’m not having this happen again! I’ve velcroed the board to the mount so I can transfer it to my big setup when I eventually get the RASA collimated again… Cable management to follow, I promise!

Thanks for the info! I’ll try some of those suggestions when I’ve finished work. Looking at the 2171 it does look a little discoloured, which could well be due to it cooking. as previously mentioned, I’m awaiting a new board so this isn’t top of the list, but I’d like to get it running mainly out of interest, and to keep as a spare I guess. thank you for taking the time to reply, and I’ll update you all on progress once the slow boat from china brings my 7805. in the meantime, a hefty diode is now across the power input so it doesn’t happen again, and an Anderson connector based 12v distribution board is in construction…

Thanks for the tips - I'll have a look at U1, it sounds like a very likely culprit. Thankfully my replacement will be here in a day or two, but I'd like to get this going as a spare, and I will DEFINITELY get a diode attached! Great idea, and no idea why Skywatcher don't spend the extra 20p doing so...

Thanks for the tip Keith - on your advice I've just tried that. All is ok if I just power up the power board (well, nothing happens, and the power supply is happy to stay running). Connecting it to the control board (only) causes the power supply to cut out, hence my thinking there is a short early on in the control board power circuitry. I guess I'm going to have to follow the power circuit through the board and find out where it stops, using my trusty old multimeter only. It's going to be a fun evening!

well, it wasn't those two capacitors. Both replaced with comparable parts but no dice. I have noticed that when I connect the power supply, it cuts out, indicating a short circuit. It's evidently downstream of C41 and C3. Any ideas?

Yep, you've guessed it! Fumbling around in the dark and I got the polarity wrong. You never think you are going to be that person, until you are... I've fixed the cause of the issue by upgrading my power supply this morning - stable door after the horse and all that. Rather annoying since I haven't used the kit for a couple of years, and am rekindling my interest following a fascinating day at PAS2023. Anyway, I digress. It's pretty hard to faultfind the board properly, as i sold my handset years ago, relying on a Lynx Astro cable for communications. Which was fine until it wasn't. ASCOM now rather predicatably has a comms error with the mount. However, now it's broken, obviously i'm not getting comms with the mount, and the power LED doesn't light up, which from what I've read is a clue. I've stripped down the mount and have the input board and control board on my bench, and I'm tracing the power through the system - I found an old thread where @malc-c went through this same saga - your posts were fascinating and awfully helpful, thank you. In particular, i've inspected the two 470uF capacitors - they look ok, but I'll dig through my spares box and see if I can find some since I've probably got some lying about. I've checked conductivity across all the resistors and inductors, and everything seems fine, so far. Except obviously it isn't! I've got another board on order, as it's been twenty years since my electronics degree, so i'm not too hopeful, but I'd love to fix this one if I can. My plan: Replace the two big capacitors (C41 and C3, by Jumper 1) See if it works (unlikely!). Any other likely culprits to hit next? A schematic would be useful if anyone knows where to find one, so I can trace the power through the board until it stops... Thanks, Jim

did you get it working with SGP? I'm now highly tempted to use the arduino I was given a while ago to add motor focus to my WO66. I've got a moonlite on the 120ED, but not willing to shell out for another 'real' focuser...

I have an unopened set of 36mm Baader LRGB filters £240ish, and may even part with a flocked and blackened 200PDS, probably around the standard 200quid mark. If I can be persuaded to sell the scope, I've got a telrad, an Orion SSAG and 50mm guide scope, and a Baader MPCC I'll not use again. Afraid I've joined the frac revolution... dunno where my pitch is, but I'm there fri-sun - update, I'm on Hare 60

Your composite picture idea from the book is playing no small part in my charm offensive on my long haired general! Might wait for the next house move though as a little close to Birmingham at present