Not a thread on how to avoid being a crispy critter yourself
A couple of times this year I have had PC re-starts, several significant enough to temporarily (thank goodness) kerblitz the telescope hand controller.
I found this surprising to say the least as I was running mains power, through a modern (electro active circuit breakers) power board in the house, into a Uninterruptible Power Supply (UPS) into my PC, Cameras and mount.
Worst case twice a day things might instantly re-boot with no warning signs. Twice this had affected the hand controller required a hard re-boot.
I initially thought it was a PC problem, possibly down to gear shorting or a blown capacity (groan), but after a bit of wiring to the house required a total power off re-start – I realised my UPS wouldn’t cold boot from mains – indicating the battery or internal electronics weren’t up to scratch.
Rather than expose expensive gear to electrical zaps I relaced the UPS – and all is fine since then. But now I am going one better – surge protectors on the serial ports (signal and guide port connectors).
For about $60 a unit you can isolate and protect your mount from whoopsies on your PC. A serial port by definition should never generate voltages in excess of +/- 25 volts - so at 26 volts plus you should cap the current.
This is pretty easy to do with 20 mega ohm Zennor Diodes or Varistors or Optic Couples. I found Unitech Electronics in St Andrews Sydney makes a Zenner Diode version which with freighting comes to $60 a unit. Basically a 9 pin serial port has 8 live pins and a ground pin. They supply a unit that goes onto the back of your PC that your serial cables simply plugs into. This unit has an external Earth wire you have to physically ground (think a length of thick Earth wire attached to this lead and going back into a metre and a half of 1/2 inch copper pipe hammered into moist soil).
The point to all this is if you operate off batteries with or without a line conditioner – life will mostly be good unless a battery shorts the wrong way. Operate off mains and every now and then the mains grid might throw something at you that your uber-expensive gear doesn’t like! The easiest way to minimise risk is electrical protection provided by surge protectors and UPS’s. However one extra bit of insurance is serial port surge zappers – from now on all my expensive gear will have this little bit of extra protection!
