Losmandy Digital Drive - short circuiting

[Kal]

I set up on Wednesday night, only to blow the fuse from the cable out of my powertank as soon as I switched on my G11 digital drive system. After locating another fuse I put it in and it blew straight away again.

After troubleshooting the problem today, I found out that the short was coming from a part of the circuitry in the top right hand corner of the unit, on the rear side of the PCB. The circuitry there is positive, not ground, and it was shorting to the case where the corner screw attaches. Strange that this problem is not more common considering the layout (or maybe the design changed later? I have a pretty old 1998 model).

A bit of electrical tape to prevent the short and it all looks good now.

[JohnG]

I vaguely remember this problem coming up in the late 90's on the Losmandy Group, if I remember clearly it was to do with the drive box attachment bolt going too far into the drive box and pushing against the PCB.

I think the suggestion was at the time to put a washer on the attachment bolt and reset the PCB holding screw.

Haven't heard of this problem for years.

Cheers

[[1ponders]]

John has got it. I had a new switch put into mine and the tech that did it said at the time to be careful not to tighten those screws or to washer under them for exactly that reason.

[Kal]

Funny you should mention that Paul. When troubleshooting it at work today I couldn't replicate the problem, probably because I had pulled the front panel off and in turn loosened the mounting screws. After half an hour of fiddling and conceding it must have been dew or some other variable, I tightened the four screws and put the cover on, and immediately short circuited it. This at least gave me the hint of where too look for the problem.

Strange how I have had this mount now for 18 months or so, used it on maybe 20 odd occasions, and just now this problem surfaced.