LX90 PCB - good night, bad kit

[guff]

Hi all,

clear night at last but suddenly no motor. Dismantled base of LX90 and found blown pcb chip. I know I can buy a replacement pcb from the US (not an attractive prospect based on what I read) but has anyone repaired one of these pcbs? Chip marked '4947-L12B' and similar seems available on RS Components.

Long shot perhaps but I have two of these dud pcbs (one inherited) so might be a common happening - and fix?

cheers

Geoff

[guff]

Sorry... picture thing did not go so well...

G

[ChrisLX200]

Problem is that circuit is unlikely to have spontaneously destroyed itself, you'll have to trace back to a power component or something that was the source - a capacitor, resistor, diode, connector or similar. It might quite distant from this failed chip.

ChrisH

[guff]

Good point. Looking for ways to avoid spending £ really, clutching at the straw that the motor took it out  - not used for five years before being given to me - thanks Col. Worked for a couple of weeks then pop.

Will buy new, but not give up on restoring some spares too.

cheers

G

[michael8554]

Some spare parts are now available from Meade UK.

As ChrisLX200 said, you need to find what caused it to blow.

What voltage is your Power Supply putting out? Should be no more than 12 to 14V - not using an 18V Classic LX200 PSU by any chance?

Do you have a 2.5Amp quick-blow fuse on the 12V line, this might blow before your board does !

Is the scope badly balanced, long-shot that too much load might be the problem.

Michael 

[guff]

Thanks for the checklist Michaei - car battery,  no fuse (then) and balance has admittedly been a little variable on occasion. Early days for me, if not the scope. Hopefully other lessons will not be so expensive. 

cheers

Geoff