Graham,

Based on the symptoms, it sounds like your motor driver has blown. These
typically are a circuit usually called an H bridge with the motor as the
cross bar and transistors as the four vertical arms. Going one way, current
through the H will flow Northwest to Southeast, while for reverse direction,
current would flow from Northeast to Southwest, reversing the sirection of
current through the motor. So what seems to have happened is that one of the
four transistors was blown out - the motor would then move in one direction
and not the other. So, you need to determine which IC is the motor driver
and repair it. Note: it may be a dual motor driver with two complete
H-bridges. The part probably costs less than $5.

Someone on this list who has opened up their LX-200GPS can probeably tell
you the exact part number and where to find it on the circuit board.

Randy Marsden



----- Original Message -----
Sent: Wednesday, October 06, 2004 1:59 AM
Subject: [M]: LX200 RA motor stalled in East direction?


> I've searched the archive but cannot find this odd one
>
> I have a 12" GPS system which has worked perfectly until last week when
the
> dew heater control (BC&F) pulled from its fork arm velcro and landed on
the
> wedge (permanent metal pier into ground) and I guess there was an earth
from
> the tape connector part as a nice tiny blue spark popped and the dew
heater
> failed. At the time both the LX and the dew controller were running off
the
> same 12V battery supply.
>
> From that point the LX complained that the RA motor had stalled whenever
an
> "East" motion was required and although N,S and W work from the key pad I
> have no joy with E (rightmost key) it just moaned that the motor had
> stalled.
>
> I replaced the fuse on the dew controller (2Amp) and gave it its own
battery
> (it works fine) and recharged the one for the LX - (in case it was the
> poorly charged battery trick).
> To no avail.
> Now I can turn on the scope go through the polar one star align and the
> motors slew to Polaris (so good so far) but after I adjust the mount and
> press enter - I get the message "motor stalled" this is most frustrating
as
> I have W but no East.
> I can only assume that this is 99.9 % going to be an electrical problem
> given the fuse blowing coincidental timing.
>
> I don't have a problem having a poke in the guts of it but I have no idea
> where to start - does anybody have any ideas?
>
> Graham McPherson
> UK
>
>

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