On Wed, 28 May 2003 11:29:37 +0100, you wrote:

>I have an HP 7475A plotter (GPIB interface that seems to have a =
temperature
>based fault. I have done some digging around on search engines looking =
for a
>circuit, but have come up blank so far.
>
>The problem is that it seems to loose track of pen position, or else =
senses
>motor overcurrent on (presumably) the X axis. It is never consistent in =
when
>the error occurs which also leads me to believe it is a temperature =
fault.
>The motors appear to be DC ones with a quadrature optical encoder, so =
the
>fault could be one output of an encoder, but the machine does not run =
for
>very long before failing, making it almost impossible to service without
>some circuit info.
>
>The alternative is to come up with some GPIB to serial converter that we=
 can
>use to get hard copy of an instrument (an HP 3562A Dynamic Signal =
Analyser)
>which has no other means of data access (Yeah, I know - great project =
for a
>PIC!!).
>
>any help appreciated.

=46or tracing temp-related  faults, a hairdryer and can of freezer spray =
is invaluable.

Might make life easier if you can drive it from a PC to put  into a fixed=
 motion pattern.=20

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