13 Feb
2006
13 Feb
'06
3:35 p.m.
David Griffith wrote:
I'm trying to restore an Osborne Executive, but there seems to be
something wrong in the CRT circuitry. The machine powers up and beeps,
but I see nothing on the CRT. Fiddling with the CRT pots does nothing.
I hear none of the expected noises from the CRT circuitry, nor do I see or
smell anything burnt. Can someone here point me in the right direction?
--
David Griffith
dgriffi at cs.csubak.edu
Check the composite video out at the RCA jack on the front
panel. The same signals drive two buffer ICs, the composite
comes through U22 and the internal CRT drive comes through u7.
There needs to be a jumper plug on the external CRT edge
connector, beside the RCA jack, in case yours is missing. That
jumpers the CRT drive signals back into the internal monitor.
John