Osborne One -- No video

From: Rich Beaudry <r_beaudry_at_hotmail.com>
Date: Wed Jul 18 09:40:46 2001

{sorry for the delays in replying, but I only get the digest}

Ok... I broke out the meter, and did a few checks....

Tony Duell suggested:

>That's a nice, simple, circuit to start with. Carefully pull the
>connector off the base of the CRT and check the heater continuity. If it
>is a 7 pin CRT, it's a fair bet the heater pins are numbers 3 and 4.

Well, it was a 7-pin connector, and I put an ohmmeter across pins 3 and 4.
It measured 31.7 ohms. Is that reasonable?

Robert Feldman suggested:

>First thing to check is to make sure that you are getting +12V on contac1
14
>of the circuit board and pin 7 of the inline connector.

I am getting +12V at both of these points (And by the way, thanks for the
pinouts and other information!!)...

Also, I suspect what I am referring to as a composite video output may not
be that at all... It is an RCA jack that is attached to the front of the
case, and is located just to the right of the connector marked "Battery".
It has two wires attached, which go to a 2-pin plug on an "L" shaped circuit
board. The "L" shaped board also contains the Z-80, some 6116 chips, and
other stuff. It also contains the inline connector that Robert gave the
pinout for (and in fact, the 2-pin plug is in very close physical proximity
to the inline connector). I have seen several pictures of Osbornes, and now
that I review them, none have this connector. It does not seem to be a
hacked on modification, since the plug on the "L" shaped board was very
obviously factory done.

I will take Tony's advice and trace back to see if and where the 12V fails.

Thanks!

Rich B.
Received on Wed Jul 18 2001 - 09:40:46 BST