Osbourne 1 problems

From: Sark <ian_primus_at_yahoo.com>
Date: Tue Oct 15 20:30:01 2002

Oh, also, does anyone have the schematics for the composite adapter, or
someplace where I can find one? I have heard rumors of an electronics
store on the 'net that still carries them.

Thanks!

Ian Primus
ian_primus_at_yahoo.com

On Monday, October 14, 2002, at 05:56 PM, Feldman, Robert wrote:

> I have an O1 Tech Ref manual, from which I can send you info that
> might be
> useful. I'm busy this week, so won't be until next, though.
>
> One thing to check is the video shunt on the front of the unit. It
> takes the
> video signals and power from the bottom of the board and passes them
> to the
> top, where they go to the monitor. If the contacts on the shunt are
> oxidized, you could have video problems.
>
> The pinout of the edge connector is (numbered right to left, odd on
> top,
> even on bottom):
>
> (19 ... 1)
> (20 ... 2)
>
> 2 Ground
> 4 Brightness High ---> 3 on top
> 6 Brightness Low ---> 5 on top
> 8 Brightness Arm ---> 7 on top
> 10 Ground
> 12 Horiz Sync
> 14 +12 volts
> 16 Video Out
> 18 Vert Sync
> 20 Ground
>
> 3 and 7 go to the outsides of a 100K brightness pot, 5 to the wiper of
> the
> pot.
>
> Video out and one of the grounds go to a 500 ohm contrast pot.
>
> Bob
>
> -----Original Message-----
> From: Sark [mailto:ian_primus_at_yahoo.com]
> Sent: Monday, October 14, 2002 2:08 PM
> To: cctech_at_classiccmp.org
> Subject: Osbourne 1 problems
>
>
> I recently accquired an Osbourne 1 computer. I turned it on and it
> seemed to work, I was able to boot BASIC off of a floppy and I wrote a
> couple little programs, (print hello world, count to ten, and count
> forever, stuff like that). The picture on the screen was kinda dark in
> spots, and while the computer was counting, it flickered to a very dark
> and barely readable, then it went black all together. I tried turning
> up the brightness and contrast controls, the only one that makes any
> change on the screen is the brightness control. I can see the rasters
> when the brightness is up all the way, but the contrast control has no
> effect. The computer seems to still work though, I can turn it on, then
> hit enter and it will boot from the floppy. Previously, when it was
> working, I noticed the screen flicker when the computer accessed the
> floppy drive. My guess is that there is something wrong with the power
> supply. Does anyone have any ideas? I would really like to get my
> Osbourne working again, it's a really cool little computer.
>
> Thanks!
>
> Ian Primus
> ian_primus_at_yahoo.com
>
Received on Tue Oct 15 2002 - 20:30:01 BST