Well, I was searching on Richard Shuford's wonderful website about
video terminals, and I came across a bit of useful information.
Apparently the power supplies and picture tubes are interchangeable
between Televideo 910, 910+, 912, 912C, 920, 925 and 950 terminals. I
had a 950 in the basement with a power supply problem, so I pulled the
logic board out and stuck it in the 912, and connected the 950's
external keyboard. It worked perfectly. This means there is something
wrong with the 912 logic board. I closely inspected the 912 board,
cleaned the dust off and reseated the socketed chips (the EPROM chip
seemed to have some bent pins), but it didn't help. I noticed that the
912 board appears to have been modified. One or two things look like
factory changes. The others look home hacked. Here are the changes that
I can see:
Those that look factory made:
Green jumper wires on the bottom are connected between:
Pin 1 and 4 of chip A77, an LS74
Pin 4 of chip A28, an LS74, and pin 8 of A44, an LS04
Pin 9 of A44, an LS04, and Pin and a solder point to the right of A51
Those that look home hacked:
Cut traces on the top
W8
Pin 11 of A77, an LS74 and Pin 3 of A28, an LS74
W28
W26
W6 seems to have a clumsy looking scrap of wire bridging it.
W31, W32, W33, W34 look as if something was desoldered between all four
The printer port seems to have been replaced or removed at time,
judging from the brownish colored solder joints. The same goes for the
S3 (printer baud rate) dip switch block.
There are four white empty 18 pin DIP sockets on the right hand side of
the board (RAM upgrade option?)
There may be other modifications, but that was all I could find.
Any ideas? Was this some upgrade, or was there supposed to be another
module with this?
Thanks!
Ian Primus
ian_primus(a)yahoo.com
On Friday, October 25, 2002, at 06:29 PM, Sark wrote:
I just got a Televideo 912 from an ebay auction. It
seems to work
fine, it feeps, and a cursor appears in the upper left. I have tried
to connect it to my Linux computer in place of my regular terminal (a
DEC VT100),and it didn't work. I noticed that after the terminal had
been on for a minute or so, the cursor disapears from the screen,
regardless of wether it was connected to the computer or not. Then, if
I turn it off and on again, the cursor reappears, and then goes away
again. I have tried setting the baud rate, etc. according to the
manual I downloaded from
vt100.net. Any suggestions? I really want to
get this terminal working.
Thanks!
Ian Primus
ian_primus(a)yahoo.com