S100 Buss extender boards

[Randy McLaughlin]

From: "Richard A. Cini" <rcini at optonline.net>
Sent: Sunday, June 05, 2005 2:46 PM


> All:
>
> Part of the goodies that came with my IMSAI was a buss extender
> board which has a logic probe on it, which I definitely use for
> troubleshooting this stuck bit problem. One of the transistors on the 
> board
> has a lead that's broken at the case.
>
> The designation on the transistor is "F444". There's a second
> transistor marked "F137" which also seems to have shakey leads.  The board
> is manufactured by Mullen Computer Boards, model TB-1.
>
> Can anyone cross these numbers to a current replacement? Googling
> has come up with a possibility for the F444 but nothing for the F137.
>
> Thanks.
>
> Rich
>
> Rich Cini
> Collector of classic computers
> Build Master for the Altair32 Emulation Project
> Web site: http://highgate.comm.sfu.ca/~rcini/classiccmp/
> /************************************************************/

I have a couple, I'll see if they use different transistors.  It's a simple 
probe and just saturates the transistors.  I would guess that they can be 
replaces with any general purpose switching transistors as long as you match 
up PNP or NPN (2n2222 & 2n2907 ar my favorites).

If I either of mine use different transistors I'll follow up.

I like the fact that the power lines can be isolated so it's easy to test 
for voltage/amperage etc.


Randy
www.s100-manuals.com