On Mon, 10 Jun 2002, Ethan Dicks wrote:
> A follow-up: Looking at the notes on the "IBM Wiring Diagram",
> number 228005-5, E.C. #203242, "Machine - Printing Card Punch,
> Model 026" which I found in the base of mine, there are notes
> on the 4th leaf (it's one long folded sheet) in Roman Numerals:
>
> X All tubes are 25L6's
> XI All bias resistors are 56K, .5W, part no. 301149
> All screen resistors are 4.7K, 1W, part no 169129 unless
> otherwise noted
> All grid protection resistors are 10K, 1W part no 184093
> XII Tube #8 and relay 53 are used only on machines with
> comb. keyboards
> XIII ----- - - ------ indicates wiring when comb. keyboard used
> XIV -- -- -- -- -- indicates wiring when num. keyboard used
> XV =====o===== indicates solid bar common
> XVI The marked NC terminal on the switch is the terminal
> wired as shown
> XVII Resistor common not wired as shown
>
>
> A couple of things: it explicitly says all tubes are "25L6" and that
> only tube 8 is optional, depending on configuration. From looking
What is the "comb. keyboard"? Combination? At any rate, maybe I can move
tube #8 into the #6 position and play around with it in that configuration
and see what happens.
> at the rest of the wiring chart, I can see all the tubes in use
> except for 6, the one that Sellam seems to be missing. The tubes
> seem to drive various relays thusly:
>
> 1 Escape Interlock
> 2 Release(?)
> 3 Escape Magnet
> 4 Skip
> 5 Dup
> 6 ?
> 7 Punch Clutch
> 8 Alpha Field (with comb. keyboard)
> 9 Print Sup Magnet
> 10 Print
>
> No mention of tube 6. :-(
Bummer. But that is some very solid information. Thanks for posting it.
I should finally have time to track down that tube and replace it this
week.
Sellam Ismail Vintage Computer Festival
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Received on Mon Jun 10 2002 - 15:27:45 BST