Replacement tube for IBM 026 Printing Card Punch

From: Ethan Dicks <erd_6502_at_yahoo.com>
Date: Mon Jun 10 13:54:47 2002

--- John Lawson <jpl15_at_panix.com> wrote:
> Hey Ethan, this is cool!
>
> While there has been a great deal of sage advice, speculation,
> maybes, and 'try this' posts concerning the 026 - yours is the first
> positive lead.

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
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. :-(

-ethan



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Received on Mon Jun 10 2002 - 13:54:47 BST

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