Soemtron ETR Calculator Spare Parts

Stress fractures in a keyboard guide plate, click image for a larger version. ©2011
Age related stress fractures
(Click any image for a larger version)
We have rebuilt her! - the refurbished unit, click image for a larger version
3D printed Soemtron ETR220/222
Cabinet latches (right & left handed)
Right hand 3D printed cabinet latch, click image for a larger version
Assembled 3D printed
Soemtron ETR220/222 latch

Plastic parts for the Soemtron ETR range of calculators are now around 60 years old and have reached their end of life and become extremely brittle, none more so than the cabinet latches that hold the two-part covers to the main chassis, these seem to be the first items to break when the cabinet is opened.  These mouldings were used in various places (E.g. Decimal point and mains switch knobs, card cage end plates) and do seem to have been quite well made in most instances, but many years on since their manufacture they have become prone to sudden age related disintegration.  Some items, like the keyboard buttons guide plate suffer from stress fractures whilst not actually falling apart (right, first image).

We can offer a low cost 3D design service to generate the STL format files needed so that you can print your own replacements, us with your requirements.  So to prove the process we started with the cabinet latches, of which we have had multiple failures, we produced a design and had them 3D printed.  These are direct drop-in replacements for the original latch parts in the ETR220 and 222 units and require no modifications to fit, simply unscrew the old broken latch and swap with these new parts.  We have stock to hand so for price and delivery contact us, or email us .

We also have stocks of these Soemtron items

  1. Brand new unused Z570M display nixie tubes (DP pin 4?), P# 00–560–9558–3,  data.
  2. Brand new unused Z573M display nixie tube (DP pin 10?),  data.
  3. Reclaimed keyboard switches with the correctly formed PCB solder pins (type C11) for direct replacement, P# 00–803–024–8.  Originally these switches were thought to be a V23 microswitch variant, however the correct style is the ABB or Petercem, M & CM style switches (data sheets ABB, Petercem), but with right angle PCB pins.  Data for these particular right angle PCB mount switches however, does not seem to be available even though they are from the M/CM range.
  4. Reclaimed microswitches (type C2 & C3) for the Mains On/Off switch, P# 00–803–005–5.  See the ABB and Petercem switch data above.  The keyboard switches are the same style, but they do not have the right angle PCB solder terminals.  With a couple of wire links these could also be used in place of the standard C11 type keyboard switches above.
  5. A new equivalent part (TC290) for the original power supply mains input filter which often "leaks" its contents and then destroys itself, P# 00–422–182–4,  data.
  6. New 3D printed cabinet latches in left (05–220–3023–7) and right (05–20–3024–5) hand variants.  (2nd photo above right).
  7. A complete ETR220 keyboard assembly, but missing a connector and part wiring loom (replaceable), P# 20–220–1097–7.
  8. 31 pin board to backplane connectors, supplied as a pair (1 R/A board plug & 1 backplane socket).

ETR220 PCB board assemblies (issue) -

  1. 3(5c) - Board 3 - Arithmetic unit A Register, digit drives 5–9.  Date coded [wk/yr], marked 05-220-7003-5 (5c)
  2. 4(30i) - Board 4 - Arithmetic unit E Register, Carry latch and digit drives 0/1.  Date coded [wk/yr], marked 05-220-7004-3 (30i)
  3. 5(1h) - Board 5 - V, SCHREIB, S1 function latches and 25Khz clock.  Date coded [wk/yr], marked 05-220-7005 (1h)
  4. 6(?) - Board 6 - Control gating.  Date coded [wk/yr], marked 05-220-7006-8 (?)
  5. 7(A) - Board 7 - B1–4, VOR and R function latches.  Date coded [wk/yr], marked 05-220-7007-6 (A)
  6. 7(C) - Board 7 - B1–4, VOR and R function latches.  This board has evidence of some rework.  Date coded [wk/yr], marked 05-220-7007-6 (C)
  7. 8(D) - Board 8 - F1, F3, VER and MZ function latches.  Date coded [wk/yr], marked 05-220-7008-4 (D)
  8. 10(B) - Board 10 - 5 bit address "Z" counter.  Date coded [wk/yr], P# 3042 05-220-7010-7 (B)
  9. 12(30f) - Board 12 - Display Cathode Drivers, numeric key encoding.  Date coded [wk/yr], P# 05-220-7012-3 30f

Again for price and delivery for any of our spares contact us, or email us for prices and shipping costs.

Part number list - a list of all Soemtron part numbers currently available to us from various documents (35Kb)

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