Sunday, June 8, 2025

Wrapping up testing of 2501 card reader power supply box - one bad component discovered

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INVESTIGATED THEORY ON HOW TRANSFORMER PRIMARIES ARE CONNECTED My speculation on how the US transformer might be connected to the five termi...

More on differences between US and European versions of 2501 card reader (model A1/A2) power supply

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THE OBVIOUS FIRST The mains voltage and frequency are different between the two geographies, which leads to the need to change the transform...

Power supply out on bench and partially restored so far

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DISCONNECTED MOTORWIRING AND ONE REMAINING WIRE The wiring to the motor was hooked up on a terminal block on the top compartment of the mach...
Saturday, June 7, 2025

Received scan of 2501 card reader logic diagrams and wiring schematics

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ASSISTANCE RECEIVED (ONCE AGAIN) FROM A EUROPEAN MUSEUM A museum that has successfully restored a 2501 as part of an IBM 1130 system did hav...
Thursday, June 5, 2025

Disconnecting wiring to remove power supply box from 2501 card reader

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WOULD BE VERY INCONVENIENT TO TEST PS WHILE INSTALLED UNDER READER The power supply and power control box sits in the bottom cabinet of the ...
Sunday, June 1, 2025

Cleaning up the acrylic cover for the 1053 console printer and identifying another issue

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COVER FOR 1053 The cover over the IBM Selectric typewriter mechanism that is the console printer for the 1130 computer has an acrylic cover ...

Various fixes to the IBM 2501 card reader and inspection of lower cabinet circuitry

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STACKER GEAR A TOUCH TOO SMALL TO ENGAGE FULLY The stacker mechanism that collects cards after they have been read uses an oscillating part ...