Debugging the card reader is tricky. The card reader...

Debugging the card reader is tricky. The card reader is controlled by numerous relays, electromechanical switches that are prone to malfunctioning if their switch contacts get dirty. The photo shows rows of relays above a jumble of diodes and resistors. 2/8

Like 3 May at 16:27 | Open on oldbytes.space

4 comments

Ken Shirriff

To debug the relay circuits, I built a Hall-effect sensor to magnetically determine if the relay was activated or not. https://twitter.com/Curious_marc helped me build the sensor and mounted it in a stylish soap dish. The sensor displays the relay status over time on the oscilloscope. 3/8

3 May at 16:27 | Open on oldbytes.space

Paul Evans

@kenshirriff I have the same 'scope as this, though my hardware lab is missing a soap dish at all, let alone one as stylish as yours. Clearly I shall need to correct this oversight.

3 May at 17:46 | Open on fosstodon.org

Tor Lillqvist

@kenshirriff Oh my. Is this how professional electronic equipment looked on the inside in those days? Such haphazard assembly of components.

24 June at 16:35 | Open on urbanists.social

int%rmitt]nt sig^al. ...~!...)

@kenshirriff
Oh kryst, minds me of a main console card reader of an IBM370-135 that I was running in 1974 or so that went tits up in the middle of 1st shift spewing smoke annaw. Took the men in black about 20 hours to sort it.

24 June at 16:40 | Open on mastodon.social

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