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Tube❄️Time

being electromechanical, it's full of a lot of relays, steppers, and other such mechanisms.

the schematic is a classic example of "ladder logic." the sides of the ladder are the power rails (in this case, 24VAC) and the "rungs" are individual control circuits, typically a relay coil on the left and a set of contacts on the right that, when properly engaged, turn on that relay.

7 comments
SLeiBt

@tubetime Around the turn of the century/millennium, "ladder logic language" was the usual form of programming tool provided by PLC manufacturers. Inputs on one side, outputs on the other.

JeffG

@tubetime I have one in the garage I want to get going, a Bally X and O. It plays tic tac toe via relay logic. About 27 miles of wiring inside.

Tube❄️Time

here are two special tools i used to work on the machine.

the one with the black handle is a contact burnisher. it removes oxides and corrosion from switch contacts without damaging the plating layer (unlike sandpaper).

the other tool is a switch adjuster. you slide it over the metal contact tongue and twist it to adjust the alignment.

Zack Stern

@tubetime oh wow I haven’t heard of a contact burnished (vs high-grit sandpaper). I looked up a little info on them and sounds like it’s the same idea as sandpaper though? You can still scrape through plating past the oxidation?

What am I missing, is the burnished just a lot more gentle than even 2000 or 4000-grit sandpaper? So maybe you could damage plating but unlikely?

Or a totally different sense of all this?

Tube❄️Time

@zackstern yes sandpaper tends to remove too much, too quickly. i guess you could use a fine grit, but a burnisher is easier to manipulate between the contacts.

Tom

@tubetime @zackstern

I was just taught to use a strip of paper. Works really well.

Zack Stern

@tubetime okay thanks. I’ll pick out one of these to try.

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