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19 comments
Tube❄️Time

the subtract pawl on the player unit was getting stuck. cleaned it and it works now.

Tube❄️Time

one interesting issue is that there are a lot of corroded connections and switch contacts. this machine has less than 7k hours on it and it has sat in storage for 40 years.

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.

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.

JeffG

@tubetime 7000 hours or quarters? I just clean the contacts with alcohol and a biz card. If theyre adjusted properly, the switches should "rub" and self clean. I think theyre usually 70v.

Owen Mehegan

@tubetime how do you know how many hours it has? Is there a counter, like on an airplane engine?

Tube❄️Time

@literatesavant yes it has an hour meter for accumulating play time.

.vad//hakara🧭

@tubetime That has to be the cleanest pinball wiring I have ever seen

Phil Betts

@tubetime I thought this was an elaborate Micromachines playset when it first popped up. I guess in many ways it is.

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