(Topic ID: 324936)

Smoking Playmeter in 1974 Williams Skylab

By Dan_Halen

1 year ago



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#1 1 year ago

I was out with a friend last weekend picking up some machines and one of the gentleman we were picking up a machine from said he had a Skylab that wasn't working and asked if I knew how to fix machines. I've been dabbling in SS machines for years now, and recently picked up a Gottlieb Pro-Football so I could start learning EMs. I'd like to start dipping my toes into professional repairs, and this seems like a great opportunity to get a first client.

I started taking a look in the machine and found a blown fuse on the fuse panel directly to the right (I believe it was a 15A, but I may be mistaken, and it may have been the wrong fuse). We swapped that out and got the machine to come on, but immediately the Total Play Meter (the box that counts how many games have been played) started buzzing. While mildly concerning, we kept looking around in the machine. After a moment I noticed the meter was hot, and smoking a little. At this point we turned it off and unplugged the machine, but now I'm not sure where to look.

He asked me to come back when I have more input, so I just want to see what I should be looking for and what to do. I also have a Williams Triple Action machine here I can look at in the mean time, they're fairly similar in build, so at least I have some reference rather than none at all. I stupidly didn't think to take any pictures, but I suppose I could ask for some if needed.

Any input would help and I thank you all in advance for your time.

#2 1 year ago

I would check the following switches.
I suspect the coin relay.
If the coin relay is also stuck on. check the coin chutes for stuck coins or closed switch on one of the chutes.
schematics and manual can be found here: https://www.ipdb.org/machine.cgi?id=2202

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#3 1 year ago
Quoted from ArgosySK:

I would check the following switches.
I suspect the coin relay.
If the coin relay is also stuck on. check the coin chutes for stuck coins or closed switch on one of the chutes.
schematics and manual can be found here: https://www.ipdb.org/machine.cgi?id=2202
[quoted image]

Perfect! Thank you @argosysk. I did download the schematics, but am fairly new to reading them, so this is a huge help. I'll see when I can take a look at it and if anything comes up, I'll report back.

#4 1 year ago

Out of curiosity, did the credit unit decrement?

I once had a Williams Doodle Bug with the same circuit. In that one, the Total playmeter wires were shorted which resulted in high current going through the center leg of the parallel circuit and virtually no current to the two outside legs. Thus the credit unit would never decrement and also the fuse would soon blow.

Wondering if the coil inside the Skylab playmeter has a very low resistance which is resulting in high current through it due to a maladjusted coin relay switch?

#5 1 year ago
Quoted from Runbikeskilee:

Out of curiosity, did the credit unit decrement?
I once had a Williams Doodle Bug with the same circuit. In that one, the Total playmeter wires were shorted which resulted in high current going through the center leg of the parallel circuit and virtually no current to the two outside legs. Thus the credit unit would never decrement and also the fuse would soon blow.
Wondering if the coil inside the Skylab playmeter has a very low resistance which is resulting in high current through it due to a maladjusted coin relay switch?

I am going to see the machine tomorrow, I'll try to make a note of this and get back to you

#6 1 year ago

Not sure how accessible the total playmeter leads are, but you might try and measure the resistance if you have a multimeter. If it measures way less than 2 ohms or so, the coil may have been compromised at some previous time and is in the process of internally shorting out due to insulation having been burned off the wire. Also sounds like one or more of the number dial mechanisms may have broken or jammed (since it is making a buzzing sound).

Lee

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