Arcade Collecting > Restorations & repair

Skee-Ball Model S Restoration: F2 Fuse Keeps Blowing?

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l1nt:
Hi All, just getting this machine together and my F2 .5amp 250v slo-blo is blowing frequently. I can get the ball release solenoid to work a few times before it acts caught up or just doesn't attempt to fire. I have replaced the solenoid even though the ohms read fine on the old one. I just took apart all the linkage to check for excessively worn parts but all seems well. I cleaned everything up and reassembled. Everything moves by hand very smoothly. Can anyone recommend what to test next?

lilshawn:
you say it's acting stuck? and you are looking into it being stuck mechanically, despite the fuse blowing.

a mechanically stuck solenoid will not blow a fuse... it would simply just not move properly.

it sounds like it's being stuck ON and being stuck OFF by it's control circuit.

if you get yourself a small incandescent bulb... something like a nightlight bulb. wire it on in parallel with your release solenoid and have it outside the cabinet so you can see it.

actuate your solenoid and make sure it's 110v power is being supplied/turned off appropriately. if it's not being turned on and off properly (which i believe it is not doing it properly) you'll have to look at everything i circled in the circuit... if the resistors check out within specifications, change out the triac.

EDIT: alternatively, if you are unable to source a replacement triac, i can direct you on how to modify the circuit to drive a relay or something... while not ideal, it will work.

l1nt:
Thanks lilshawn for the feedback. I was assuming binding on the linkage because when it fails and blows the fuse usually there is a slight attempt at pulling back the plunger and then fuse is blown. I already have new replacements for the TRIAC (SC146D) in-case that was the issue. Not sure I have the equipment or know-how to rig a test light but I will see if I can. I will test the resistors in circuit and go from there.

I really appreciate your second set of eyes.

lilshawn:
no worries. at this point i wouldn't worry about the light... it's just something i suggested to verify the issue.

what i was getting at, and how i processed your issue in your post.... is that nothing electrically changes about the coil, whether the linkage is jammed, or stuck or even not there at all. (in the grand scheme of things) all the solenoid is, is a coil of wire in a circuit.

if there was, say... a chafed section in the coil because of damage or it got overheated and shorted out inside... it can cause the fuse to blow because the expected load of the coil is different to what it's supposed to be.

if, for example... the coil is 100 ohms... at 120v, it passes 1.2 amps... fine for a 2 amp fuse.

but a damaged coil could be something maybe 30 ohms ... this would pass 4 amps. no bueno.

and because you changed the coil out already, and also measured the new coil's resistance against the other, it doesn't seem like there is any issues there. (though i wouldn't discount an issue with the old coil causing the issue with the board triac... high voltage stuff can test good when tested with the low voltage of test equipment like voltmeters... but fail when the full beans get put through it.)

but you said it still does it with the new one as well...

so the fuse still blowing even with a new solenoid is indicating to you that there is an electrical problem further up... citing no shorted to ground cabling issues going back to the board, your issue is likely with the triac since it's in line with the coil...and the coil is known to be good.

capacitors can short out too  which is why i also circled that C15 in the circuit it is also in line with the solenoid to an extent. normally they do not have a "resistance" per se, but they can have leakage and fail, (usually short circuit) causing current to pass through them. i'm not sure why it's there in circuit, probably something to do with biasing the triac or changing some property of it's switching or something like that....  i'm old, but triacs are even really before my time in electronics... and we don't even really use them anymore, so i haven't bothered to look into them much.

l1nt:
will report back once I pull board and test. thanks again for your opinion and passing on some wisdom!

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