(Topic ID: 252204)

Galaxy Stern zero AC voltage on TP4 (first pinball machine)-Update: working!

By 1stpingalaxy

4 years ago


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  • Galaxy Stern Electronics, 1980

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#8 4 years ago

The problem could be in that GI blinking relay. Looks like the blue wire from the transformer goes to that relay then to the rectifier board. I don't know if the relay is normally on lamps or normally off lamps, but if the relay is not working properly it could be permanently interrupting the 7vac getting to the rectifier board / gi lamps. Without looking at the schematics 43vdc and a continuous solenoid driver circuit likely clicks the relay off and on.

Make sure mouser did not nibble on the blue wire going to the rectifier board too.

#10 4 years ago
Quoted from 1stpingalaxy:

Thanks. I'll check that too. I hear the relay clicking when the machine is doing its 'dim the lights' thing but of course theres no effect since there is no power to the GI bus. I'm not sure if that means its good or bad. If I had to replace it, do you happen to know what relay I would use? I saw this one mentioned a few places,but i'm not sure its correct. Does the DC in this relay mean the solenoid driver sends its 40V DC signal to the relay to interrupt the 7VAC circuit? https://www.greatplainselectronics.com/proddetail.asp?prod=LB2-48DS&cat=143

There is a solenoid coil inside the relay box that moves relay switch blades around. Voltage is applied to the coil inside the relay box and then a transistor on the driver board provides the path to ground to make the coil pull in and move the switch blades in the relay box. I don't know 100% for sure but I imagine this relay is going to be a using a 48v rated coil to be powered by the 43v in the game. Its probably the exact same relay that is used on the driver board for the flipper relay. If so the one you linked is probably right but double check.

#12 4 years ago
Quoted from 1stpingalaxy:

Found it! Thank you guys! I traced the leads from the transformer into the relay, bridged past it, and now I've got GI! I don't think this poses any risk since the current is just going to the rectifier board where it passes through the F5 20A Fuse. It was stupid of me to consider the relay 'good' just cuz I could hear it clicking when called upon, as clearly it was cutting off the AC current entirely.
Unless there are any other suggestions, I'm going to order the relay I listed above to replace it.[quoted image][quoted image]

Nice job finding it.

Relays contacts might be welded together, broken or burned. Maybe you can peak inside the case and see whats going on but probably not worth trying to repair the one you got. A new relay will get you going. Consider replacing the relay socket too or just soldering wires right to the relay terminal.

The gator clips I wouldn't use for an extended period as I don't think they can pass 10-20 amp. Could snip loose the two blue wires and wire nut them together until you get the replacement in.

#16 4 years ago
Quoted from 1stpingalaxy:

Thanks. I'm going to go through the connectors tonight. I went ahead and cut the AC voltage I fixed earlier to try and 'get back to where I started' but the dimming issue is still there, and the machine is rebooting on its own sometimes (with an occasional solenoid firing randomly).
I did remove the corroded battery earlier, it was actually the first thing I did before I moved onto anything else. There wasn't any real visible damage thankfully.
I'm not really sure where to start here but I'll probably start by pulling the J1-J3 connectors and testing voltages with various areas isolated first. Then perhaps I can narrow down whats causing the dimming/rebooting.
I was only replacing feature bulbs last night, but perhaps I introduced a short somewhere in the process. I was extra careful, but anything is possible. The fact that the bulb wire has to be unscrewed from the back of the playfield to change them certainly increases the odds of something getting crossed along the way.[quoted image]

MPU looks surprisingly clean. Seems like 90% of originals you come across have battery damage. You can gently flex on the MPU board and it's chips to see if a flaky connection is causing the reset. The 12v regulator has an isolated ground return between the rectifier board and the solenoid driver board. Its common to see that connections toasted at either/both ends and can cause resets if the voltage regulator input drops below the breakdown point. Its an orange wire. Check out the ground modifications to the driver board. Its basically combine all the grounds together at the driver board. They should be pictured with more info on pinwiki and other guides.

Flippers are going to cause some dimming of the lamps. Its unavoidable to some extent but having the rectifier board connections in good shape will help.

If the lamps stay dim while a flipper is held the end of stroke switch on the flipper mech needs adjust to open up at the full stroke of the flipper.

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