Stars
Stern Electronics, 1978My Stars (Stern, 1978) used to be fully functional but for whatever reason the chimes have stopped working. I found that the chimes box fuse (inside cabinet on left side) was blown and replacing several times resulted in it immediately blowing upon booting up the machine. I don't see anything obvious like loose wires or fried electronics by the chime box coils or in the back box. Not sure where I need to look next to solve the problem. Any ideas would be appreciated.
Quoted from Flippingr8:My Stars (Stern, 1978) used to be fully functional but for whatever reason the chimes have stopped working. I found that the chimes box fuse (inside cabinet on left side) was blown and replacing several times resulted in it immediately blowing upon booting up the machine. I don't see anything obvious like loose wires or fried electronics by the chime box coils or in the back box. Not sure where I need to look next to solve the problem. Any ideas would be appreciated.
Locked on chime coil?
Measure the resistance of each chime solenoid. One may be shorted. If so the associated driver transistor is probably damaged too,
Quoted from barakandl:Measure the resistance of each chime solenoid. One may be shorted. If so the associated driver transistor is probably damaged too,
Can you walk me through how to do that? Without disconnecting any of the wiring in the machine, but with power off, if I use the ohm-meter across each of the 4 coils, it goes from infinity (1) to zero. Isn't that normal?
DMM set on resistance. Measure across the coil lugs with the power off. Resistance will be fairly low and each one should measure about the same. Any coil below 2 ohms or so is bad. I would guess a chime coil would be about 10 ohm.
3 of the coils test in the 40-50 ohm range. 1 tests at 11 ohms. They are labeled Stern N-31 2000; see attached photo. Is the difference between the one coil and the other 3 significant and potentially the cause of the blowing fuses?
I did note that the one coil that tests at 11 ohms had a diode across it with a broken off lead; the other 3 didn't. Could that have ruined it?
detail.jpgYou found your problem. Disconnect the low resistance coil and see if it stops blowing the fuse. If it does not blow the fuse anymore go to the backbox and test the driver board transistor (it is probably bad).
See pinwiki for info on testing solenoid transistors. All solenoid coils should have diodes on the coil lugs.
I see on the flippers.com coil resistance chart that this particular coil should have a resistance of 48.8 ohms. Is 11 ohms bad enough to blow a fuse?
So in the middle of fiddling around w this thing I turned it back on because I thought I had blown the fuse again and I wanted to try the machine and get it ready for a party this weekend. I turned it on and it seemed like everything was working fine, chimes included. I thought somehow I fixed the problem. Well, about 3 minutes later the play field hazed up, and I started smelling smoke. Turned that sucker off. And lifted up the play field to find the bad coil, burnt up. The inner chime plunger was melted. Almost had a fire. Dodged a bullet. Think that last fuse I put in there was a 3 amp slow blow, cuz I was out of 1/4 ampers. Learned a good lesson
image.jpgThe one that burned up was the one that measured 11 ohms resistance earlier, whereas the other three were around 45 ohms.
As Andrew said, you had found your problem.I'll let the others work you about the fuse. 11 ohms is close enough to a short.Also as Andrew said, it's probably the transistor on the driver board. I would just take that chime out of the mix for now by cutting the wires and go with the other 3 until you get this fixed. Hope the smoke didn't mess up yer playfield too much. Probly stinky.
The chime plunger's nylon tip melted. Where can I get a new plunger with tip? These measure 1 3/4" from end to end, and the ones on Marco are 2 1/2" long. I've attached a photo of one of the other 3 from the machine. I believe that I (stupidly) threw out the metal part of the melted one so just replacing the nylon tip won't be an option. Here is a photo of an unmelted one. Thanks!
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Delafield, WI