Repairing a Stern Meteor Pinball Machine

Introduction

I got this game along with Silverball Mania and Tri Zone in a package deal. I did not test any of the three machines when I picked them up, and basically starting this repair as a game in an unknown state. Game looked okay initially. I noticed burnt connectors on the rectifier board, and all fuses tested fine. Decided to go ahead and power on the game and see what happens.

Troubleshooting (Game not booting)

The game would almost boot completing the 6th flash and the displays would show zeros before going out. It seemed the solenoids were about to engage and then the machine would crash. I did not hear any sounds while the game was booting.

Went to the rectifier board and checked the test point at #5. It was 48 Vdc, which is good. Then moved up the train to test point #3 on the MPU,and it was 23V, which is also good.

The nice people on Facebook then pointed me in the direction of looking at R17 (150k ohm), R16 (2.2k), R18 (1.5M), R113 (2.2k), and Diode CR49. All were correct or within spec. The next check was U10 and U14. U14 tested good out of circuit. I had a spare board and pulled U10 from it and replaced it. Now I only got 2 flickers on the test LED. Switched back the original U10 and game now booted! The socket was replaced on the board, and will need to investigate it more. With the game booting, I noticed there was a couple more problems with the game. There was no sound, the right flippers were not working, and half of the GI lights were out on the backbox.

Troubleshooting (No Sound)

There wasn’t too much to this problem. I checked the speaker first, which measured 8 ohms, which is perfect. I then moved to the ribbon cables and noticed the pins were on pins 3-34 and not 1-32. Moved the ribbon cable over 2 spots and the sound now returned.

Troubleshooting (No right flippers)

Started with the basics on the flippers and checked for voltages. 48 volts were present on both flipper coils. Cleaned and adjusted the EOS switch along with the cabinet switch, and flippers were still dead. Grounded the flipper to see if it would fire, and blew the fuse on the rectifier board. Replaced with a circuit breaker for now. Looked at the wiring schematics and connectors and found what was wrong. Somehow the orange connectors should be at pin 8 and was moved to pin 5 for some reason. Moved the orange wire back to the correct position and flippers were now working.

Troubleshooting (Missing GI Lights)

I noticed that half of the GI lights were missing on the back box. I went ahead and added new header pins on the rectifier board. Played one game, and the CPU control lights went out. Checked the fuse on the rectifier board, and it had blown. Spent quite a bit of time working on the rectifier board. I re-soldered the bridge rectifiers as they had bad solder joints, replaced a fuse clip, and re-pinned a couple wires (pin 8 and 13) on J3. Retested the rectifier board and was getting correct voltages on all the test points, but still no change with the game booting.

MPU Not Booting/Sound Problems

Game would occasionally lock up and the sounds weren’t quite right. I wiggled the sound cable on the SB-300 and the problem would go away. I had some parts on hand and made new ribbon cables. The old ones looked like they had seen better days.

Since I was messing around the with sound board, I went ahead and did a cap kit on it.

Displays Flicker

The third player display was flicker/strobbing and this was caused by bad solder joints on the display.

I removed the display can desoldered the old solder and added new to the header pins. This fixed the problem.

Conclusion

Game now boots and plays with no problems. I have to finish adjusting a couple more switches, but am going to call this game done. I played a few games on it, and really enjoy this game. There is so much going on with this early solid state game. I love how the spinner values increase as the meteor drop targets are hit. It’s such a satisfying feeling ripping the spinner when it’s at the maximum score.