(Topic ID: 344656)

System 80 Controlled Lamps Issue

By xcguy

9 months ago



Topic Stats

  • 8 posts
  • 3 Pinsiders participating
  • Latest reply 9 months ago by xcguy
  • Topic is favorited by 1 Pinsider

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#1 9 months ago

Continuing work on a 1980 Gottlieb Amazing Spiderman (System 80), with what appears to be all original boards. The machine largely works, but I'm currently stumped on an issue with some of the controlled lamps. The bonus lamps above the top three kick-outs (labeled L12, L13, L14) and the bonus lamps in front of 5-drop targets (lamps L15-L19) never turn on. The rest of the controlled lamps work, so it's not the F3 fuse. I've checked the bulbs and verified it's just those two groups from the diagnostic lamp test. I've also checked the connections between the MPU and driver (A1J4-A3J1) and the driver to playfield connector (A3J3), both connections tested fine. And I checked the fuses near the back of the playfield.

Seems strange the failure is just those two banks. On the driver board, those banks are spread across to two SN74175N (Z4 and Z5 in schematics), and each light has their own MPS-U45 (labeled Q13-Q20). I've attached photos of the driver board with those components. Any ideas on what could cause just those two bonus groups to stop lighting? Appreciate any tips.

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#2 9 months ago

1980 there might still be some relays stacked switches being used needing adjusting.
Check under the playfield.

#3 9 months ago
Quoted from Wariodolby:

1980 there might still be some relays stacked switches being used needing adjusting.
Check under the playfield.

I did examine those, but wasn't certain how to test? When powered off are they all suppose to be open? I've attached a photo of the two relays (power off).

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#4 9 months ago

They adjusted correctly but could still be dirty.
Be gentle and use the credit card method for cleaning them.
But before you do that,just try engaging them with the game on see what they activate.
I see the one is tilt what’s the other one for?

#5 9 months ago

The one is the tilt relay, the other is the game over relay. When powered on, the tilt relay will engage just briefly (like part of the boot up test). The game over relay engages until powered off (or end of game, I believe). I did clean the contacts, no change. I think if there was an issue with those relays, I'd have more wide spread issue with all the controlled lamps -- not isolated to just two specific bonus groups.

#6 9 months ago
Quoted from xcguy:

The bonus lamps above the top three kick-outs (labeled L12, L13, L14) and the bonus lamps in front of 5-drop targets (lamps L15-L19) never turn on.

Since lamps L12 thru L19 share the same ground connection at the driver board, that would be my first guess: Confirm those transistors are getting effective ground through driver board connector J3 pin Z.

AmazingSpiderman_Lamps_L12-L19.pngAmazingSpiderman_Lamps_L12-L19.png
AmazingSpiderman_Lamps_L12-L19_Gnd.pngAmazingSpiderman_Lamps_L12-L19_Gnd.png

#7 9 months ago
Quoted from Quench:

Since lamps L12 thru L19 share the same ground connection at the driver board, that would be my first guess: Confirm those transistors are getting effective ground through driver board connector J3 pin Z.

Oh boy, this was a great guess - would fit all the symptoms! But... I tested A3J3-Z crimp pin to transistors Q13-Q20, that's good. Then checked A3J3-Z back down to ground board at the bottom of the machine - that's good. So it looks like that's not the issue?

Only thing that is a little confusing is the A7J5 connector. It's a 15 pin connector, and the schematics say A3J3-Z connects to A7J5-3, however, I found it connects to A7J5-5 instead. Probably not an issue, as A7J5 pins 2, 3, 4 and 5 are all grounds. Only other strange thing with A7J5 connector is pins 13 and 14: on the female side they are 25VAC (from the transformer) but the male end has no pins, i.e. it doesn't connect to anything. Can't see how that would relate to the controlled lamps issue I'm fighting though.

Any other ideas?

#8 9 months ago

Well, it happened again... the problem "fixed itself"! I spent the day going back to the basics on the controlled lamps, testing the voltage at the lamp mounts when connected to ground (5.8 VDC), and then testing the voltage using the lamp tab when the circuit was suppose to be activated. I could see some voltage getting cycled into the problem groups on the lamp tab when the game was in attract mode, but it appeared to be quite low (around 1.5 VDC). I decided to pull all the bulbs from the two groups and get some more voltage readings. Still low, so I decided to reinstall some bulbs again and get some final readings to report. During that process I suddenly noticed the bulbs were coming on! I reinstalled all the bulbs, and yup, the problem has gone away -- all the controlled lamps are working now. Crazy. I can only guess that there was some grounding issue that must've been "fixed" when I was removing and reinstalling bulbs. I inspected most of that wiring, didn't see anything obvious.

I'll see how long it remains stable, but I played a number of games tonight, everything was working (well, except the 'match' feature). Thanks everyone for the suggestions and tips!

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