(Topic ID: 280260)

Sanity check: Backbox GI string out in Williams System 9 - Sorcerer

By dEviant

3 years ago



Topic Stats

  • 6 posts
  • 2 Pinsiders participating
  • Latest reply 2 years ago by dEviant
  • Topic is favorited by 1 Pinsider

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#1 3 years ago

I'm hoping that the Pinside hive mind can provide me with a sanity check, because I don't always trust my troubleshooting skills and this one is driving me nuts.

Backstory: My otherwise fully working Sorcerer had a single display out, so I wanted to replace it with a PinScore system. That part was straightforward enough, and within a few minutes I got that problem resolved. But then I noticed that one string of GI lights on the backbox was out. This was most certainly not the case as I had just taken some pictures a week or two ago that show that everything works. Here is what I did to try to figure out the problem:

- Measure voltage across any lamp socket on the non-working GI string confirms that there is nothing there
- Switch out a few bulbs to rule out that somehow all of them burned out at the same time. There were a few burned ones but most of them work fine
- Replace power board with brand new XPin one (which was on the todo list so now is a good time as any) The connector to the power board with the 4 GI lines does show some signs of being toasted - so this will get replaced asap
- Measure voltage at connector on power board - OK
- Measure voltage at connector to the GI lights - OK
- Disconnect connector, remove all the bulbs from the non-working GI string, measure connectivity, there appears to be a short. Reconnect connector, measure voltage, still nothing there
- Disconnect connector, remove all the bulbs from the working GI string, measure connectivity, appears to be open. Reconnect connector, measure voltage, OK

My thinking now is that without any bulbs in place there should not be any connectivity between the 2 GI lines. The presence of a short would explain why there's no voltage and nothing lights up in that string. So my next steps should be to:

- visually inspect whether there is anything obvious causing the short, blow some compressed air into the sockets, see if that works
- desolder one side of all the sockets connected to that GI line, so that I can measure connectivity across them, and see which socket is the culprit/shorted and needs to be replaced

Now before I start desoldering... Am I missing anything? Is there something else that I could be checking that could cause the string not working? Anything else I should check for first?

Thanks for reading, and thank you in advance for your help!

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#2 3 years ago

Well, after posting this I realized that if one of the lamp sockets is shorted, that it is most likely that springy-thingy in the middle making contact with the outer shell. I did some poking around with the DMM but have not been able to identify the culprit (there's so many of them - but fortunately they are in a relatively accessible location compared to e.g. GI strings on the playfield). So then when I searched for replacement lamp sockets, the search suggestion 'short lamp socket pinball' came up, with plenty of posts confirming the thought process/approach outlined above. So that makes this post pretty redundant then. I just had not thought of using those search terms (in hindsight: DUH!). I tried to delete this topic but apparently that cant be done without mod interference. Oh well, maybe leaving this post up will be of help to someone else Thanks for reading!

#3 3 years ago

Aaand I'm back to being confused. After poking at the lamp sockets a bit more I got the short resolved. With the power on and without any bulbs installed, the voltage on the problematic GI string is now OK, and with power off and the backbox GI connector disconnected, there is no connectivity across the string. So far so good. But as soon as I place one bulb, when powered on the voltage across the GI string drops to 0. Voltage at the appropriate GI line at power supply is still OK, fuse does not blow (I pulled it/tested it/replaced it even though it seemed ok but as hinted at in the OP title I'm slowly losing my mind over this one ).

With the power off, the backbox GI connector disconnected, and GI bulbs removed from both GI strings, the 'problematic' GI string measures around 26 MOhm, while the OK GI string measures infinite MOhm.

My best guess is still that there is one lamp socket that is causing a problem. But the problem is not as straightforward as it initially appeared to be. I will sleep on this one for a few days, and unless anyone replies to this post with additional insights/suggestions, I'll just order a batch of lamp sockets and start soldering. I will at least desolder/test all lamp sockets. If I can isolate the source of the 26MOhm resistance then I will just replace that one. Worst case I just replace them all

Thanks again for reading. To be continued...

#4 3 years ago

You are insane...

#5 3 years ago

You have to be, in this hobby of ours

7 months later
#6 2 years ago

Following up on this thread with a resolution that can be archived for digital eternity. I recently started desoldering the lamp sockets on the affected string one by one, to try to figure out what was going on. I fully expected that one of the sockets was broken/shorted. As it turns out, the lamp sockets were not the problem, but instead one of the GI wires had broken in two places - one of which being where the +/- is fed to the string. I just would not have guessed this, ever - especially since there was some residual voltage across the two GI wires, and while enough to turn on a LED bulb, it was not enough to turn on an incandescent bulb. There was some finite resistance between the two wires but by now I realize that that was 'clerical error' and not at all what it seems. Anyway, the amount of solder present at those locations suggests that this has happened before and someone tried to 'ghetto fix it' by just adding more solder to bridge the gap. While waiting for the replacement GI wire that I ordered, I reinstated the ghetto fix. One more step towards the much coveted fully correct electromechanical functioning

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