(Topic ID: 344352)

Eight Ball Champ Insert Light Issue

By Nchezey_5916

6 months ago


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  • 15 posts
  • 3 Pinsiders participating
  • Latest reply 5 months ago by Quench
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#1 6 months ago

Onto the final stages of bringing a junked Eight Ball Champ back to life. Many of the insert lights were not working, so I ordered up a plethora of replacements. I installed my new backglass/translite, as well as a freshly recapped sound board, and then moved on to what I thought the simplest of my issues was…. replacing a few bulbs.

Replaced insert bulb number one and nothing. Replaced a second and nothing. Decided before I continue replacing a bunch of bulbs that clearly aren’t what’s bad, I’d better pull out my multimeter. I first checked one of the working sockets (on lamp test mode) and my voltage pulses up to the appropriate voltage as the bulb comes on. Move over to one the sockets that wasn’t working and only get 2.3-3 volts. Same thing with the other socket.

What are my potential causes here? I initially thought maybe a corroded or bad connection at the plug/pins on the board, but after unplugging and reseating several times, it didn’t make a difference. Was going to move on to reflowing the solder on all of the associated pins on the board. Anything else I should try first or also do while I’m at it?

Side note- it’s like 30-40 inserts that aren’t lighting on the playfield. Some are next to each other on the same ground and others are just isolated between two that are working.

#2 6 months ago
Quoted from Nchezey_5916:

ome are next to each other on the same ground and others are just isolated between two that are working.

The lamps in these game don't share ground, they actually share supply voltage and the control board switches ground through the individual wires at the lamps.

There are two phases of supply voltages each powering up to 45 lamps. It sounds like one of those phases is out.
Did you check the two fuses on the power module for the feature insert lamp power phases? Fuse FU4 is for phase ØA and fuse FU5 is for phase ØB (both are 8 amp fast blow fuses).

You can also check if the phase voltage is present at those lamps by measuring it. Set your meter to AC voltage (not DC). Put either meter probe on a reliable ground point in the cabinet, and the other meter probe on the bare wire running to the screw base of a non-working lamp socket. You should probably measure around 5-6VAC.

#3 6 months ago

Put either meter probe on a reliable ground point in the cabinet, and the other meter probe on the bare wire running to the screw base of a non-working lamp socket. You should probably measure around 5-6VAC.

I did this and am getting 10VAC. The weird part is, there will be a bare wire going across 3 bulb sockets (with 10v going to it) and only 2 out of the 3 work. I also tested DC voltage to the sockets again and am getting proper voltage to both the working and non-working lamps. I really don’t understand how the lights wouldn’t be working.

I also replaced several more bulbs and verified that none of them changed anything. I also tested the diodes and these seem to be fine.

Is it possible that the sockets could be bad?

#4 6 months ago
Quoted from Quench:

Put either meter probe on a reliable ground point in the cabinet, and the other meter probe on the bare wire running to the screw base of a non-working lamp socket. You should probably measure around 5-6VAC.

I did this and am getting 10VAC. The weird part is, there will be a bare wire going across 3 bulb sockets (with 10v going to it) and only 2 out of the 3 work. I also tested DC voltage to the sockets again and am getting proper voltage to both the working and non-working lamps. I really don’t understand how the lights wouldn’t be working.
I also replaced several more bulbs and verified that none of them changed anything. I also tested the diodes and these seem to be fine.
Is it possible that the sockets could be bad?

#5 6 months ago

Reading a couple of other threads, could the transistors that control those bulbs be bad? Would shorting the socket kill the transistor that controls it? I had a socket that I accidentally shorted against another one while messing around today. The bulb went out and it’s acting exactly the same as the other “dead” ones now.

#6 6 months ago

Yes. The drive SCR may have failed. The upstream decoder may have failed also.

Chris Hibler - CARGPB #31
Http://chrishiblerpinball.com/contact
Thank you for checking out the PinWiki - http://www.PinWiki.com/

#7 6 months ago
Quoted from ChrisHibler:

Yes. The drive SCR may have failed. The upstream decoder may have failed also.

Chris Hibler - CARGPB #31
Http://chrishiblerpinball.com/contact
Thank you for checking out the PinWiki - http://www.PinWiki.com/

Is there an easy way to tell which SCR goes to which bulb? Is there a diagram or schematic of this in the manual?

#8 6 months ago
Quoted from Nchezey_5916:

Is there an easy way to tell which SCR goes to which bulb? Is there a diagram or schematic of this in the manual?

There's a page in the schematics that lists which SCRs drive which lamps.

The SCRs can each control two lamps. The specific lamp of the two is dependent on the half rectified DC phase it lives on and software triggering it on that active phase. Manually jumpering in any of the following tests will illuminate both lamps connected to the SCR/colored wire. For example if you look at the below SCR list, the Bonus 15k and Bonus 240k are both driven by the same SCR (Q67) and colored (yellow) wire but are on opposite DC phases.

If you jumper a wire from ground to the colored control wire on the lamp socket, the lamp (and it's respective one on the opposite phase) should illuminate. If it doesn't the problem is local to the lamp socket.
The SCRs on the MPU control board basically switch ground to the colored control wire at the lamp sockets.
The 'anode' leg of the SCRs connects directly to the colored control wire at the lamp sockets. You can jumper ground to the anode leg of the respective SCR to check connectivity from the control board to the lamp socket. The lamp should light when you do this. If it doesn't you have some connection issue.

Finally, test point TP7 on the MPU control board allows you to manually trigger/test the SCRs so it switches the lamp on. Jumper a wire from test point TP7 to the 'gate' leg of the SCR.

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#9 6 months ago

Quench
Excellent.
I’m going to add this info to the PinWiki if that is OK with you.

Chris Hibler - CARGPB #31
Http://chrishiblerpinball.com/contact
Thank you for checking out the PinWiki - http://www.PinWiki.com/

#10 6 months ago
Quoted from ChrisHibler:

I’m going to add this info to the PinWiki if that is OK with you.

@chrishibler, no problem, I added more for clarification in that post. Hope I didn't achieve the opposite by making it confusing..

#11 6 months ago
Quoted from Quench:

There's a page in the schematics that lists which SCRs drive which lamps.
The SCRs can each control two lamps. The specific lamp of the two is dependent on the half rectified DC phase it lives on and software triggering it on that active phase. Manually jumpering in any of the following tests will illuminate both lamps connected to the SCR/colored wire. For example if you look at the above SCR list, the Bonus 15k and Bonus 240k are both driven by the same SCR (Q67) and colored (yellow) wire but are on opposite DC phases.
If you jumper a wire from ground to the colored control wire on the lamp socket, the lamp (and it's respective one on the opposite phase) should illuminate. If it doesn't the problem is local to the lamp socket.
The SCRs on the MPU control board basically switch ground to the colored control wire at the lamp sockets.
The 'anode' leg of the SCRs connects directly to the colored control wire at the lamp sockets. You can jumper ground to the anode leg of the respective SCR to check connectivity from the control board to the lamp socket. The lamp should light when you do this. If it doesn't you have some connection issue.
Finally, test point TP7 on the MPU control board allows you to manually trigger/test the SCRs so it switches the lamp on. Jumper a wire from test point TP7 to the 'gate' leg of the SCR.
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Thank you for the wealth of information! I was not understanding how this Bally light setup worked and now have a fairly decent understanding.

I was finally able to get some time to work on the game again tonight and out of the first 5 bulbs checked, all of them lit during lamp test when I jumped them with a ground! I’m currently going through all of them to verify and will report back on what the final verdict is.

#12 6 months ago

I finished going through the game and found 25 potentially bad SCRs. I did find a handful of bulbs (maybe 6) that were just burned out and a couple of diodes that were to blame.

Pulled the board out and immediately found the culprit. Someone must have made a hack attempt at replacing some SCRs already as there were several broken, missing, or poor quality solders on the SCR portion of the board. I replaced two of the SCRs, replaced the board and BAM!!! associated lamps working perfectly.

The bad news is I’m out of desoldering wick, so couldn’t get any further than the two SCRs for tonight. Hoping I can find some local tomorrow and won’t have to order online. I’ll provide an update once I’m able to replace the rest of the SCRs, but looking like it could potentially be the extend of my issues.

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#13 5 months ago

Finally got a chance to test out the board after replacing the SCRs this week. ALL LAMPS ARE LIGHTING NOW!…… however, I now have a new issue; there are 7 lights that stay lit all the time (not including the two rollovers which I heard are supposed to stay on). 6 are on shared SCRs and 1 solo (so 4 SCRs associated). From everything that Ive read, the only thing that would cause a lamp to stick on is a bad/stuck SCR. My current theory is that I got a few bad SCRs??? (I did buy a bag of ‘old stock’ one from eBay and replaced roughly 20) Before I replace them though, is there anything else that would cause the lamps to stick on?

#14 5 months ago

All good to go now! Did a little more homework and found a thread where it discussed that when two bulbs share an SCR and are stuck on, specifically with one being brighter than the other that it is an issue with the diode on the lamp socket. This was the case for me on a couple so I replaced 2 diodes to get 4 of the 7 remaining lights working correctly. I then discovered that the other ones were on completely different SCRs than I had replaced. I must have either missed them during my initial diagnosis or they got shorted during everything else I was doing. Regardless, I got the final two SCRs replaced and now all lights are working as they should.

All-in-all it looks like about 4 lamps had bad or broke loose diodes, 5-7 were just burned bulbs, and roughly 23 SCRs that were bad (or just previously installed poorly).

#15 5 months ago

Boy that's a lot of bad SCRs which is unusual, though the previous suspect work may have been someone exacerbating the problems.

I worked on an Eight Ball Champ for someone six months ago, not expecting much from the layout but was really surprised how much I liked the game. Glad you're up and running and hope you enjoy it too.

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