Quoted from jsa:Any thoughts on how to clean scorch marks off the metal backbox sheeting?
Orbital buffer
(Topic ID: 208174)
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Quoted from jsa:Just polishing compound?
Just go up through the ranks.
Heavy to fine
Might have to sand them out first with 220 or 340
3 weeks later
Might need a washer on the blackbox hinge to keep if from scraping.
Some of my games have 3 due to sagging/wear of the hinge bracket.
I like the laminated blackbox labels! I was thinking maybe mat or non glossy finish for those might be easier to read based on the room lighting when I re-do mine.
1 week later
Quoted from jsa:The back looks pretty good now to me, now that it's been sanded smooth. Painting more of the back would essentially be painting spots that are covered by hardware at this point, IMHO...and I hate the idea of getting paint on any of those inserts.
Do it Kruzman style and apply a thin single coat of shellac or poly with a foam brush?
It doesn't have to be pretty it's for protection.
Stick a soft sponge in each hole as you go, it's not too bad at all.
The theory is that the coating will ward off black fingerprints in the future and it's somewhat washable.
And it's a nice touch.
Quoted from jsa:Side question: The playfield wood rails were long stapled to the playfield. There were screw holes, but no screws. Have most of you re-attached the rails with screws? That’s our plan, but the whole thing strikes me as curious.
Those staples were super long and not fun to remove.
Re-attach with the screws only.
The staples are unneccessary.
Modern games are with screws only now.
3 weeks later
Quoted from jsa:For the record, this is the wiring that worked and cleared the stuck switch issues:
[quoted image]
I have no idea if the diode is necessary (it wasn’t in the original wiring), and the switches are now N.O., but it cleared everything up. On to debugging mechanical (gate barely moves and have to adjust the flippers).
I dont know if this applies, but there are tons of errors on schematics. Most have been documented. This might be a new one.
I tighten the pawl until it starts to grab the flipper but it still can be moved firmly
Now it stays place enough after adjustment to tighten fully.
Make sure the flipper plungers are perfectly Inline with the coils and sleeves.
The gap above between bat and playfield should be present and not allow the bat to drag on the surface.
Make sure no debris in the sleeves or on the stops.
1 week later
Quoted from jsa:Well, I swapped Q14 and Q31 (unused on Future Spa). I unplugged the playfield/cabinet/lamp panel connectors from the LDB so nothing there could fry the SCR. I then hooked up a socket with an incandescent to Pin 18 on the LDB (center target S, Q14) and the other lead to the TP1 on the rectifier. No change, flickers when on. I also re-crimped/terminated the ZC wire between the rectifier and MPU. No change.
I honestly can't think of anything else except for something bizarre on the rectifier board. I think my next move here will be to swap the rectifier/transformer with a known working rectifier/transformer and see if there is a change. I suppose I could put my old rectifier back, but it was such a frankenstein mess that I'd prefer to let it be vs. desolder/resolder the whole thing, plus figure out how to manage the hack jobs. Also, I'm confident in barakandl's work.
Have you tried adding a 370 or 470 ohm resistor in series to the lamp to increase the load? This should force the SCR to zero out unless you have ground problems.
Quoted from jsa:Yes, I have. No change. I've also tried that with an Alltek as the LDB and that also has a 470 ohm resistor built in, and connected to the 6.3vdc control lamp rail as well.
What we have is, for whatever reason, the control lamp on just address 0 on the four decoders doesn't hit the necessary on voltage on every cycle. You see the spike, so it's trying, but it doesn't do it. It's like something is sucking the voltage away. Most of the other SCRs work fine, I have mixed experiences on AD1. We're talking about maybe 15 lamps of the whole thing behaving this way.
Note also, you can unplug ALL the lamps from the LDB, and check the waveforms on the gate legs of the SCRs, and you'll see it there. It's nothing on the playfield.
If that is the case then I would replace the SCR's with ones from a different vendor/manufacturer. They might be out of spec or another component on the LDB is making them unhappy.
Quoted from jsa:I did a swap of SCRs already, and I also swapped the entire LDB (between original Bally and Alltek), same results.
DC ripple or noise in the ground system? If its in the board then its a supply line problem either power or ground.
Quoted from pinballinreno:If its in the board then its a supply line problem either power or ground.
You shoud be able to see it on the o-scope. Possibly from the power supply.
Quoted from pinballinreno:You shoud be able to see it on the o-scope. Possibly from the power supply.
Could definitely be a rectifier problem. DC ripple causes this sort of thing to happen.
If you think about it, the SCR is being knocked loose and dropping the latch.
Quoted from jsa:I love it. What should I connect to to measure the wave form and find the ripple?
I dont have the game to look at but I would test the input power and ground, then compare it to the output power and ground.
Ground should always be dead. Start at the source and work down to the SCR.
Voltage should be very flat DC after the rectifier, no pulsations. If not then the rectifier isnt doing its job.
Quoted from jsa:Ok, so what we're talking about is measuring AC power as it comes into the line filter, measure it after the line filter, as it goes into the rectifier, then measure the output DC voltage waveform coming out of the rectifier heading towards the MPU. Could I do that with the test points?
Yes as well as some careful probing onboard. Follow the power paths on the schematic.
Quoted from Quench:The job of a rectifier is to convert AC to DC. It does not remove ripple - that's the job of a filter capacitor/regulator.
The lamp DC supply was already measured here with your scope (second image):
https://pinside.com/pinball/forum/topic/bally-as-2518-club/page/26#post-4620933
As you can see it is rectified but unregulated DC (full of ripple). The whole design of this lamp circuit relies on the ripple dropping to zero volts in order for the SCRs to switch off. If the lamp voltage was flat regulated DC the lamps would never switch off.
So, a filter problem?
I totally admit Im rusty on this stuff. But it seems that the power isnt stable enough to stay latched.
Something in the ground or power supply that isnt being addressed.
Quoted from pinballinreno:So, a filter problem?
I totally admit Im rusty on this stuff. But it seems that the power isnt stable enough to stay latched.
Something in the ground or power supply that isnt being addressed.
Low or anemic current flow to the SCR?
Quoted from pinballinreno:Low or anemic current flow to the SCR?
My premise is that its power or ground related since its not the playfield or LDB boards.
Quoted from jsa:I've heard this from friends who repair pins in SF... That it "smells" of power or ground related issues. While no one has a specific suggestion, the ground could be suspect. When we restored the cabinet, we ran new ground braid, and followed the original path, with one exception: We eliminated all the unnecessary loops that the original game had put in the main cabinet. The backbox, though, is 100% identical.
If I were to run a jumper from the rectifier board to the lamp driver board, what exactly do you mean? You're talking about disconnecting the power and ground from the board connectors, and running it directly somehow to the rectifier?
Since you changed out the rectifier board, and the original rectifier board worked, the problem is with the rectifier board.
I guess you could put the old one back in, it's a a lot of work but would give you a base line test.
Im not clear on the differences between the 2 types of boards. taking some measurements might be enlightening.
Quoted from jsa:No, this didn't happen... I didn't change out the rectifier board yet. What I mean is, we haven't done a swap...But yes, the original one worked before the restoration.
Sadly there is only one way to find out if it still works.
Quoted from jsa:Ok, first I'm going to try bypassing the ground path and doing a jumper from the LDB to the rectifier ground, just for giggles. If that doesn't work, the next step is a rectifier swap, and I may wait to do this until I have a confirmed working transformer/rectifier pair I can temporarily borrow just to see if it changes things.
My money is on the new rectifier board having subtle differences from the old one.
Quoted from jsa:Well already there are some differences for sure. The original is a AS-2518-49. The repro is closer to a AS-2518-18, but they are supposed to be compatible. The one main difference is the feature lamp fuse on the -18 is a 10amp fuse, and on the -49 is a 20amp fuse. So I'm running the feature lamp bus on 10amps, but I can't see the difference that would make other than blowing the fuse if I push it too far. If you look at connection point E9, you can see that the original board had a place for two wires to terminate. For the repro, I twist those wires together and go into a single connection point.
Just for reference, here is a photo of my original board:
[quoted image]
[quoted image]
Here is the new board:
[quoted image]
[quoted image]
The new board sure is pretty and well organized!
But the old board is certainly good enough to be cleaned up and put into service.
It would take a couple hours to completely rebuild it, but it would work well.
definitely a difference in current flow from 20a to 10a.
Definitely a minor current difference on connection E9, but still a difference.
Maybe send the old board out for rebuilding if you dont feel confident. Its super easy with a proper station and tools.
But I would do nothing until I test it in your existing game as it is. I wouldnt add any more random issues while troubleshooting.
Quoted from Quench:What's the likelihood all three of those wires have poor connections after you've re-terminated them all?
Try running a jumper wire from the lower leg of either white ceramic resistor on the rectifier board directly to the ground test point on the lamp driver board and see what happens. Be careful you don't jumper to the wrong spot and blow stuff up.
The curious thing about your SCR waveforms is there is always two missed latches in a row..
There are some current flow differences from the old rectifier board compared to the new one.
Whether the current is actually used or not, it may just be an issue of lower potentials keeping the SCR from latching firmly.
Something like a low wattage supply vs a higher wattage supply. You get more lively snappy performance at the same voltages.
Quoted from supermoot:Just wanted to confirm and say, hey, I'm running an old -18 in a future spa with no weirdness.
That's good to know.
Did you convert to LED's?
Quoted from jsa:One other clue that we uncovered in the other thread...
Most of the lamps that are address 1 or above on the decoder clear up after the game heats up for 5-10 minutes and stop flickering.
It's only the address 0 lamps (rollover F and SPA target) that keep flickering after warm up.
This means something heats up and changes the behavior. What changes when heated?
-Solder joints (but that would have to be the rectifier, since we swapped out the other boards)
-Resistors on the rectifier?
-Resistance increases?
-Something expands and moves a short circuit out of short?
-Metal pin or female connector trifurcon expands making better contact?
Maybe a current flow issue.
Not voltage.
More resistance after warming up.
Less current would lower the performance of the SCR, it would become slightly weaker and not latch properly.
Definitely power related.
Just an obvervation.
You have done everything except put the old rectifier board back in?
It might be informative to see the differences between the new and old while in service on your game.
It's a pain but really only a 1 hour job or less.
Quoted from jsa:I just worry I'll go through this whole process and achieve no different result. It's worth it though, because then I'll have a backup rectifier.
Try not to be the glass half empty guy 
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