- pop bumpers sometimes fire when left flipper hit and ball not near them

This has been well documented now, several fixes exist. Check this post here. https://pinside.com/pinball/forum/topic/pop-bumper-fires-with-flipper-activity/page/4#post-2401719

Beyond that list if you had a way of cleaning your harness of the carbon powder these machines fill up on over the years the problem would go away.

The Bally Auxiliary lamp board uses different SCRs that work fine with LEDs. The Alltek board just wires in all those resistors for you but on the board, rather than at the sockets. This is why you have to run that one wire to the live power lead for the controlled lamps.

Embryon has metal guides.

For that weird scoring with the flipper, check the switches under the playfield that have a capacitor across the contacts. If they look original they will be dried out and will cause plenty of strange behaviour. If you get any bumpers or slings activating with the flippers there are more involved things you have to do to fix that but only if its a real issue.

This is a long thread, but this post is a good summary to explain phantom firings. https://pinside.com/pinball/forum/topic/pop-bumper-fires-with-flipper-activity/page/4#post-2401719

As these machines are used, the conductive blakc metallic residue from the coils impregnates the wiring harnesses. Electrical coupling between the power wires and the switch matrix wires keeps getting better and better until misfires happen more frequently. The ideal fix is to wash your wiring harness.

The diode number I don't have handy but will appear in quite a few threads.

Some things to try, look at the pop bumper firing thread and follow some of the steps for solving the issue. Add caps to the flipper buttons, unbraid the head wiring as much as possible. Pull the lower playfield fuse which disables the coils but leaves flippers alive, does it still score? If it stops it is coupling in the wiring beyond the fuse. Then find the things that score 3000 and then look at the switch matrix to see if there is an area of the harness in common with the issues. Definitely scan around for more switch caps that are old. There are many that are not on the schematic.

I would normally use a ceramic disc style cap to avoid issues, they are non polarized. You can use the one you have just measure the voltage on the switch to get it the right way around.

Anybody on the latest CPR playfield list? I put my name on the list months ago and I know they are now shipping, I don't want to miss out. This is my first time buying something from CPR how does this normally work?

On any old Bally I have worked on, there have always been way more switches with capacitors than shown in the manual. Anything that involves ball hits (standup targets, roll overs, pops, slings).

You are correct about drop targets, I actually wrote standup targets. Slings respond better too however with caps. Mechanically a ball compresses a slings rubber for quite a while so they don't need caps as much. I have more than one Bally that had factory caps on the slings however. If you put a scope on the strobe lines, they are only being read at ~ 120 Hz, it is pretty slow, so they are refreshed every 8.3 msec. The actual window of time that the switch can respond is at best 5% of each 8.3msec window. So 95% of the time the switch is not being monitored.

Even with caps it is not all perfect, get a game like Xenon where the ball can rattle between pop bumpers for quite a while. You will get 20 bounces in a row, then the machine misses one, there is a slight pause, then it starts throwing the ball around again.

Had that exact issue on my Flash Gordon. It took quite a while to find. I originally thought it was the kicker head hitting the ball off center which I have had before. Then I replaced the coil sleeve assuming it was just too slow. In this case it was the drain switch wireform, it would not go down enough not to lift the ball slightly. It has a lower limit and if incorrectly set it can hold the ball up a bit. If the ball sat in the "U" shape at the bottom of the channel waiting to be kicked and got over the wireform it would push out of the way to the left (when looking from behind), let the ball sit down properly and get kicked correctly. If it entered just so, the ball could lean on the uphill side of the "U" and on the wire form holding the ball up just a bit. The ball would then be slightly to the left when watching from behind waiting to see it get kicked. The ball movement had enough wobble to not make it over the hill. On my FG, it would occasionally misfire, then sometimes have to try 5 times in a row before it succeeded.

Can you do it with the playfield up? If so, let it stick, then try flexing the flippers base plate in the middle, does it snap back? Linear flippers can bind up. I play with bending the base plate until the problem is fixed. Don't use a lubricant, it would probably grease it okay but upon retracting it would be slower.

If you have not done this before, as you pull connectors check that one pin on each has a plug in the hole. It will correspond to a missing pin on the board header pins. If that is the case you can confidently pull off connectors knowing you will only be plugging them back in the correct spots. On EBD, there should be a rectifier board in the base of the cabinet. One of those connectors harnesses up into the playfield as well. Then the play field lifts out no problem.

I would not file anything unless as a test before replacing the switch. A dirty EOS switch never cleanly shorts out the lower power coil. So during your power stroke, the low power coil is partially limiting the current to the high power coil, really slowing down the flipper speed and torque.

My understanding is the first level score works, the second does not? What about the third? One idea might be to switch the dip switches to a different game, set them. Then switch back.

Did you power cycle the game? It only reads the dip switches on start up.

1. Does it drop 14 credits for each game you play? Check the pricing settings if true. Otherwise very odd behaviour. Bally original machines are famous for not having a free play mode. Some people set the first score reward very low so you would almost always get a credit while playing.
2. Any Specials (Usually a red lit insert on a Bally) that are scored can be set to add a credit, free ball, or just points. Specials when obtained usually have the knocker go off.
3. Very common to need to reflow pins, but also many board ground through their mounts as well and that may be corroded.

Good point on the credits, a game is always 1 credit. But I did not see where he said he has an Alltek, or I missed it.