I am looking for some help with an issue that just cropped up on my Xenon.

I resoldered a loose connection under the playfield on one of the pop bumper light sockets (the power to the machine was turned off during the work) and upon attempting to restart the machine, it boots fine and calls out "Xenon" when the credit button is pushed but the number of credits is not reduced and the game does not start. Upon pushing the credit button a second time (or third, fourth, etc.), there is no response (it is "locked up). Additionally, the diagnostics button works after rebooting but will not work once the credit button is pushed, "Xenon" is called out and no game starts (it is also "locked up").

I have swapped out all of the socketed chips with a set known to work and I have used a TwoBits Pinball Fixit board in place of the game ROMs, all with the same results as reported above. Thoughts?

I have an MPU from and EBD that was working fine and then locked on (no flashes, just a constant-on LED). I replaced it with an Alltek MPU but I have been working on the original board trying to get it working. I tested all of the socketed chips (6800, PIAs, 6820 and 5101) in a working MPU and they are all fine. The reset section is working fine (voltages check out on the 6800 and pin 40 goes low when shorting the resistor junction to ground in the reset section). I went to a shotgun approach and replaced every chip and all of the sockets on the board, but it is still locked on.

I put the board on the bench next to a working AS-2518 and powered up both at the same time so that I could check voltages and probe outputs for each one. I have discovered that pins 10 through 19 of U11 on the locked board are dead (no reading with the multimeter nor the probe). Thoughts? Any help would be appreciated.

All sockets were removed/replaced and all of the unsocketed chips were removed, sockets installed, and new chips installed.

Go to greatplainselectronics.com and get this crimping tool: https://www.greatplainselectronics.com/proddetail.asp?prod=W-HT-1921

Go here: https://www.greatplainselectronics.com/categories.asp?cat=7 for pins, housings, contacts, etc. Ed has it all.

No MPU gurus out there???

I have seen a number of them with failed SCRs and decoders. If they aren't working, but have a dim glow at the very least, they most likely can be fixed. The SCRs are easy to test with a digital multimeter and the decoders are cheap and easy to replace (be sure to install a socket). Lastly, turn the voltage down to about 170 vdc (there is a pot on the solenoid driver board that can be turned counter-clockwise to reduce the voltage) and they will last a lot longer with no noticeable reduction in brightness. If they flicker with the reduced voltage, turn it up slightly and they'll be fine.

Have you tested the diodes at CR5, CR6, CR7 and CR8? Per the schematic, those are the rectifying diodes in the circuit with with F3. One of them has possibly gone bad.

Here's a -35 MPU question: I am working on several in an attempt to learn and hopefully bring them back to life. I have replaced the MC14011B IC at U19 with an HEF4011BP. Is that the proper substitute? I reviewed the datasheets and it appears to be a drop-in replacement, but when I do the "diode test" (red to ground and the black to each of the legs) I get different readings for several of the legs (note that I have a working -35 that I use for reference).

Thanks in advance.

Does anyone have a pinout chart for all of the ICs on a -35 MPU that they would be willing to share?

Chasing every IC pin connection through the schematics is a ton of tedious work. If someone has already done it, why recreate the wheel? I am just inquiring if there is a fellow pinsider who is willing to share the fruits of their hard work. If not, I'll go back to the schematics. Thanks in advance.

barakandl, are you ever going to offer a -54 rectifier board? Your -18 board is awesome.

The -54 board is fairly straight-forward to rebuild if it isn't burned up.

I just completed refurb work on a Xenon, but it has an intermittent flipper issue that I can't figure out.

The left flipper works fine, but will periodically stay "flipped" (won't return to the resting position) even when the flipper button is not depressed. It is an electrical issue, because it releases if the power to the machine is turned off. The EOS switch is clearly open when this happens, as is the flipper button switch. I have done the following:

* Metered the coil. It is good and the flipper works quite well until it gets "stuck" open.
* Replaced both diodes on the coil. They are installed in the correct orientation.
* Resoldered all of the wiring to the EOS switch and the coil.

Thoughts?

You should be able to go to GPE and order all of the individual parts that make up the kit. A link to a parts listing is available and Ed should have the parts in stock. Big Daddy is certainly an option if you want a ready-to-go kit.

No amount of hitting the button will release it. Only turning off the pin. I will try a different coil stop.

Swapped the coil stop from the ball kicker, which appears to be nearly-new. Same issue. Connectors at the solenoid driver board maybe? The flipper power just passes through the relay, but could bad connectors cause an issue?

Found it. It was a self-inflicted problem. I used an automotive points file to clean up the contacts on both flipper switches. There were enough filings on the left one to provide a very weak trace between the switch contacts, which would occasionally provide a path to ground and cause the left flipper to stay in the hold position. I cleaned out the filings and all is good.

Help! This is driving me crazy. I rebuilt a -54 rectifier board (I have rebuilt several others with no issues) from a Xenon and TP3 is reading over 30 vdc. The board had some prior work and still had the original 3 amp diodes for the 12 volt rectification. I tested it before I started and it read about 15 volts at TP3. I replaced the original diodes with 3 amp 1N5404 diodes.

I have done the following:

* I reflowed all of the connector pin solder. There are no shorts in any connectors (tested with DMM).
* All of the 5404s pass the diode test (they are all new).
* I can detect no shorted traces anywhere on the board (tested with DMM).
* Confirmed about 15 vac at the unbanded ends of CR6 and CR7.
* Got over 30 vdc at the banded ends of CR6 and CR7. Cut the trace to TP3 and still got over 30 vdc.

Help!

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I started a new thread for this issue:

https://pinside.com/pinball/forum/topic/bally-54-rectifier-board-12-volt-problem#post-4945127