MPU is on the bench. Only get one LED flicker on power up. Removed U2 and U6 and tested in another MPU and it booted, so I'm assuming U2 and U6 are good. Board did have some corrosion which I abated, replaced several components, including U8 socket. Suggestions?

Popped off the plastic upper on these two sockets and the pins looked good.
Also replaced U11 socket while I was there (found it to have a few corroded pins).

I found C12 broken while I was working on U11 (maybe I broke it). It is an axial cap, looks like a resistor. Is there some reason why this shape cap is used instead of a ceramic disc?

Yes

So after replacing U11 socket, and checking the pin connections, inspecting U7 and U2, and replacing C12 (with a ceramic disc), now I don't even get a flicker.

Yep, last thing worked on I replaced the LED. Found it in backwards. So fixed that and got 6 flashes on the bench. Installed the board in the game and got all 7 flashes but the displays didn't come on. Game went into attract mode but won't start a game. Pressed the test button in the coin door and was able to scroll through the menu, even some (not all) of the displays came on.

I had replaced the female pins on the MPU wires connectors. I'm suspecting I need to replace the header pins too. Could there be something to check before I begin that daunting task?

Took the board out and replaced all the header pins on the board, so all the connectors on MPU have been replaced, headers and females. Put the board back in the game and same thing. Displays are blank unless I do the self test, then they light somewhat. I put in my spare MPU and everything works fine, so I can deduce the problem is on the original MPU.

With the MPU on the bench I checked trace continuities around J1 pins 10, and 20-28. I believe I have a bad C58, as I compared readings to my good board. Also, I checked the voltages at U14, U19, and U20. Do these results suggest where the problem lies?

Screen Shot 2020-06-20 at 3.07.13 PM (resized).png

I don't have a test ROM.

Here's what I have done, maybe will shed some light on the problem: I took the U2 and U6 proms out of the board that is showing blank displays (although I do get 7 flashes on the LED). Put them in a known good board (jumpered for these proms), and get the same results....7 LED flashes but blank displays. To see if I have bad wiring or bad displays I installed the WEEBLY MPU and the game boots perfectly and all displays work. Hurray for the WEEBLY Universal MPU!

So, does this sound like a problem with the U2 and U6 chips? Would these cause blank displays after boot?

Can you confirm what ROMs these are? Are they 2532 or 9332?

36D976E4-DF80-4138-9FA7-B4C2C26AB0D9 (resized).jpeg

6B2D4B49-D888-40E7-96C9-A137069F7B6A (resized).jpeg

I uploaded a better pic. Yes, I see 2532 as part of HN462532. I'm never sure when it comes to chip nomenclature. I never think I'm going to fix a lot of MPU boards, but I have worked on a few. Still learning. I'll check into getting test ROMs.

All three balls are there. Even in the test mode, the display test shows mostly blank displays.

Sure. After the 7 flashes, and all the drop targets reset, etc., and all the displays are blank.

I drop a coin in and 3 credits show up. That is the only display now working....the Credit display. I press the credit button and nothing happens; still showing 3 credits.

Press the test button in the coin door and all the lamps test ok.

Press again and all displays are blank EXCEPT for display #1. It is only showing digits in the ones and tens space. It is showing 11, then 22, then 33, etc...., not 1111111, 2222222, 3333333, etc. as you would expect. There are occasional flickers of single digits in the other displays as the test cycles,

Before I do that, can you tell me what difference does it make? When I install a known good MPU everything is fine. When I reinstall the original board, this is when the displays don't work. I have about 165V at TP2. The displays are only not working with the original MPU, and another MPU using the same Game ROMs taken from the original board.

I do. I have pulse activity on all those pins.

Stated/restated: I have 3 MPU's I have tried in this game. One is WEEBLY Universal MPU. I put it in the game and everything works fine.

The other two MPUs are Bally 2815-35's, both jumpered identical for original factory game ROM's (U2 and U6). I only have the one set of these ROM's.

When I install either of these Bally boards in the game, swapping the U2 and U6 between the boards, I get the same results.. no displays, except for how I described in post #19.

Could both boards have the same defect? Or could the U2 or U6 be bad causing the problem(s) I am having? What more to test?

I typically run a lower voltage to save some life on my displays. Anyway, I raised the voltage to 190. No change.

I disconnected J2 and J3. When I went into test mode, there were no displays at all.

I reconnected the J2 and J3, rebooted, no balls in game, all targets up, and went into test mode. The display was blank on the switch test page.

Plugged J3 back in. Started the test then unplugged it. So difference. No displays.

The displays that do light are the same as the combo board.

Here they are....

IMG_5197 (resized).JPG

IMG_5198 (resized).JPG

Yes, good connection. Same on both non working MPU's

No. Interesting....what happens end of boot, solenoids reset, game goes into attract mode, lights flashing, then the attract mode lights quit flashing after about 5 seconds. Won't start a game and no displays.

No.

Here is the link to the video.

No, I am only swapping the U2 and U6 ROMS, and both boards act the same.

I did this. No difference.

I did this. No difference.

OK, I will take the ROM's from my Rolling Stones. Question first, do I need to change the jumpers on this board in test for the Stones ROM's to try this?

Quench: Before I remove the Rolling Stones ROM's for this test, could I install the working Stones board in my Fathom to see if the displays light? Would this tell anything? Then I can remove the ROMs and put in the board that is not working and try that.

I did this. Installed Rolling Stones working MPU in Fathom. Disconnected J4 form solenoid board as well as J1 from the sound board. No change. The displays don't come on. They flicker once during the boot, but remain off. So does this suggest the problem lies somewhere besides the MPU?

I have 190V and 5V respectively on TP2 and TP1 immediately on powering up the game. Also confirm that all the displays are 7 digit except for the credit/ball in play which is 6 digit.

Here's the results:

DATA #4 (resized).png

I had the probe connected to 5V on MPU (TP4 and TP5)

Here's another video of something I learned. After the attract mode ends, and before trying to start a game (can't actually start a game), there are no displays. I learned that if I press any switch, target, etc., the #1 player display starts showing points and doesn't stop until somewhere around 1,250,000. If I touch another switch it takes off again....goes into the millions of points.

I am not hooking up a battery.
I bought a supply of 5101 chips from overseas a while back. I guess they are not genuine. They were inexpensive. I could take one from another working board and try, but not sure if they are genuine or not.

Yay!!! You got it! Hooked up a battery and no change. Replaced the 5101 and everything works!
Unfortunately, all my old Bally games/boards have the same "counterfeit" 5101's except one. Guess I lucked out on the other games, but now I need to find a supply of genuine chips. How can I tell real from fake?

Of all the board swapping I did, the ones that didn't work were those that had the 5101 with the '50 year stamp. I had purchased those 5101's off eBay about a year ago from China. Little did I know.

I had a rebuilt 2518-35 MPU spare board that gave me 6 flashes on the bench, 7 with the jumper test, even though it had one of those bad 5101's. I also had the MPU that came with this Fathom I just purchased. It had corrosion so replaced the U8 socket and installed a new 5101. Another bad chinese version. It gave me 7 flashes. So I was working with 2 boards that gave me 7 flashes but didn't boot correctly.

Checking what I installed on my other games, my Rolling Stones has one of the chinese chips and it plays fine. Don't know why. The only difference, maybe just coincidently, is that the Rolling Stones is running a modified -17 board to emulate the -35 board. For whatever reason, it's working.

I'm ordering some "real" chips and tossing these headaches!

Yes, again, thanks Quench. Can't say it enough....thank you.