Hey everyone!

So I am still working on a ghostbuster Pro that had a bunch of issues light related.

All the non working lights and flashers were all on the same circuit which went back to the node8D board on the bottom left of the under playfield. So after checking all the bulbs and checking the power on the board and seeing that everything was right I thought that the logic part of the board must be dead and so I ordered a new one. But after install, the same lights are still not working.

I found this post and followed the instructions but still no luck.
https://pinside.com/pinball/forum/topic/trying-to-fix-a-flasher-on-stern-spike#

The guy ended up changing the board anyway and that didn't help me.

I checked the cn1 cable that runs the data from another light pcb and it does seem to connect. Only the MISO pin does not trace from cn2 to cn1 but looking at the board this seems fine.

Any ideas?

Sunday bump.

Hey everyone.

So after some more tinkering and after reading up on the spile system and more precisely the MOSI MISO lines I decided to try and short the MOSI MISO pins on the node8D and the whole array of previously dead lights and flashers turned on.

I'm not really sure what to make of it. Is it a signal issue?
The other light arrays seem to be working fine so probably not a problematic node 8 right? Same for the node 8D, if I get light when I force the signal to be on it should be good right?

Any ideas?

Alright so to add to the mystery, I decided to bypass all the light pcbs up to the node 8D board and plug the 5v/MISO/MOSI/SCK/RCK cable directly in the node8 board. And it worked perfectly...
So since the cable is good and the pcb is good it means I loose the data line on the board8C. But there are no schematics online for that light board.
Any ideas how I could identify where I loose the data?
I already looked at the traces and components and nothing seems fried. Also the board 8c works perfectly fine so I doubt anything is fired.
Should I just connect CN1 to CN2 myself on the board 8c?

Yeah I have to say I'm not a huge fan either. I hate the fact that there is very little you can do to fix these newer pins yourself. Two Spike pins on location and already two node 8 boards down... Nice profit.

Thanks for the bump ! However, the Node 8/9 boards are working fine for now (already replaced one) the board I changed is a small one responsible for 16 extra lights. It's deceivingly called node 8D in the manual but it really is just an extension board. See link https://littleshopofgames.com/shop/boards/stern-boards/serial-16-led-board-for-stern-spike-pinball-machine-520-6831-01/
I already swapped that one out but it does not seem to be the problem.

Thanks for the suggestion but I do not think this is possible. The board has very little logic in it and does not show up in the menu (see link above).
I think the problem comes from the other light board not transmitting the signal (board https://www.marcospecialties.com/control/keywordsearch?SEARCH_STRING=520-6992-00) because if I bypass it and plug the led 16 driver straight into the main node 8 board, everything works fine.
The thing is I cannot find any schematics for that one (schematics for the led 16 driver are available but the board seems fine) so I can't really figure out where the signal stops.

Thanks man ! Yeah I thought I'd explain my thought process, might help someone later on especially if I manage to resolve the issue.

Hello everyone,

I think I figured it out ! Strap on for the ride, this one's a doozy.

So, not finding any documentation about the light board 520-6992-00, I decided to try and reverse engineer it. Long story short, on every light board that are daisy chained together, the component pattern before sending the signal out to the next board is the same. And that pattern is documented on that file: https://sternpinball.com/wp-content/uploads/2019/02/520-6831-00B-16-Output-LED-Board.pdf
Basically the MOSI signal goes into a few ICs (74HC595D or 74HC594D depending of watchdog presence), then it passes through a double inverter twice with a few resistors and caps in between (pattern can be seen on 520-6832-00B schematics above on the bottom right corner between pin 9 and CN3).
While checking the components in this pattern, I focused on the NC7WZ14P6X inverter present on every light board in the pin. (doc of the inverter : https://rocelec.widen.net/view/pdf/9bas6aien1/FAIRS31607-1.pdf?t.download=true&u=5oefqw)

As seen on the datasheet, only pin 2 is grounded and pin 6 and 4 are the outputs of pin 1 and 3. However, on both of my broken boards, pins 6 and 4 (the outputs) are also beeping in continuity test (like pin 2 which is supposed to). When reproducing this test on the 3 other working light boards on the pin, the only grounded pin is, you guessed it, number 2.

Now this isn't conclusive evidence until I actually swap them and get the board working, but the actual inverter is HELLA small.

Anyone has any advice? Should I try to change the component or is there any chance that the outputs pins are grounded by default and my issue is somewhere else?