WPC 95 1 and a half beeps error.

[aurum]

Hi all,


I've got a Monster Bash pinball that's been in storage and upon powering up I had an initial error of 4 beep - indicating error in rom S4.


I removed the board and re-seated all roms and metered the roms and got all pins connected except the enable pin (22) - as expected.


I put the board back making sure all connections were correct and I now get 1 and a bit beeps. It's as though the processor is being reset about a quarter of the way through the second beep.


Anyone any ideas or suggestions?

Edit, could this be the WDT kicking the dog?

Mike.

[aurum]

Some progress (if you can call it that). after doing absolutely nothing except leaving it overnight the error has changed to 4 beeps indicating an error in sound rom 4. The rom is seated correctly and meters ok pin for pin with the other roms (bar the /E pin).


I'm wondering if during storage some damp has somehow caused problems. Has anyone come across this before? I'm going to leave it powered up for the rest of today to let it warm through and see if that helps.


If it turns out that rom4 has gone belly up, where can I obtain a rom image so I can burn a new one?


Mike.

[aurum]

I think I've found the problem. Although the batteries were removed a long time ago, it looks like the alkali wasn't neutralised.


The socket in the attached photo is for the 6809.


I plan to remove the socket and repair any tracks before replacing with a new socket.


Any hints and tips or things to avoid etc.


Mike.



 

[aurum]

A little more progress - socket removed. I'd forgotten how easy it was to desolder these old through hole boards - everything these says is smd and the tracks are thous wide. Think I'll leave the track checking until tomorrow.


Any hints and tips are still very welcome.


Mike.
Edit, the errors I was getting started becoming more and more random. I figured bad connection somewhere and then spotted the damage. Hopefully restoring the PCB to working order should sort it out. will keep you all posted.

[DSB]

Check out this youtube video. Looks similar to yours. This guy does some good work. If you don't get rid of all the corrosion it can come back on you.
https://www.youtube.com/watch?v=ey5e5ssnvfs

[aurum]

Thanks for that. It has confirmed what I suspected, I need to remove all the components with corrosion under them. The nice thing is that these boards are much more rugged than any modern board so easier to desolder. Plus, only two sided which makes it much easier to follow tracks etc.


Mike.

[DSB]

Also neutralise the affected parts with vinegar as you go.

[Strangeways]

Also check the ASIC socket. You will have to remove the chip.
Once you have the board working, consider NVRAM or mounting batteries externally.

[aurum]

After removing a few more components and an initial clean reveals many eaten away tracks. Think I'm just going to use wirewrap on the back of the board as a means of repair.


Mike.
Edit, any suggestions on what to coat the bare copper with?

[DSB]

https://www.jaycar.com.au/circuit-board-lacquer-spray-can/p/NA1002


You can use this to cover the tracks. It looks like it needs a bit more sanding with a very fine grit to get as much shine back in the copper as possible. If you sand through a track you can put a jumper in.

[Strangeways]

https://www.jaycar.com.au/circuit-board-lacquer-spray-can/p/NA1002


You can use this to cover the tracks. It looks like it needs a bit more sanding with a very fine grit to get as much shine back in the copper as possible. If you sand through a track you can put a jumper in.

+1

Use Isophrophyl alcohol to clean the area after your work is done - before using the lacquer.

[Retropin]

Corrosion is a bitch and would have gone beyond what is visible on the PCB... best of luck!

[aurum]

I've now cleaned the corrosion, replace the 6809 socket and socketed the 7414 and replaced the parts around it. I then put it back in the machine. It booted and reported it had done factory reset (no batteries so no surprise there). After 30 seconds it started resetting repeatedly and then died. I've now got a dead CPU board even though I am sure that everything was correct. Guess I'll leave it until tomorrow now as I'll have to rig up a bench supply for it. Does anyone know if just supplying 5V will allow the processor to run?


Mike.

[aurum]

Success, kind of. I reseated the PLCC chip and now it boots periodically. The chip and socket are both corroded. I've ordered a new socket of ebay but it'll probably take 6 weeks to arrive. Anyone know of a source in Brisbane for these (PLCC84 through hole) sockets? In the meantime I'm going to try a can of contact cleaner from Jaycar.


Mike.

[Retropin]

This do you?

https://au.rs-online.com/web/c/connectors/ic-sockets/plcc-sockets/?searchTerm=plcc%20socket