Not up to Vectorglow and Wombles standards (or level of tech knowledge) ....I'm afraid...but still useful to have in your repair log area I think none the less.
Got a NBA Jam (Rev. 3) board 'quite' cheap (under £38 posted which is getting hard these days) from the states, and he kept the value under $15 dollars or whatever so I didn't have to pay customs charges.
It came with an original manual and a felix marquee (also original) the guy who sold it to me said that it worked but flagged up in the test part as you boot it up that UJ11 is bad and because of this it keeps resetting itself.
Came with no loom between the two boards, other than the ribbon cable (Phew! didn't want to have to find/make that one) so I made the rest of the looms it needed and wired up a pot for the sound, couldn't find a cheap 50k one so used a 47k one from Maplins.
I got the board and fired it up, at the end of the boot up test all the chips come up green and check out ok, but sure enough on the next screen it said UJ11 BAD cannot restore factory settings, and using dip coinage instead.
If I pressed start quickly after the board has just booted up then (due to it being stuck on freeplay cause of the dip settings) it would work fine, played a full game no problems at all.
However once the game ended as the demo goes to run, it resets.
Well you can't leave it running in a cab like this...
I tried to enter test menu to mess about, and it basically said "Can't enter service menu due to CMOS UJ11 bad unable to restore factory settings"
So this time I booted it up (and I didn't start a game) to see what it was doing, it loaded the title screen but again just as the demo loop goes to start it crashes and resets the board back into the test.
Looked at the schems online to locate UJ11
I've circled it red in the picture attached.
The schems said:-
Part no. 5340-12558-00
Part Designator:- UJ11
Description:- 5565
With a bit of help on U.K Vac and Jamma+ they told me it was a CMOS ram.
The chip on the board was a Sharp LH5168-10L after not finding a spare on any of the dead boards I had, I ordered one from China.
I fitted a socket just to be paranoid, then fitted my brand new cmos/ram in place, fired it up and it was the same
Lost heart for a few days so chucked it to one side, then had a brainwave or two whilst watching t.v and decided to have another look.
First pulled both 'version' roms i.e the two which hold which version it runs, rev 2 or rev 3, checked them against mame and they were 100% identical.
Then checked all other roms, must be like 14-16 roms, took a while, guess what all spot on.
Just before I fired up a scope to try to pretend I know how to use it
thought I'd just have a re-think.I noticed as it reported UJ11 bad it said now going to use dip settings instead, so I checked the dips and they were already set for cmos, so then I took it off free play and reset the board, still came up as bad agan, but then tried to enter test mode, this time it let me in the menu...progress!!
I changed some settings and reset the board, next time it booted it said that it had loaded the factory settings into the new CMOS as it then worked, played the demo and was spot on.
It looks like to me although I had replaced the faulty CMOS, all I needed to do was enter the test menu, change something/anything and reset.
This then dumped settings across into the CMOS which then fixed my problem by giving it some basic settings again.
So remember if your CMOS ram which holds all the settings goes bad on a MK, MK2 etc... or NBA Jam/TE or some other MIDWAY board of that era, and you need to change it, go into test menu once your done change something then reset, this will then fill up the new ram with some info which it then can retain.
My guess is the reason it resets with a bad cmos and won't run the demo as it has no scoreboard info maybe.
Don't confuse all this with the battery BR2325 onboard which also helps hold changes in the settings/coinage, my problem was more than that, I've had the battery error before on Mk1/MK2 etc... the board will still run and not reset with a bad BR2325 battery just won't hold certain settings after a power off.
My fault in the boot up test was the actual cmos/ram chip at UJ11 which holds the actual factory settings for everything. It reported UJ11 CMOS BAD "unable to load factory settings"
Thanks for reading a newbie report, as I say not very "techie" but if it helps one other person not loose some hair it was all worth it.
Ta
Paulous.
