World Cup 90 Euro League (Bootleg)

[Jacmar]

Had a bit of spare time to look at this for another forum member .... arrived with the usual layer of dust which when cleaned off showed a board in decent overall condition... no obvious damaged traces or signs of previous repair ... described as having graphics issues ... and after checking for shorts, then booting up, it certainly did ...



First obvious problem was the colour, the blue wash over everything (it was lighter IRL the camera makes is look much darker) sent me looking for the palette ram. Didn't take long to find all 4 outputs of the 2148 ram floating, despite good signals on all other pins .... quick piggyback gave me a green pitch so out it came and got replaced ....



So now we've got good colours and can see clearly there is obviously sprite issues (which I decide to leave till later) as well as broken background scroll layer positioning ...

Traced this scroll problem to a bank of 4x LS374 latches near to the graphics RAM chips and ROMs. I'm thinking they probably latch horizontal/vertical scroll coordinates or related tilemap address values. These then feed 74LS283 adders and 74LS153 multiplexers, possibly forming part of the background tilemap address-generation circuitry ... Either way, several outputs showed stuck signals. Piggybacking three of these 374's improved layer positioning but I thought it unlikely 3 or even all 4 were bad. I decided to remove and replace the 2 that gave the best results when piggybacking (one removed the people in the stand and the other put the goals in the right place) thinking as they were all connected to each other (pairs share outputs and /oe) maybe one or 2 bad ones were poisoning the whole bank ... so removed the 2 on the left shown below ..



And it did permanently fix the crowd and the goals into the right place, but still had the scoreboard in the wrong place and worked out I actually had the top half of one layer in the bottom half of the screen, and no bottom half visible anywhere ... as you can see from the attract sequence high score table, and the character layer during the game...



Piggybacking a 3rd one of the LS374's would move the scoreboard all over the screen so I decided to remove that one and while I was there thought I might as well replace the 4th one too to make sure ... if 3 are bad then, as they are all the same make and batch code, it's likely the 4th is too or will be soon. So out came the other two IC's ..... in the end all four of those needed replacing to fully fix all the layer positioning errors .....





So that's the layer positioning all sorted and I'm thinking OK just the sprites to fix now .... nope ... it's now that I can see more of the writing on the screen, I realise there is a palette issue in the character/hud layer ... you can see the difference below between the board (left) and what it should look like (from MAME)



Traced this to a bank of 3x LS174's ... possibly registering character pixel data, palette-selection bits, or other video information. One of these had a bunch of stuck outputs and again a quick piggyback gave a couple of colour changes in the layer in question. the match timer background changed from green to red (still not correct but it changed!) and the 'INSERT COIN' text turned white (correct!) ... I confirmed it well and truly bad with a SLICE test .... and so it got replaced ....



And that fixed that



So NOW just sprites to sort ... (continued in next post) ...

 

[Jacmar]

The sprites issue looked like a classic bad line buffer ram, every other line of each sprite missing .... these often work in pairs like this so one can draw while the other is prepped ... and so over to the pair of 6116 ram I go. And no surprise that one of them has dodgy floaty looking signals on its data pins .... That's it, almost done! Convinced I've cracked it, I whip it out (the IC !!!) and get a replacement socketed up thinking job done ..... but no it's not ...



It's just exposed another issue that I couldn't see before because of the bad ram
Some missing sprite pixels have returned but are now scattered randomly all over the screen...

Didn't take too long to work this one out, and this is one of those situations where SLICE is so good ..... The random pixels only appeared when the new ram was in the socket, so I knew the problem was on this net somewhere, I checked the address pins of the new ram in socket and signals looked good, traced them to the outputs of a bank of LS163 counters, again signals LOOKED good (as in healthy toggling signals) but doesn't mean they are correct .... this is where the slice is such a brilliant piece of kit .... below you see the difference between a working LS163 (left) and a bad one (right) and despite the fact that visually on the scope the signals on both looked healthy, slice clearly identifies the bad one !!



So with zero hesitation the bad LS163 was removed and replaced and this restored the sprites 100% ....





And that finished the fix for this board .... quick summary :

replaced 2148 Palette Ram - restored correct global palette
replaced 4x LS374 tilemap latches - restored correct layer positioning
replaced LS174 - fixed palette error in character/text/hud layer
replaced 6116 sprite line buffer ram & LS163 counter - restored sprites

(replaced IC's marked in blue below)

 

[Flyback2021]

Great Work and write up as always !

 

[qjuk]

Nice fix, and again another detailed write-up

Like you said, SLICE is a great piece of kit and a fantastic tool to have in your armoury.

 

[Jacmar]

Cheers, Love my SLICE

Interestingly if you look through the pictures in order in this thread you'll see when I first booted the board, the sprite line buffer ram and the LS374's were working because you can see the scoreboard/crowd in the correct place and the random sprite pixels .... but that initial boot up must've been too much for the LS374's which failed shortly after, sending the scroll positioning haywire. Then at some point while diagnosing and replacing the LS374's the random sprite pixels disappeared, so that was when the ram chip failed. Shows again how in the process of fixing a board that's hardly been used for potentially a number of years you often inevitably create more problems than you start with !