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Womble
8th June 2008, 06:44 PM
Have had some success repairing boards of late, one of my victories has been a Wonderboy bootleg.

The game landed on my desk with an odd fault. All sprites and icons were totally missing, the splash screen icons were all the wrong colour and the border was beige instead of black. Other than that it was great :lol

Someone had previously removed IC74 at 8M (an LS174), they had fitted a machine pinned socket and used half a reel of solder and a whole can of lacquer in the process. It was a globby mess, to rule out shorts I had to remove the lot. The IC tested ok so it was soldered in directly. One track didn't survive the process so a link wire was fitted. This didn't cure anything, but at least the board wasn't a mess.

I initially was certain that the missing sprites would be a RAM problem, I was wrong, all ram lines were busy, and piggy backing known good RAM changed nothing. So I went over the board with the logic probe.

Found an 74LS04 at 1N(IC97) had a floating output pin, piggybacking a new chip on it lit up the line and instantly restored the sprites. The old chip was binned and the new one soldered directly in.

The border was still beige and the freeplay splash screen sprite was blue, I could find no other missing pins, other than ones that could be explained by their datasheets (either not connected, or unused input pins on hex or quad chips).

http://i40.photobucket.com/albums/e230/Womble76/smallbluewb.jpg
http://i40.photobucket.com/albums/e230/Womble76/smallbluewb2.jpg

Finally found an LS157 at L10 (IC77) that when piggybacked made the start screen go nuts. Turns out that piggy backing on that chip will only take effect from a cold start. Chopped it out, soldered in the new one and the game is now 100% fixed.

http://i40.photobucket.com/albums/e230/Womble76/smallfix.jpg
http://i40.photobucket.com/albums/e230/Womble76/smallfix2.jpg

The large black space in the top left is where the lives remaining icons go, the board was set to free play so nothing shows up there until you find a extra life powerup. When not in freeplay that area has the 4 faces for the 4 lives.

The only problem now is that my wife keeps wanting to play it.

dav000616
9th June 2008, 02:00 AM
Hey Narf, definately a game worth repairing, seen a similar sprite issue if the sub-boards aren't seated correctly on wonderboy and choplifter.

Arcade King
9th June 2008, 08:35 AM
Good bootlegs though, will outlast the originals hands down.

well done!

staceyamusements
9th June 2008, 08:38 AM
How true.Also there are no custom chips to worry about.

Arcade King
9th June 2008, 08:39 AM
They do however suffer from track corrosion :(

Womble
12th October 2008, 06:23 PM
Another Sega Wonderboy PCB saved from the scrap bin.

Problem - garbled graphics, game runs but everything except the sprites is scrambled.

http://i40.photobucket.com/albums/e230/Womble76/wboy1.jpg

http://i40.photobucket.com/albums/e230/Womble76/wboy2.jpg

Fired it up, checked the RAM outputs with the logic probe, everything that should show activity was active. So moved onto the logic, and after 2 or 3 minutes burnt my arm on the RAM chips, these 3 were stinking hot. The 4th chip to the bottom left of the trio was barely warm to the touch.

http://i40.photobucket.com/albums/e230/Womble76/wboy3.jpg

Unsoldered them and it became clear how hot these had been getting, the board under each of them is pretty scorched, this board must have been left to cook for quite a while.

http://i40.photobucket.com/albums/e230/Womble76/wboy4.jpg

Cleared up the charring as best I could with PCB cleaner, didn't make a huge difference tho, fitted sockets, dropped in 3 salvaged 6116 chips and fired it up.

http://i40.photobucket.com/albums/e230/Womble76/wboy5.jpg

http://i40.photobucket.com/albums/e230/Womble76/wboy6.jpg

One happy Wonderboy PCB :)

One more board left to fix - that one has everything ok except the enemy sprites are totally missing. Logic weirdy somewhere I would think.

GameDude
13th October 2008, 07:57 PM
Nice work.... You gotta wonder how three would all die... My guess is overvoltage in crappy cabs.... Some things die sooner than others with overvoltage!

NateDizzle
16th July 2011, 08:05 PM
Is there a chance they could have been replaced with under-rated components previously? I'm not very familiar with logic and RAM at the moment, but is that possible? like replacing a 1000uf 16v capacitor with a 1000 10v for example?

vib_ribbon
26th July 2011, 10:03 PM
loving these write ups and successes in fixing the faulty boards. much respect on the time & effort spent on this cause!

wazza13b
15th October 2011, 12:42 PM
just spotted your thread i have a wonderboy bootleg that has problems too when plugged in it comes up blank screen when fiddling with chassis i get some sort of jumbled picture any ideas what could be the problem i'm not electronically good but all voltages are correct

Womble
15th October 2011, 01:15 PM
Not really - wonderboy bootlegs are horrible boards, the board in this thread actually was an original Sega, you can see the Sega logo in some of the shots.