PDA

View Full Version : Wonderboy fault



humpalot
12th June 2009, 06:34 PM
Have a graphic fault with a wonderboy in that no sprites show. Game plays correctly with proper background graphics etc.

Any idea's where to start?

Would love a schematic.

Beast
12th June 2009, 07:22 PM
Would love a WonderBoy :redface

Arcade King
12th June 2009, 07:25 PM
is it bootleg or original? if bootleg id be looking at the big rider first and possibly ram.

humpalot
12th June 2009, 07:27 PM
is it bootleg or original? if bootleg id be looking at the big rider first and possibly ram.

:cry it's an original. Do you suspect the custom there?

Arcade King
12th June 2009, 07:38 PM
are you handy with a probe? id be checking around those customs for starters and anything connected to them.
think ive got a scrap Sega system "A" shinobi which I "think" used those customs that your welcome to.
Look for any "F" chips also. Basically look for anything dead or stuck high or low.

humpalot
12th June 2009, 08:13 PM
Thanks AK.

:( I hate playing around with arcade PCB's.

VectorGlow
12th June 2009, 08:21 PM
From my own Wonder Boy repair log:

Symptom: All sprites are a thin vertical line, or not visible at all
Cure: Bad outputs on the LS175 at location IC91, particularly pin 3

Not saying it's that chip at fault on your board, but it will give you an idea of the area to look at; check the I/O on that IC anyway, then if that's okay work around the ICs feeding it signals and what processes those that it spits out.

Arcade King
12th June 2009, 08:24 PM
Customs are usually pretty hardy on Sega boards (except Sega system 18 :b) I think everybody will agree a board worth saving. :)

VectorGlow
12th June 2009, 08:28 PM
Most definitely. A lot of people love Wonder Boy, more especially the original boards.

Womble
12th June 2009, 09:48 PM
I would instantly suspect the 74ls04 chip at location 1N, ie ic97.

Have seen that chip cause the exact same fault! Piggy back a known good 04 on top of it to test.

humpalot
12th June 2009, 10:08 PM
I would instantly suspect the 74ls04 chip at location 1N, ie ic97.

Have seen that chip cause the exact same fault! Piggy back a known good 04 on top of it to test.

Thanks I'll look at that and LS175 at location IC91 before going onto and checking what AK suggested.

Just find arcade boards with no schematics too time consuming.

The thing only died yesterday one of my fav games. If I can sort it out I might look at the other 3 wonderboys I have in the pile :lol (all bootlegs)

Arcade King
13th June 2009, 07:30 AM
As Womble suggested piggy backing is your friend :) even if your not good with repairing boards piggy backing a known good chip on top usually works.

humpalot
15th June 2009, 06:58 AM
All RAM chips good, custom chips appear OK, the 2 74 series IC's mentioned also test good.

Womble
15th June 2009, 09:52 AM
Do you have a scope? Its going to be either a stuck pin on a TTL or a floating output. Continuity test to where the 4 outputs of the LS04 go, then check the outputs of those chips. Something somewhere has lost the plot, if the board is full of F chips then it can be easy to spot as the outputs just get disconnected, so its neither high or low.

humpalot
15th June 2009, 10:30 AM
No F chips on the board. I'll have another play with it tonight checking around the 04 chip.

Womble
21st June 2009, 01:19 PM
F chips tend to die by losing pins, the output pin of a gate often is neither high or low. Other brand chips tend to end up with an output pin stuck high or low, which is harder to spot than a floating pin.

humpalot
21st June 2009, 01:39 PM
F chips tend to die by losing pins, the output pin of a gate often is neither high or low. Other brand chips tend to end up with an output pin stuck high or low, which is harder to spot than a floating pin.


A schematic would make things easier. Trying to compare a working bootleg to troubleshoot the original, have identified about 4-5 chips that have outputs stuck high or low.

Just had a knee op and my head is spinning from the drugs :lol Hope it makes sense :blink:

humpalot
23rd June 2009, 06:49 PM
OK my head is clearing so spent sometime on this today and have done a fair amount of reading up on net trying to find info about these boards.

Have located some 74 series IC's with no input signals, these signals should be coming from the custom chips.

Will now be going back over the two custom chips at IC111 and IC118 (first mentioned by AK). These two chips generate the sprites, which is what I am missing :redface

Womble
23rd June 2009, 07:17 PM
Its never good when you trace inactivity back to a custom, however it is possible that the custom is missing some of its inputs too.

humpalot
24th June 2009, 06:55 AM
Can confirm both customs are working correctly.

However found one of the legs on one of the customs had no solder. Soldered it up and now have what looks like a dark shadow go across the screen, this shadow is the sprites.

Hmm still need to do more work :cry

Arcade King
24th June 2009, 05:51 PM
can you take a pic mate?

humpalot
25th June 2009, 01:15 PM
can you take a pic mate?

Went to take a pic and bloody thing was no longer doing it :realmad:

humpalot
25th June 2009, 02:07 PM
Been busy probing today, ended up going back to my old HP probe, so much easier to use.

Found 2x faulty IC's at locations IC70 and IC81 both chips are 74LS699.

Replacing these chips restored missing signals to IC44, IC59, IC60 and IC99.

Still don't have sprites, have located missing signals to the 2148 ram chips located at the top of board along with 3 IC's which are also missing signals in the same area.

Still more work required, but almost there.

humpalot
27th June 2009, 09:42 PM
Happy to say that the board is now repaired :p

Would hate to think of how many hours I spent on this repair.

Can confirm the following faults were found and repaired on this board.

Custom chip at IC118 had no solder on one leg.

IC3 a 74LS244 was bad.

Very interesting this part was that all 74LS669 IC's on the board were bad. All these chips were Mitsubishi brand and were at the following locations. IC51, IC56, IC68, IC70, IC79 & IC81.

VectorGlow
27th June 2009, 09:52 PM
Well done on the repair. :)