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Wonder Boy in Monster Land Bootleg - NO RED


Grish

Question

Hi All,

 

Red on my WBML board seems to have died, I have no idea even where to begin with this, I can rule out the cab/monitor being an issue as other boards work fine.

 

I traced continuity about as far as I could from the red pin on the Sega System 8 connector to a resistor, then other side of resistor it runs all the way over to the other side of the board and finally hits up a chip: GD74LS174 which is apparently a "flip flop" - This is as far as I've gotten.

 

Before I guess to much, I was hoping loss of an RGB colour would be something fairly common in the arcade pcb world and someone might have a cheat sheet or idea of where to look?

 

A few pics of the issue and the board over on this board: https://forum.arcadeotaku.com/viewtopic.php?f=2&t=27247&start=100

 

Any leads would be so appreciated!

 

Cheers,

Grish

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Tracing it back on my board, red goes through 2 resistors and a resistor pack. Prior to this, it outputs from pin 2 of the 174 at IC154. Probe pin 3 of this which is the input. It there's activity on pin 3 but pin 2 is high, low or floating, change the 174. If it's low or floating, you can piggyback another over the top and see if red is restored.
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Tracing it back on my board, red goes through 2 resistors and a resistor pack. Prior to this, it outputs from pin 2 of the 174 at IC154. Probe pin 3 of this which is the input. It there's activity on pin 3 but pin 2 is high, low or floating, change the 174. If it's low or floating, you can piggyback another over the top and see if red is restored.

 

Great, thanks for the lead, I don't have a probe or any other tools other than a dmm.

 

When you say piggy back, does this mean bridge a wire to a neighbouring 174? And which pin/s would I bridge?

 

Sorry for the noobish question, but I really am a noob :)

 

I did pop down to Jaycar and pick up a couple of 174 and 175's. So if there is a way to test with a piggy back prior to replacing, that would be handy.

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Piggy backing is simply placing your replacement IC on top of the existing IC, placing each leg directly onto the equivalent leg of the suspect chip. Like a parent giving a child a ride on his back.
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Piggy backing is simply placing your replacement IC on top of the existing IC, placing each leg directly onto the equivalent leg of the suspect chip. Like a parent giving a child a ride on his back.

 

Oh god! I wish I saw this before butchering, burning, breaking 1 or 2 traces and resulting in hacky wires on solder side... That was just me attempting to replace the LS174, which didn't bring back the red. It was next to impossible to remove with my lousy solder sucker and chunky iron, the orig chip ended up in pieces.

 

And I've managed to make things a LOT worse, now the top half of the screen is repeated on the bottom half!!! Nooooooo :(

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Quick update:

 

Red is now working, so the original problem I had is now fixed. It was a dodgy resistor meant to be 100ohms, but was reading 1Megohms! - Swapped it out and bingo back came red!

 

However, the other problem that I somehow managed to introduce while stupidly replacing the 74174 chip is still there, the top quarter or third of screen repeats itself in lower part of the main gameplay window (wonder boy has a "border" along top and left side, which is not affected) these pics say 1000 words anyway:

 

I know it's nothing to do with the PROMS and I'm now suspecting RAM, take a look at pics and if anyone has any clues please chime in!!!!!

 

1_red_get.jpg

 

wtf2.jpg

 

wtf.jpg

 

This next part is VERY interesting, the problem doesn't show up on the credit screen if you credit up BEFORE the game demo runs....:

 

credit_screen_before_demo.jpg

 

After game demo has ran:

 

credit_screen_after_demo.jpg

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I would once again remove the chips you replaced and start over, checking every trace to make sure they're connected.

Check the pad where the trade meets. I'm assuming you socketed the chip, and using standard sockets, you may have a trace not connected which you can't see underneath the socket. So yeah, take out all the chips/sockets you replaced and take photos of where the traces go. Use machine pin strips instead of a socket, and after you've soldered them in, check continuity to your photos to make sure they're going where they're supposed to.

BTW, if you don't have a decent desoldering gun, you'll risk damaging the board even more. If you don't then cut the legs of the chip and removing them one leg at a time. ICs are cheap enough to sacrifice.

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Thanks for all the awesome tips holy-snes, I have spent quite a lot of time tracing each of the 8 legs from the replaced 174 chip, I had damaged the board and needed to use little jump wires on solder side to rejoin 3 legs to their respective traces :(.

 

I'm "fairly" confident the chip is hooked up properly now, Ive tested continuity on all legs from both parts and solder sides. (Although I think one or two legs didn't seem to have any traces at all, I figure those are unused?).

 

If I don't get any more leads, I'll cut it out as you suggest, clean and inspect the board and drop in those machine pins.

 

Cheers.

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Was it working fine previously? Are you 100% the pinout of the jamma adapter is correct?

 

I ask as I made an adapter for a Puzzle Bobble bootleg and the RGB lines differed to the pinout available online. I had to adjust the adapter to suit.

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Thanks for all the awesome tips holy-snes, I have spent quite a lot of time tracing each of the 8 legs from the replaced 174 chip, I had damaged the board and needed to use little jump wires on solder side to rejoin 3 legs to their respective traces :(.

 

I'm "fairly" confident the chip is hooked up properly now, Ive tested continuity on all legs from both parts and solder sides. (Although I think one or two legs didn't seem to have any traces at all, I figure those are unused?).

 

If I don't get any more leads, I'll cut it out as you suggest, clean and inspect the board and drop in those machine pins.

 

Cheers.

 

I checked mine and all pins are used.

I'm assuming you're only checking the underside of the board. Traces run on the top side also.

I'll remove that IC from mine and let you know what goes where.

 

- - - Updated - - -

 

Here you go...

 

IC154 TOPSIDE

 

Pin 1 - IC153 Pin 1 - IC77 Pin 6

Pin 2 - NA

Pin 3 - NA

Pin 4 - NA

Pin 5 - Resistor pack (pin 6) between IC154 and IC155

Pin 6 - NA

Pin 7 - Resistor pack (pin 8) between IC154 and IC155

Pin 8 - Ground

 

Pin 9 - IC155 Pin 11 - IC153 Pin 9

Pin 10 - Resistor pack (pin 7) between IC154 and IC155

Pin 11 - NA

Pin 12 - NA

Pin 13 - NA

Pin 14 - NA

Pin 15 - Resistor pack (pin 4) between IC153 and IC154

Pin 16 - NA (5V from underside)

 

IC154 UNDERSIDE

 

Pin 1 - NA

Pin 2 - Left side of resistor right of IC134

Pin 3 - IC134 Pin 12

Pin 4 - IC134 Pin 11

Pin 5 - NA

Pin 6 - IC134 Pin 10

Pin 7 - NA

Pin 8 - NA (Ground from Topside)

 

Pin 9 - NA

Pin 10 - NA

Pin 11 - IC134 Pin 9

Pin 12 - Right side of resistor right of IC133

Pin 13 - IC133 Pin 12

Pin 14 - IC133 Pin 11

Pin 15 - NA

Pin 16 - 5V

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Thanks SNES that's an amazing piece of detail, I really appreciate it and I'll test each and every pin.

 

Only problem is my board has no ICxxx references, so I'm a bit lost, but I reakon I'll be able to figure it out based on locating the IC134 from bottom side etc.

 

I'll post back once I get a chance to test all 32 pins!

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Ok you were right! I hadn't properly tested the parts/top side pins...

 

I found two that weren't connected, they were:

 

Pin 5 - Resistor pack (pin 6) between IC154 and IC155

Pin 7 - Resistor pack (pin 8) between IC154 and IC155

 

So I somehow managed to get those two hooked up with a few random blobs of solder...

 

Walked the board back to the cab with high confidence that this would solve it... But nooooo, still doing the same junk!

 

One pin I was unsure how to test was:

 

Pin 1 - IC153 Pin 1 - IC77 Pin 6

 

Trace to IC153 Pin 1 was obvious (neighbour chip) and tested OK, but I have no idea what or where IC77 is, so this one trace remains untested and is my only glimmer of hope.....

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I think pin 1 went to a solder point to the right of it. But if it's going to the neighbouring IC then that point was in-between them so it should be connected.

 

EDIT: I forgot I took a pic...

 

[ATTACH=CONFIG]145820[/ATTACH]

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Ok so I've triple checked every pin (16 top and 16 underneath) and all align with yours.

 

I've then tried a piggy back with another 174 incase I had fried the first one, doesn't make any difference, if I wiggle the piggy back chip it doesn't impact the double up GFX at all, just slightly dims a few colours.

 

So now I'm lost for leads again, could this be a RAM issue? It's especially curious how the double up doesn't show on the credit screen until after it seems to have "loaded" of sorts. That's about the only observation I've got.

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I just booted my board without this IC and it doesn't replicate your issue, only affects the red.

As your board was working prior, I'd suggest looking over the entirety of the board to see if you've touched anything. Perhaps dropped a solder blob somewhere? Bent a pin underneath to make contact with another? If it had issues previously I'd say a logic fault, but being working prior to your repair, it would be a huge coincidence for a fault to arise at that exact moment. Unless you've shorted something, but that could only happen if you're fiddling around with the power on.

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