Q&A Thread

[CraftyMech]

Who's yer daddy?

Thanks for the link! That was a rhetorical question right?

I received the 1943 chips today, and had a chance to solder one in tonight. Unfortunately, the new chip behaves the same as the previous one did with pins 5&6 shorted. So although I don't have to short pins 5&6 on the new chip anymore to fix the sprite palette issues, there was no additional improvement to the pulsating jail bar pattern on the game sprites (except for bullets and the player sprites which are fine).

So out of luck in that location I followed the action downstream and decided to investigate a blue Krylon wire that connected two pins on two different D-type dual flip flop ICs (74s). Without the connection, the clock pin of the 2A flip flop is floating, and the result is no graphic sprites of any kind (just backgrounds and text). I was scratching my head until I googled 1943 pcbs and discovered that all the images I could find had this same blue wire. So it wasn't evidence of an early repair as I had thought, but perhaps patch work done at the factory?

Last thing I tried tonight was piggybacking a pin compatible 74 onto the 4-5 Flip Flops in the same area on the board. No change however with the sprite jail bars.

So at this point there is the big graphics chip that might be the culprit after all, unless I can come up with something else. 

[channelmaniac]

Yeah, that big one is a pesky problem

If the TTL/LS chips are shorted, piggybacking won't show that. You'll have to replace them to find out if they were the problem.

Raymond

[CraftyMech]

In the process, I have learned a couple interesting things about the 1943 board set. I found a picture of a B board with three small daughter boards instead of the three custom chips you sent me. The boards had Capcom labeling and model numbers, so maybe the early 1943 releases didn't have the custom chips yet. I also found that connecting the 2A clock pin to a pin 32 on that big graphics chip would pause the game. Could be a handy feature since 1943 has so many stages!

[TPMARTIN]

My buddy and I purchased a set of Indy 500 racing games and it worked perfect at the guys house.

BUT...

When we got the machines back to his house the Fiber Optic system that is hooked to the coinbox is missing, we called the guy we bought it from and he said he doesn't have it and we didn't leave it behind ( DON'T ASK...we are still looking for it ).

Do you know if that piece is replacable and if so where? or if there is a way to bypass that coinbox and plug the machines directly into each other?

Thanks

Tim

[channelmaniac]

The fiber optic cables are simple Toslink cables and you can get them at Radio Shack, Fry's, and other places.

[TPMARTIN]

Do you know if I can bypass the coin box inputs and plug directly to and from machine?

[channelmaniac]

You should be able to. I think those are just cables from the board to a jack to make it easier to get to.

[hairy otter]

Still confused. Sorry, but every time I try to look for the faulty chip an other one seems to be bad.
If I flip dip8 to pause and start pulling up input signals a different chip alters the appearance of the line. The chip that seemed faulty in previous tests only add another line. Also if I ad a line by puling up an input those lines look different than the one whose always there?
I try to test continuity of all tracks but it takes quite some time. And I think there isn't a problem as with all 32 27F251's lines change or appear on the screen.
The only thing I suspect is the IC in the SFIX IC-foot.(it says 381000-20, 7C6 BK, 9035 Z01) The SC1 and SC feet are empty? Then the tracks go to the SNK PRO CT0 chip.

I found the time to check all connections from the 27ls251, via the boardconnectors, all the way down to the grafix chip on the bottom board. If you like I can post my findings in a table for others to use?
But all tracks are continuous.
While I was looking at the bottom with my 20x watch repair eyeglasses to find some damage to other tracks, I spotted 2 small holes in the backup battery? As the problem started after putting that battery in, I should have seen this earlyer! But before I soldered in the battery I checked the space and it was fine if I trimmed the ic-legs. But the battery wasn't fully flat down after soldering as I see now. So I pushed the battery down and checked again for space. Now its OK.
Put the 2 boards together again and tested. Works like a charm.
Seems to be my logic probe isn't up for the job, as I didn't find the error while checking the shorted pins.
After this I found on http://www.arcadecomponents.com that the the type of battery I used doesn't fit in a 6-slot board and I found out the hard way.

[channelmaniac]

PM me the info on the connections and I'll post it in my SNK thread, or you can post in the NLG Users' Repair Logs section.

Congrats on getting it fixed!

Yes, on the 4 slot boards there are no chips above the battery on the top board. With the 6 slot board there is a chip above it which will poke through the insulation on the battery and short it out.

It's best to use an off-board NiCd or NiMH battery on those... or a CR2032 lithium coin cell conversion. Just make sure you neuter the charging circuit before using the coin cell or it will leak or rupture.

[CraftyMech]

Update on my ongoing 1943 saga...

I picked up another "not working" 1943 boardset last week. This one had a missing 8751 PROM (security chip) on the A board, so I was hoping the B board was good to replace the B board in my original set. So I pulled the 8751 from my first boardset and used the chip to replace the missing PROM, and fired up the new boardset to test. And surprise, the new boardset fired up and had the same graphic glitches that my original 1943 had. I also have a bootleg 1943 set, which doesn't use the 8751 at all, so I hooked the bootleg A board up to the B boards from my other sets, and confirmed that both B boards worked just fine! So it seems the issue with my original board is a bad 8751, or both A boards just happen to have the exact same graphic glitches.

Being a security chip, I'm guessing the 8751 has not been dumped, but I need to check the MAME romset. ** Checked the dump list, and as of Feb, the 8751 for 1943 has not been "decapped" and dumped. So now I'm in the hunt for two working 8751 chips, to get both board sets working.

Since the bootleg A/ Capcom B gave me a working game, I tried an experiment to fix the English translation on the bootleg by swapping the BM04 EPROM for a Capcom BM04. Rather then fix the translations though, the PROM swap switched the game to Japanese! So I guess the bootleg is really a Japanese 1943 with English "dubbing" from the BM04 PROM. So I have now a working Japanese version of 1943, but the only catch is the sound from the bootleg A board is rough, like it isn't being mixed properly (sound effects are loud and crackle, music sounds fine but is low in volume).

The journey continues...

[channelmaniac]

Crazy!

Not sure if I have any of the 8751 chips from the 1943 boards. I think all the boards in my big pile o'scrap are other Capcom boards and not 1943.

On the sound issue, the first thing to do would be to recap the audio section.

[hairy otter]

Graphic problem NEO MVH SLOT4FS

I have a 4 slot neo geo, one of the "new" 4FS type.

In a video on my youtube you can see what I mean. I can't explain what is on the screen. There is no audio on the video, but this is because I turned the volume down.

<a href="http://www.youtube.com/v/wacvY-23Q2A&rel=0" target="_blank">http://www.youtube.com/v/wacvY-23Q2A&rel=0</a>

Where do I start to fix this. I tried finding broken tracks but can't find any. The slots are cleaned well and all slots give the same problem. The cart is OK, it runs well on my other 4 and 6 slots. But the other 4slot is of an older type so I cant switch top and bottom boards.

Anny suggestions?

[channelmaniac]

Start by cleaning the slots, looking for gouged traces on the top of the top board and bottom of the bottom board. Look for liquid spills or rodent damage around the chips on the top board which will result in trace damage. Next, check the address and data lines going to the cartridge slot for missing signals.

[hairy otter]

Thanks channelmaniac, I found 2 broken traces really close to the IC pins. The pins had turned green by some mouse pee. The board was full of pee and droppings when I bought it.

Just another question. Along with the board i got a ctrg of Top Hunter. It also needed allot of cleaning. I took it appart, cleaned the contacts with an eraser as you told me before. After this the game didn't play well, so I re-soldered the whole board. Now it plays but there is no sound. Also, if i put it in my multy-boards, ones it comes by, all games lose sound. I tried it on my 2 four slotters and on my 6 six slotters all with the same result. Is there any way to fix this?

Regards.

[channelmaniac]

Check the traces going to the M1 ROM, especially around the mounting holes in the board. If they are all good, replace the ROM.

[CraftyMech]

Update of my ongoing 1943 repair saga...

Finally got around to recapping the sound section of the bootleg A board I am using, and now the music volume is back to the right level. The sound effects still sound a little distorted and loud, but the sound quality in general is much improved. Not knowing if the bootleg sound was just poorly mixed to begin with, I'm at a point where I think I can live with the boardset at 90% versus putting anymore time into it. If I come across a working legit A board for 1943 I'll swap it out in a heartbeat, but otherwise I think this repair saga has come to an end!

[channelmaniac]

If you have an oscilloscope you can check the op amps to see if one is bad.

[CraftyMech]

I do have a scope (a basic BK 2120) so I'll look for op amp chips in that section and check them out.

I recently splurged and picked up a Hako 808 for desoldering. What a difference, night and day versus a solder pump! I followed your advice on soldering smd chips as well, but instead of fixing bridged pins with solder braid used a quick shot with the Hako. The chip barely felt hot to the touch when I was done. I never thought I'd be able to solder up a 28pin TSSOP at home, but it worked like a charm!

[channelmaniac]

I wipe the tip of the iron clean, put a little rosin flux on the pins, and use the iron to draw off the solder bridges. Works like a champ, especially on the super tiny pins that you can't get close enough to with the desoldering iron tip.

RJ

[hairy otter]

Check the traces going to the M1 ROM, especially around the mounting holes in the board. If they are all good, replace the ROM.

All traces  of the M1 ROM test OK. So i think the ROM is bad. Do you sell these in your on line shop? And do you ship to Europe?

[channelmaniac]

Yes, but shipping is very expensive now to Europe.

Which ROM is that - a 27C010 or 27C301?

[hairy otter]

How do I know what ROM it is?

Here is a picture (its not mine but it's just the same, I used it to compare jumpers)
http://mvs.gotwalls.com/images/e/e3/Top_hunter_set1_b2_front.jpg

What would be the shipping cost?

[channelmaniac]

Not 100% sure... but since it has 32 pins available for it, but is only a 28 pin chip, and is 1 1Mb ROM, I'd say it's a 23C1000 OTP ROM which you'd need to replace with a 27C301.

Raymond

[hairy otter]

I checked the Rom on the far left of the board, the one with M1 printed below. That's a 32 pin chip, the one with S1 underneath is one with 28 pins. Is this the one I need to replace/check?

[channelmaniac]

Check the pinouts of the ROM and try to determine which is A16 and which is /OE to determine if it's a 27C301 or 27C010. Probably will be a 27C301.