SNK U4 - Screen crackles and dies REDUX!!!!

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ChrisBEANS
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

As above, I've now adjusted it to an exact 5.0v on all four pins. (still only one of the 12v pins has any reading though?).

Same sound issues. Video below. It's 2 minutes long, which is obviously excessive, but I figured anyone who's actually taking an interest could watch until they're satuisfied rather than me cutting it off at an arbitrary point...

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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

geotrig wrote: April 12th, 2021, 9:28 pm Is your jamma edge "keyed" ?
It's not, no... but I found a photo I'd taken that shows it's 'print side up'...
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by Buddyc »

29F14ECF-22A2-4F59-9579-996F3DC0C344.jpeg
“Key” is the space between 12v pin and coin counter 2. (H and 7)
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by geotrig »

Just wondering what bios the 4 slots running?
The fact 5 is running in all slots ok and ms 1/2 isnt is odd considering you know both are good. Have you tried seating one of them slightly different in the slots to see if a better contact might be needed, hard fully pushed in isn't always needed from experience
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<trk>:I remember catching a big fat one and my friend said "throw it back in, that one already tastes like wood"
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by geotrig »

I'd also suggest once the jamma metered connector arrives keying that to save iheartache in the future
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<trk>:I remember catching a big fat one and my friend said "throw it back in, that one already tastes like wood"
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

Cheers Geo...

So no idea what BIOS is currently installed, but I do have a UniBIOS that I obviously intend to install eventually but I can do that sooner if you think it might help.

I’ve just put MotW in it, and that seems to run pretty much correctly.
The music is actually slightly off, but you’d really only know if you you’re really familiar with that game. Hard to explain. It’s all in time, and 99% there, but it’s like there are ‘layers’ of music missing.

It’s a strange one to be sure!!
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

So MS runs with the sound issues and was in slot 1, Neo Turf Masters had sound issues in slot 2, and MotW was 99% in slot 3.

So, I swapped MotW over. MotW in 1, MS in 3. Moved Turf Masters to 4.

Exact same sound issues.

All carts work perfectly on the consolized MVS, and the PSU has now been adjusted to an exact 5.0v on the four 5v pins...

That’s where I leave it tonight.

Again, I genuinely appreciate everyone’s help, advice and interest 8-)
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by geotrig »

Hmm odd , if all slots and contacts on mb and cart are clean it could be the Yamaha chip failing ym26*** c(an't remember the name) or z80 , the Ym is soldered and z80 is socketed,
You could switch the z80 from your colsised MVS if that is socketed or to test that ,Did you say at some point you have another 4 slot on the way? You could pull it from that if it tests food to see if the colsolised one is soldered.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

Actually, as we’re still in the monitor section, this is a general question but might be best answered by @grantspain maybe?

The screen as is seems about right at first, but after sitting in front of it for a few minutes you notice some oddness.

So the bright areas might be just a little too bright, but the dark areas are equally too dark. You lose some detail in the dark areas. Detail I only really know is there from playing on the consolized MVS.

A specific example, if you know the game, is on Mark of the Wolves. On the character select screen, Butt’s profile pic. The shaded areas of his face and his hairline all fade into one.

The picture is also slightly fuzzy. As though it’s very slightly out of focus, if that makes sense? Lastly, bright areas actually expand! So if there’s a particularly bright area, for example the ‘continue’ countdown on MotW, the white numbers cause the rest of the screen to very slightly warp, as if the brighter areas are expanding.

Is this something I can deal with by adjusting things on the chassis, or is this the nature of CRTs??


To be double and triple clear, these are NOT complaints or anything other than small things I’ve noticed, I’m simply trying to understand things better as I’m now involved in this awesome hobby...
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by geotrig »

https://wiki.arcadeotaku.com/w/How_to_C ... Brightness
Test pattern is different but have a read of this to set up your colours, it could be your brightness is too high with some colours set low
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

geotrig wrote: April 12th, 2021, 11:28 pm Hmm odd , if all slots and contacts on mb and cart are clean it could be the Yamaha chip failing ym26*** c(an't remember the name) or z80 , the Ym is soldered and z80 is socketed,
You could switch the z80 from your colsised MVS if that is socketed or to test that ,Did you say at some point you have another 4 slot on the way? You could pull it from that if it tests food to see if the colsolised one is soldered.
Yes, got a four slot and a six slot coming with another cab I’ve bought that I’m woefully under qualified to look after :lol:

Perhaps I’ll wait for that?

Oh... as I type... I’ve been sitting in front of it and I noticed it was silent. It had been making noises all the time (incorrectly for MS, and correctly for MotW), but now was silent. I started a game of MotW, and nothing.

I turned it off and on again (standard), and back to exactly as it was before. Same issues on MS and Turf Masters, no issues on MotW. Don’t know if that makes any difference to the diagnosis?

If it is the case that I simply need to get a new 4 slot, that’s not the end of the world I guess.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by sven666 »

Hey, test the speakers in the mobo test menu, it could be a speaker has broken, I sold my other two of these cabs to another collector and one of the speakers in those cabs broke during transit.

it has left/right test individually so pretty easy to check, i think i still have a spare speaker if one should be broken.

also note you cannot run a 6slot in this cab (it wont even fit), the 6slot draws alot more power and wont run on most cabs PSUs properly..
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by grantspain »

from the distant past i am sure neo 6 slot are not standard jamma- the speakers are wired differently
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

Speakers are all good. Work in hardware test, and they work on the games that work...

The six slot is for a six slot cab I’ve got coming, but it’s been described as ‘wonky’, so it’s also being supplied with a four slot that’s supposed to be in top order.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by SuperPang »

ChrisBEANS wrote: April 12th, 2021, 11:32 pm So the bright areas might be just a little too bright, but the dark areas are equally too dark. You lose some detail in the dark areas. Detail I only really know is there from playing on the consolized MVS.

A specific example, if you know the game, is on Mark of the Wolves. On the character select screen, Butt’s profile pic. The shaded areas of his face and his hairline all fade into one.

The picture is also slightly fuzzy. As though it’s very slightly out of focus, if that makes sense? Lastly, bright areas actually expand! So if there’s a particularly bright area, for example the ‘continue’ countdown on MotW, the white numbers cause the rest of the screen to very slightly warp, as if the brighter areas are expanding.

Is this something I can deal with by adjusting things on the chassis, or is this the nature of CRTs??
Some further tweaking should improve any contrast and colour balance issues (use the colour gradient screen). Do this after the monitor has warmed up.

The "expanding" you describe is pretty normal, in moderation.

In this hobby you will come to realise that there is no such thing as a perfect monitor and sometimes you have to learn to quit while you're ahead. I''m sure you'll spot minor niggles with your other cabs as well. The convergence is bound to be off a bit at the corners on the Blast City for example.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

SuperPang wrote: April 13th, 2021, 1:30 pm
ChrisBEANS wrote: April 12th, 2021, 11:32 pm So the bright areas might be just a little too bright, but the dark areas are equally too dark. You lose some detail in the dark areas. Detail I only really know is there from playing on the consolized MVS.

A specific example, if you know the game, is on Mark of the Wolves. On the character select screen, Butt’s profile pic. The shaded areas of his face and his hairline all fade into one.

The picture is also slightly fuzzy. As though it’s very slightly out of focus, if that makes sense? Lastly, bright areas actually expand! So if there’s a particularly bright area, for example the ‘continue’ countdown on MotW, the white numbers cause the rest of the screen to very slightly warp, as if the brighter areas are expanding.

Is this something I can deal with by adjusting things on the chassis, or is this the nature of CRTs??
Some further tweaking should improve any contrast and colour balance issues (use the colour gradient screen). Do this after the monitor has warmed up.

The "expanding" you describe is pretty normal, in moderation.

In this hobby you will come to realise that there is no such thing as a perfect monitor and sometimes you have to learn to quit while you're ahead. I''m sure you'll spot minor niggles with your other cabs as well. The convergence is bound to be off a bit at the corners on the Blast City for example.
Cheers. As I say, as is is perfectly fine, it’s just that as I’m new here I’m trying to work out what I should or shouldn’t expect...

I’ve just remembered (I know, what a ****!!) that I’ve got a one slot, and a JAMMA adapter! Now we’ve got the voltages dialled in I’ll try that tonight with MS.

Also, anyone have any thoughts on only one of the 12v pins on the harness having power?
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by thegreathopper »

12V is used for sound as far as I know, you could always put a jumper cable on your jamma edge connector to get +12V on the correct terminals.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by geotrig »

do a continuity test(when the cab is off) on the cable thats not showing 12v and see if you can trace it back to the power supply or where its terminating ,If i'm getting you right you are only getting 12v on one side of the edge connector ? that could very well be the issue as the 12v lines normally power the sound.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by geotrig »

do a continuity test(when the cab is off) on the cable thats not showing 12v and see if you can trace it back to the power supply or where its terminating ,If i'm getting you right you are only getting 12v on one side of the edge connector ? that could very well be the issue as the 12v lines normally power the sound.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

Ok... so the wire for pin F, that’s showing 12.1v traces off to a bunch of wires that have all been smooshed together and taped up with insulation tape.

Pin 6, which doesn’t have power traces directly back to the PSU, to a terminal marked 12v.

Another noob question... can I use the multi meter directly on that PSU terminal to see if it’s outputting 12v, or am I likely to break stuff?

Edit: Major correction. Pin 6 that traces back to the PSU is in fact getting 12.1v

It’s pin F, that traces back to a number of wires taped together that has no power...
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