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

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phillv85
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by phillv85 »

cools wrote: April 6th, 2021, 7:19 pm
ChrisBEANS wrote: April 6th, 2021, 6:05 pm
cools wrote: April 6th, 2021, 5:55 pm FWIW I've had issues with stuff I know I've thoroughly tested before shipping, and the buyer reporting it back to me, sending it back, and lo and behold the issue they've reported (that I tested for) is legit. The only explanation is the shipping, as by cleaning/resoldering something has fixed it.

I'm wondering whether your stepdown is grounded properly?
I can take pics of the step down if you think it’s worth doing??
Nah, unless you have a multimeter to check it?

I'm just suspicious whether you're grounding the cab when touching something...
That’s also my suspicion.
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nem
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by nem »

Wait a minute, didn't this have an internal step down though? It had been converted to '220V'.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

It has an internal step down...

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

Post by nem »

It's set to 2:1. Irrevelant for now, but something you will want to change down the line. These are meant to run on 100VAC.

What kind of power lead do you have on it?
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by PrincessPrinPrin »

nem wrote: April 6th, 2021, 6:21 pm
PrincessPrinPrin wrote: April 6th, 2021, 6:14 pm
Wurstkopp wrote: April 6th, 2021, 5:53 pmseems to be a Nanao MS8-25.
26.
It's a 25" cab though? What function does SW331 have on the neck board?
I don't know if the monitor is a 25" or 26". All I know is that the MS8-26 has a transistor based vertical deflection and as such it requires a high impedance vertical yoke. Do you know of any 25" monitor with this feature? I don't. And the yoke doesn't seem to have been replaced as the bonding compound on the screw is intact.
Im running games with a vga to tv converter on my Shangai Novel, with composite and it looks amazing, Im not interested in RGB or Scart.

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

Post by Wurstkopp »

A picture of the back of the tube would be interesting.

Btw: Great to hear that everything seems fine now. It's a great pain for both the buyer and the seller when something happens during transport. So glwtc(ab), it's a real beaut. :awe:
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by geotrig »

phillv85 wrote: April 6th, 2021, 7:31 pm
cools wrote: April 6th, 2021, 7:19 pm
ChrisBEANS wrote: April 6th, 2021, 6:05 pm

I can take pics of the step down if you think it’s worth doing??
Nah, unless you have a multimeter to check it?

I'm just suspicious whether you're grounding the cab when touching something...
That’s also my suspicion.
Was thinking the same sounds like a ground fault somewhere, I'm almost certain we've seen this somewhere else before here.
Chris do you know if your carts are good? Give the contacts a good clean either way also what's you voltages running at even barely moved cabs voltages go out of sync... Either way we've all been there... It s the fun part of the hobby :lol: :problem:
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by sven666 »

The white two prong connector from the front is degauss button, its not needed as the nanao autodegausess on startup.

I can see the coincontroller has fallen off the wall, it should attach beside the coinchute on thw wall with sticky tape, make sure its not shorting something out.
Pull on the totes on both the transformer and psu so that nothing has a loose connection.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

Deffo not the cart, I’ve got an OMVS and the carts are all in good order (and I cleaned them all too ;) ).

I’ll have a look at the coin controller now and another look at the PSU/step down now...
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by nem »

Was a UK plug installed on it?

That's what I would look at.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

I changed the euro plug to a UK...
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

Before...

Image

Step down, showing black on 0, white on 220v and what you can't see in this image is that the red wire is the ground...

Image

After...

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

Post by nem »

That looks OK (provided red is connected to the shell of the cab).

Is DC ground separated from Earth? I know these are sometimes connected together, but personally I never do it. Check the PSU for that.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by sven666 »

Try unplugging the 4slot and turn the cab on, still the same problem?

I can really only see three possible things this could be.
A wire is pinched somewhere causing a short.
The psu/transformer has developed a fault.
The chassis has developed a fault.

I think the chassis being broken is the most unlikly, it was revised by either grantspain or my current chassi guy, cant remember who did it as ive had way to many fixed..

Transformer and psu are easily measured with a multimeter, start with the transformer and have a friend jiggle the sticks to see what it does.

Pinched/loose wire, start following wires, start with the panel and go down the cab, this is a metal cab so its not entierly unlikely that there could be a scratch in the isolation somewhere.

As for the game being garbled, thats just multislot life im afraid, try another slot and reseating it multiple times, multislots are extremely tempramental :( once you get it going it will usually stay good untill you change the lineup tho..
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by sven666 »

I think a short somewhere along the controlpanel is most likely, you can clearly see the picture jump when you touch the joysticks.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by grantspain »

have you worked out if its the entire cab supply shutting off or just game board or just monitor- easy way to prove power on without game board, turn up brightness so you can a raster and then do the things that caused it to shut down
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by SuperPang »

The credit LED appears to stay on in the video.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

Sorry, not had any opportunity to look at it properly today.

Just spent ten minutes with it and it’s very promising news, but I’m more baffled than before!!

My plan was to just turn it on for ten minutes and see if it simply stayed on.

Childish impatience got the better of me and I ended up moving the sticks and pressing the buttons too...

No crackling, screen stayed on. Great news!!

My only issue with that, is that I’ve done nothing, moved nothing, unplugged nothing. If the short or the grounding has spontaneously gone away, it can spontaneously come back, right??
I’d have much preferred to actually find something...

Then on to the four slot... more baffling still...

Yesterday I’d used MS2, and I tried it in slots 1 and 2, reseating it several times. Every time I got the screwed up sound.

Today, I put MS4 and MS5 in slots 3 and 4 and at a superficial few seconds of playing each they both seemed to work fine.

So, as slot 4 is apparently no issue, I put MS2 in it. Same sound issue.

Seems by elimination that the problem is MS2, right? But it really isn’t. I’ve got an OMVS (consolized MVS) and not only did I properly clean the cart when I got it, but I’ve been playing a ton of MS2 on it with zero issue, and after the problems yesterday I tried it on the OMVS again, and again no issue...??

I’m double baffled.

Just a brief update, I might not actually get to look at it properly until tonight, but I appreciate everyone taking an interest and trying to help and I didn’t want to leave you hanging or to appear that I’d lost interest.
Last edited by ChrisBEANS on April 7th, 2021, 12:24 pm, edited 1 time in total.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

grantspain wrote: April 7th, 2021, 10:24 am have you worked out if its the entire cab supply shutting off or just game board or just monitor- easy way to prove power on without game board, turn up brightness so you can a raster and then do the things that caused it to shut down
Sorry, yes, was just the monitor. Credit light stayed on when it tripped out as Pang observed...
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by thomj »

Have you measured the voltage on the 4 slot? It could be 2 is pickier about the 5V than the others.
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