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

[ChrisBEANS]

I'm really sad to be back here guys, but... well, I'm back here guys

So I've had the opportunity to give the U4 some attention, and the 'short' that was happening when the cab arrived, which then without rhyme or reason went away, is back...


The reason I was able to film it is because it had cracked a few seconds before hand so I suspected it was coming.

As you can see, no interraction with the cab at all, it just goes. You can also hear, it's the screen that goes but the MVS carries on as normal in the background. The flourescent bulb stays lit too.


This is the same fault as when it arrived, but as you can see in the first video on the very first post, it previously seemed to be affected by the CP.

The cab was then moved, and the 'short' (I'll call it that until we know what it really is?!) just went away. I didn't put hours into gaming on the machine, but long enough to be happy that whatever was wrong had righted itself.

Since then the machine has been moved upstairs and the 'short' has returned.



Things I've done since receiving the cab (so they can probably be ruled out as a cause):-

Completely rewired the CP. New wires, new sticks and buttons, everything thoroughly insulated.

Removed the internal stepdown transformer (that was causing screen wobble).

The cab is now powered by a large and very stable Air Link transformer.

Found the strange bundle of wires that were taped together (they were all to do with the coin mech and coin counter) and removed the whole lot (The ground and coin #1 buttons that were spliced in to the bundle are well taped up awaiting a 'coin' button in the future).

Removed the coin mech and anything that was attached to it.

Visually inspected the wiring in the cab (I've zero idea what I'm really looking at, but everything seemed well insulated and there were no random loose ground wires that I could find).

I think it's unlikely to be anything to do with the PSU as everything else stays running smoothly...



Any help, advice or insight would be very gratefully received. This genuinely is my grail cab, and I'm doing my best to get it up to top notch condition, but I've got no clue when it comes to monitors at all.

[Astrix]

I'm not terribly well versed in monitor issues either, and maybe one of the monitor gurus will have a better insight, but it kinda looks like it's some kind of protection mode? When you say it cracked before hand do you mean the image or audibly cracked?

[ChrisBEANS]

I'm not terribly well versed in monitor issues either, and maybe one of the monitor gurus will have a better insight, but it kinda looks like it's some kind of protection mode? When you say it cracked before hand do you mean the image or audibly cracked?

Any input is appreciated!!

So, in the above video you see the screen go dark, a bright line, and you hear an aubible ‘crack’.

It does exactly this once or twice, but stays on. Then, for whatever reason, it does the same again but the screen stays off...

I’ve had the machine on next to me for the last hour or so, I’ve had no interaction with it at all, and it’s running fine.

It’s such a strange issue! There genuinely doesn’t seem to be any clear catalyst?!

[Astrix]

Yea I dunno doesn't really feel like a short to me especially since you aren't interacting with or moving the cab in any way. Possibly something on the chassis causing it to shut down. Hopefully Grant might know.

There's nothing worse than monitor issues, beautiful picture quality but huge pains in the butt when they don't work right...

[thomj]

I'd say just send the chassis to Grant. You know what to do and where he is now.

[ChrisBEANS]

So it’s been running for probably two hours now with zero issue.

If I didn’t have video I’d feel like a fraud!!

I might play on it a bit, see if it crashes??

My main concern is that as I’ve no idea what’s going on, that one time it’ll die and it’ll never come back on??

[ChrisBEANS]

I'd say just send the chassis to Grant. You know what to do and where he is now.

I hear you, and I did think about that earlier...

That’s why I left it running this evening. I figured if it’s just a matter of time until it happens then Grant can recreate the problem and is bound to be able to fix it... but I’m really not 100% certain the problem is monitor/chassis related and not caused elsewhere...

[sven666]

Proboably a cracked solder somewhere on the chassis, possibly where the power connector goes going by the behaviour, try just reflowing that before you ship it to grant

[ChrisBEANS]

Proboably a cracked solder somewhere on the chassis, possibly where the power connector goes going by the behaviour, try just reflowing that before you ship it to grant

You reckon?? That’d be amazing!!

I’d never dream of trying myself, but I’m lucky enough that Grant lives 30 minutes away, so it’s no drama at all to drop it to him


P.S. I haven’t forgotten about that U4... just not sure I’m ready yet

You seen your countryman selling the MV25UP? It’s a beauty!

[ChrisBEANS]

I’ve posted this elsewhere too, but for anyone paying attention to this thread...

[media] [/media]

It lives!!! I left it on for about 8-10 hours on Saturday, and even gave the cabinet a little nudge (really little) to make sure it was stable and didn’t short out again... All good!!

The chassis itself was physically cracked. Grant tells me he repaired four tracks and replaced a couple of prior repairs.

The blokes a bloody wizard, and as always great price and double quick.

Worth saying, the damage appears to have occurred in shipping. Not Sven’s fault at all, as the machine spent a couple of weeks on a pallet getting here.

[wonderbanana]

Bit of a bump I’ve been reading through this rather awesome thread as I have the same cab and although its far from my first, it is my first in best part of a decade so I can’t remember naff all

My main question is based on the the internal step down. Mine has this and I can see Chris experienced screen wobble because of it.

Ive not noticed this on mine but I did wonder if these transformers can cause any long term damage or if any effects like Chris experienced are essentially environmental? I’m assuming not as this thing would have been in for years but I thought I’d best check…

[wonderbanana]

Anyone?