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

[thegreathopper]

Excellent news!

[ChrisBEANS]

The new cab turned up today too! Exciting times!!

[yosai]

The new cab turned up today too! Exciting times!!

New thread incoming....

[grantspain]

yeah pretty epic post for a loose wire and a stepdown a bit close to a deflection coil

[Wurstkopp]

Sorry.

[ChrisBEANS]

Ha, yeah I guess it did spiral! I’m just trying to make sure I don’t knacker anything

While we’re in a screen sub forum... any ideas what trimming tool to use for the width adjustment?

I’ve bought two sets (can link them if needs be) and even the smallest is too big for the hole in the chassis...

Transformer arrives soon, so that’ll be the wobble sorted hopefully too.

I used the screen calibration guide that was linked earlier and it looks great now too.

Happy days!! Thanks all for the help!

[grantspain]

https://www.arcadepartsandrepair.com/st ... ment-tool/

this is the best one i use, its very solid and can even shift seized k7000 coils

[ChrisBEANS]

Not much of an update lately, waiting on bits to arrive. Unfortunately can't get the width trimming tool as the only place that I can find the specific one I need won't ship to the UK.

In the mean time there's still the screen wobble to sort.

This is where I need to be double sure I know what I'm doing so please excuse me if I'm asking really dumb stuff, I'm largely looking for confirmation...

I've got a step down transformer:-



and I've looked at the PSU in the cab.

As I understand it, what I need is to wire a fused three pin japanese plug to use transformer end, and simply attatch the neutral wire to the bottom pin on connector, live to the one up, ground to the one up again, right?





Finally, if that's correct, any ideas where to get a Japanese plug?? I can find adapters, I can find Euro and US plugs, but I don't seem to be able to find a straight Japanese plug I can wire up.

Cheers again all...

The wobble, while really apparent in person doesn't show up very well on camera, but I'll try to post a before and after video.

[yosai]

any ideas where to get a Japanese plug??

For the plug you could use an IEC

https://uk.rs-online.com/web/p/power-ca ... s/9092180/

Get one of these and cut off the IEC end.

[ChrisBEANS]

Of course!! Simple as that!! Cheers dude, I'll get on it

[nem]

Wiring up the power lead straight to the PSU is a bad idea. If you're going to do that how are you going to switch off the cab? In addition to the power switch, you're also likely bypassing a fuse, a noise filter, and a junction point for AC (unless the PSU is it, I don't know). AC powers not only the PSU, but also the monitor and the marquee light.

Without seeing how it is wired, my best guess advice would be to remove the transformer. Connect the input and output wires together either by soldering them and putting heatshrink tube over the joint or using close end connectors. Then replace the power lead with one that has a Japanese plug at the end.

Also, UK standards don't conform to the rest of the world. No other country (that I know of) puts fuses at the plug. There is no such thing as a fused Japanese plug.

[cools]

What nem said. We need to see more of where the stepdown is wired inside to be able to advise.

(UK mains standards ftw, btw )

[ChrisBEANS]

Noted... I’ll probably not get to doing this double soon, but I’ll try to post as many pics of how it’s currently wired before I do...

[ChrisBEANS]

As standard, I'm now double confused...

Of the three wires coming in from the plug (Black, White, Red/Pink)...

The red/pink is clearly the ground. As it comes in, it's then joined, under tape, to a green earth wire that is connected to the bottom of the case. Simple so far...

The black wire, which appears to be the neutral goes into the back of this thing below (whatever it may be?!), comes straight back out, and goes to the neutral input on the back of the stepdown. Again, straightforward enough.



This is where I get lost...

The white (live) wire comes in, also goes into the back of the same black thing as pictured above (Green arrow), comes straight out, and is then joined to the BLACK wire of a two core cable that snakes off into the machine (White arrow), which appears to serve the monitor at a guess??
However the WHITE wire from the SAME two core cable, at the same end where the UK 240v white wire is spliced with the black wire, goes to the live input terminal for the stepdown (red arrow).



Does this mean that the CRT and chassis are 240v and the PSU is obviously 110v as per the output on the step down?

[nem]

this thing below (whatever it may be?!)

It's a socket. If you have multiple cabs you can just daisy chain them and you don't have to have a power strip. It's really convenient.

a two core cable that snakes off into the machine (White arrow), which appears to serve the monitor at a guess??

Nope. The monitor will run on 100VAC.

Maybe it's for the power switch? There is one, right? If it's indeed for the power switch, it means the switch kills only one side of AC, which is poor practice, but I've seen it done before. Personally, I wouldn't use that switch and I would always cut power by pulling the plug on it.

Anyway, my best advice would still be to just connect the input and output wires for the transformer together. As long as you don't mix Earth ground with either Live or Neutral, you'll be fine. Black to black, white to white. Put green under a cabinet screw or something, don't leave it untethered.

[ChrisBEANS]

Really appreciate all the help!

I’m certain it’s annoying, but I promise not to ask the same question twice!!

I’ll get the input/outputs spliced together, bung on a Japanese plug, and if that fixes the wobble I’ll be extremely happy!!

Thanks again.

[ChrisBEANS]

Finally, by way of some closure, I installed a different four slot board.

No issues at all, happy days.

Then I got all brave... soldered together input/output wires, bypassing the internal step down. (Good god is that thing heavy!!)
Covered it all in heat shrink too, all as per Nem’s advice.

Wired a Japanese plug to the other end and slung it into an external transformer.

The result? The picture is absolutely rock solid stable. Not a wobble in sight.

To say I’m dead pleased would be a massive understatement!!

Thanks all, massively, for all the pointers and advice.

[nem]

Nice! Well done!

Pretty involved for your first cab!

[thegreathopper]

Well done

[markedkiller78]

Well done it’s pretty intimidating to start with, but you now know how the cab is wired and how it all works.

It’s time to play some games and enjoy it