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 »

Ah! I did it on the ‘inside’ pins of the edge while it was disconnected.

I’ll try the voltages again with it connected.

I might not get back to check on this today, but I’ll update you all as soon as I possibly can.

Thanks again all for your help :thumbup:
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by thegreathopper »

If you have been adjusting your +5 Volts dc without the 4 slot plugged in you are probably way under.

I do recall 6 slot boards have a test point on the board for measuring, it’s a long time since I had a 4 slot (Think I sold my last one to Superpang :D )
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

On the edge itself, it was 5.24 before adjusting, it’s now an even 5.

There is an area with two points on top of the PCB labelled 5v and GND... is that a better place to check then?
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by thegreathopper »

ChrisBEANS wrote: April 14th, 2021, 3:37 pm On the edge itself, it was 5.24 before adjusting, it’s now an even 5.

There is an area with two points on top of the PCB labelled 5v and GND... is that a better place to check then?
I would measure in both places and yes that’s probably why it’s marked as 5v and Gnd, it’s a test point.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

Great stuff. Frustratingly, I’m stuck at work, but I’ll go check all of this out when I can.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

Today’s round of ‘Good News / Bad News’ is as follows:-

Good
  • I’m learning
  • I now own a very nice soldering iron
Bad
  • I’ve no use for my very nice (and fairly pricey) soldering iron
  • Seems the problem is with the four slot rather than the wiring to the JAMMA(MVS) edge

So after learning that my voltage readings were pointless unless the PSU is under load I plugged it all in and did the tests again with the machine running.

My exact 5v is now a 4.94v, so I’ll up that a smidge, but seems pretty good none the less.

The 12.1 on pin 6 is now a 12.08v, and most importantly as was suggested pins 6 and F are in fact bridged on the board as when the JAMMA(MVS) edge is plugged in, pin F registers the very same 12.08v

Sound issues remain.

We know the problem isn’t the carts, as they work perfectly on the other MVS I have.

We know the problem isn’t any specific slot, as Garou seems to work without issue on any of the four slots, and MS has the same issue on any of the four slots.

I’m now a bit lost...

I guess I’ll wait for the other four slot to arrive, try that, and then find someone to repair this one??
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by nem »

ChrisBEANS wrote: April 15th, 2021, 10:14 am I’ve no use for my very nice (and fairly pricey) soldering iron
You say that now, but just you wait.

Anyway, you should wire up F back to the PSU, even though it doesn't really matter in this case. Practice on your soldering before hand. I wouldn't want to have +12V terminating to a taped bundle. That's a short waiting to happen in a cab made out of metal.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by geotrig »

ChrisBEANS wrote: April 15th, 2021, 10:14 am Today’s round of ‘Good News / Bad News’ is as follows:-

Good
  • I’m learning
  • I now own a very nice soldering iron
Bad
  • I’ve no use for my very nice (and fairly pricey) soldering iron
  • Seems the problem is with the four slot rather than the wiring to the JAMMA(MVS) edge

So after learning that my voltage readings were pointless unless the PSU is under load I plugged it all in and did the tests again with the machine running.

My exact 5v is now a 4.94v, so I’ll up that a smidge, but seems pretty good none the less.
you'll need it ,the soldering iron even if for some bit and pcs,

the 4.94v is a tad low (i've some games that wont boot at that range) try get it to around 5.02-5.05 and see if it makes any difference , dont go over 5.1
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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 thegreathopper »

Yes as Nem said, you need to get your harness wired correctly as you will end up with a huge collection of games in time, some will need all the connections.;)
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

Right, I’ll adjust the voltage, and I’ll wire pin F directly to the PSU.

Now we’re pretty happy that the fault lies with the four slot, no reason I can’t attach something else instead, right?

I’ve got a JAMMA board and a one slot MVS (and a JAMMA to MVS adaptor of course)
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

thegreathopper wrote: April 15th, 2021, 1:55 pm Yes as Nem said, you need to get your harness wired correctly as you will end up with a huge collection of games in time, some will need all the connections.;)
Nope, I’m being double strict with myself!

Only getting the games I really love, and only games I intend to 1cc.

I think I’m set for MVS stuff, I’m going the MiSTer route for CPS1 & 2, and I’ve got a sale agreed with @Monstermug for Vendetta ((best 2d beat em up ever, fact) maybe Streets of Rage 2 is better?), and that’s going to be it.

I’m aiming to be a gamer, rather than a collector.



Edit (as I don’t just want to keep spamming replies!): in relation to the screen ‘wobble’ being most likely down to the internal step down, and the suggestion I rewire a JP plug and use an external step down... wouldn’t it make more sense just to get a UK JAMMA PSU?
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by nem »

ChrisBEANS wrote: April 15th, 2021, 1:57 pmNow we’re pretty happy that the fault lies with the four slot, no reason I can’t attach something else instead, right?
Right. Plug something else in (with adapter).

ChrisBEANS wrote: April 15th, 2021, 2:01 pm and that’s going to be it.
We all say that too.

ChrisBEANS wrote: April 15th, 2021, 2:01 pmwouldn’t it make more sense just to get a UK JAMMA PSU?
No, because your monitor won't work with anything else except 100V.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by yosai »

ChrisBEANS wrote: April 15th, 2021, 2:01 pm in relation to the screen ‘wobble’ being most likely down to the internal step down, and the suggestion I rewire a JP plug and use an external step down... wouldn’t it make more sense just to get a UK JAMMA PSU?
Get yourself one of these and a JP plug

https://airlinktransformers.com/product ... -uk-ja0250

For the plug you could use an IEC

https://uk.rs-online.com/web/p/power-ca ... s/9092180/
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

I’ve got one coming already, but surely it’s just easier to get a UK PSU, isn’t it?
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by yosai »

The monitor requires 100v.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by thomj »

Make sure your adapter is the correct way round. The one slot will be jamma as will the jamma board, the U4 SHOULD by MVS wired but it's worth checking since it's been toyed with. You should need an adapter for jamma board to mvs cab, many adapters are for mvs 4 / 6 slot into jamma cab.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

Wait!!! That’s a really good point!!!

If this cab was used for MAME previously, perhaps it’s JAMMA wired rather than MVS?? Could that cause sound issues??

How could I tell which way it’s wired?

@sven666 , you might already know the answer :)
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

yosai wrote: April 15th, 2021, 6:18 pm The monitor requires 100v.
Ah, of course! Thanks.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by thegreathopper »

ChrisBEANS wrote: April 15th, 2021, 6:48 pm Wait!!! That’s a really good point!!!

If this cab was used for MAME previously, perhaps it’s JAMMA wired rather than MVS?? Could that cause sound issues??

How could I tell which way it’s wired?

@sven666 , you might already know the answer :)
Yes it would make a big difference, try a jamma board like your Atomiswave if the sound is ok on that it’s wired for Jamma and not MVS.
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Re: SNK U4 - Screen crackles and dies (help!!)

Post by ChrisBEANS »

If it is MVS wired, and I plug the AtomisWave in without an adapter, it’ll die though won’t it?
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