Disaster!! (NEC 4PG Multisync)

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ChrisBEANS
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Disaster!! (NEC 4PG Multisync)

Post by ChrisBEANS »

Time for another one of my 'bloody hell, I broke it!!' threads.

This one is pricey, and REALLY upsetting.

So, I was very lucky to pick up an NEC 4PG multisync monitor. I've been rearranging my setup today, and having a great time doing it.

The set has two RGB inputs. RGB1 is a VGA connection, and RGB2 is BNC.

Had a CPS2 multi running on RGB2 via a supergun, and it's been brilliant. The picture's been beautiful. (I really wish I'd photographed it, it really is an amazing picture!)

Tried an AtomisWave on RGB2 via a VGA to BNC cable, all good.

Then, pointlessly, just to see, I tried the AtomisWave on RGB1 with a VGA to VGA cable, and the picture came up great, then began to colapse inwards.

Now even on RGB2, back on the supergun that was showing a perfect picture previously, the picture has collapsed.

Image

I was literally finishing setting up what is effectively the last piece of my ultimate setup, when I killed it by **** about.

I've already messaged the mighty @grantspain , but sadly he doesn't touch these monitors. Any suggestions who might??
Last edited by ChrisBEANS on August 1st, 2022, 6:20 pm, edited 2 times in total.
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Re: Disaster!! (NEC PG4 Multisync)

Post by ChrisBEANS »

I am genuinely gutted. This really was the final physical piece to complete my setup.

What a knob!!!!!
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Re: Disaster!! (NEC PG4 Multisync)

Post by MrSandman »

Sorry to hear, hope you will be able to fix it.
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Re: Disaster!! (NEC 4PG Multisync)

Post by geotrig »

That's **** dude :( can't really help , might be best trying to find an old crt repair guy around ,even at that they mightn't go at it.

Was there any pop or anything? Coul be some bad caps of transfoemermaybe with hori collapse
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Re: Disaster!! (NEC 4PG Multisync)

Post by ChrisBEANS »

geotrig wrote: August 1st, 2022, 8:00 pm That's **** dude :( can't really help , might be best trying to find an old crt repair guy around ,even at that they mightn't go at it.

Was there any pop or anything? Coul be some bad caps of transfoemermaybe with hori collapse
It appears it might be `the horizontal output transistor'... There's a possibility it may be looked at, but yet to be confirmed.

In the mean time, look at this and imagine how sweet it would have been if I wasn't such an idiot!!!

Image

Sadness
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Re: Disaster!! (NEC 4PG Multisync)

Post by ChrisBEANS »

I've also found an Espgaluda 2 too, which is the last PCB on my list, so this is double sad!!

However... It appears that a hero has stepped forth. I'll update if it's fixable!!
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Re: Disaster!! (NEC 4PG Multisync)

Post by Monstermug »

That monitor looks sweet there. Its gonna blow away the picture quality on your two cabs. Dont worry im more worried about if its easy to open it up and having the space for it than fixing it. One of the perks of buying stuff from me. You get a discrectional lifetime warranty 😅
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Re: Disaster!! (NEC 4PG Multisync)

Post by PunkicCyborg »

To be honest, doesn't sound like you did anything wrong. these monitors handle just about anything you throw at it. I have a XM 29 and hook up all kinds of things like arcade boards and Japanese computers to it and it adjusts the sync automatically to whatever you plug in. It's just old. I also suggest finding somebody who is like an old CRT guy. You might also be able to open it up and look around for anything that could have shorted out.
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Re: Disaster!! (NEC 4PG Multisync)

Post by ChrisBEANS »

If you can fix it… we might have to get married!! I’ll even be the wife!!

It was fantastic before I blew it up!! AW in 31kHz goodness and the CPSII looked incredible on it.

Once it’s all hooked up to a scart switch, and the shelves are all cable managed, it’s going to be the dream.

I ‘think’ the Windy II is going now I’m set for 31kHz too
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Re: Disaster!! (NEC 4PG Multisync)

Post by ChrisBEANS »

PunkicCyborg wrote: August 5th, 2022, 4:53 pm To be honest, doesn't sound like you did anything wrong. these monitors handle just about anything you throw at it. I have a XM 29 and hook up all kinds of things like arcade boards and Japanese computers to it and it adjusts the sync automatically to whatever you plug in. It's just old. I also suggest finding somebody who is like an old CRT guy. You might also be able to open it up and look around for anything that could have shorted out.
I mean, I didn’t think I’d done anything wrong… it’s supposed to be good for VGA up to 1024x768, and the AW displayed great at 31kHz via a VGA to BNC cable between the AW and RGB2 input.

Perhaps the VGA port on the AW outputs some strange signal that’s not supported?!

It had been on all day with various inputs on the BNC ports, but as soon as I plugged the VGA in it died.

Well, I say ‘as soon as’, very quickly afterwards.

Possibly a blessing in disguise. If the mighty @Monstermug can get this bad boy up again, new caps and nice quiet fans, it’ll be good for another 30 years!!!
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Re: Disaster!! (NEC 4PG Multisync)

Post by Monstermug »

I think he was messing around with the 75ohms protection switches and that could have stressed out deflection transistors. That combined with the unknown output of the atomiswave setup he has pluged into the rgb port and switching it to 15k resolution? Who knows. I fix it and then try to see if i can blow it again. If i cant replicate the fault then it could just have well been a faulty component
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Re: Disaster!! (NEC 4PG Multisync)

Post by ChrisBEANS »

Monstermug wrote: August 6th, 2022, 1:16 pm I think he was messing around with the 75ohms protection switches and that could have stressed out deflection transistors. That combined with the unknown output of the atomiswave setup he has pluged into the rgb port and switching it to 15k resolution? Who knows. I fix it and then try to see if i can blow it again. If i cant replicate the fault then it could just have well been a faulty component
None of the above…

RGB 2 is BNC inputs.
So the AW displayed perfectly at 31kHz via VGA to BNC ON the RGB 2 input. That was with all switches on the RGB 2 input set to 75ohms.

Then the supergun and Megadrive would display perfectly on RGB 2 via scart and then a scart to BNC adapter, but only if the switches were set to high.
If the switches were set to 75ohms, the image wouldn’t display.

RGB 1 is a VGA input.
The protection switch on RGB 1 was set to 75ohms, and the only time I used this input was the one occasion I ran a VGA to VGA cable between the AW and RGB 1.
The AW has the dips set to 31kHz at all times.

Picture came up apparently fine at first, and seconds to maybe a minute or so later collapsed in.

Just trying to be as clear as possible so we can work out where I went wrong, so I don’t do it again :lolno:



As above, might well be a blessing in disguise. If the mighty MM can get it going again, then it’ll have the benefit of new quiet fans and some new caps, and I’ll be set for decades 8-)
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Re: Disaster!! (NEC 4PG Multisync)

Post by ChrisBEANS »

In case it’s relevant, I ran the AW at 31kHz on RGB 2 for about ten minutes with no apparent issues.

I’d been running the supergun on RGB 2 at 15kHz for several hours that day, again with no issues.

I had physically moved the monitor around that day, but always carefully and gently.

I first moved it up on to the shelf, and ran it at 15kHz for some time. No issues.

Then I turned it on it’s side and ran a vertical shooter for an hour or so without issue.

Then back to yoko and as above it ran for hours without issue.

It was only after I tried the VGA to VGA connection that it went tits up.

Frustratingly, I’d actually finished setting everything up, and I thought I was done with knobbing about for the day, when I decided to go for the VGA to VGA connection so that I could avoid unnecessarily unplugging the BNC connectors, but still fire up a 31kHz game to smugly show the whole set up off.

I guess pride is a sin for a reason!
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Re: Disaster!! (NEC 4PG Multisync)

Post by Monstermug »

I doubt you can blow it up with correct wiring. Sometimes wiring aren't standardise and that could damage the display. I.e if switch voltages on the scart connector isnt wired to the correct pin (or a wrong adapter or cable for the scart) that may cause a problem. I've seen a lot of x68k video cards broken due to people plugging in the wrong pinout for the video port.
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Re: Disaster!! (NEC 4PG Multisync)

Post by ChrisBEANS »

We’ll investigate as a team 8-)
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Re: Disaster!! (NEC 4PG Multisync)

Post by yosai »

Let **** Kick Together. :awe:
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Re: Disaster!! (NEC 4PG Multisync)

Post by ChrisBEANS »

@yosai just won the topic

Well played 8-)
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Re: Disaster!! (NEC 4PG Multisync)

Post by Monstermug »

Well after spending two hours at Mr Beans pad, of which about 15 minutes was to remove the Horizontal Output PCB and the rest playing Esperade and snow bros, not to mention, avoiding his dog,

After removing dozens of screws, the monitor back plastic came off revealing the insides. We both was very surprised at how clean it looked inside (not a spec of dust) and how well designed it was for easy maintenance. Parts opened up on hinges allowing super easy access

Anyway, we tried to take out the input board which looked easy until we ran into an earth cable that was screwed into the plastic in an extremely hard to reach place. So rather than proceeding any further, I was happy to dismiss that it wasn't an input board fault for now. At this point, Mr Beans was shaking his head and mumbling, "this isn't getting fixed is it". I tried my best to assure him that it will while trying to figure out what was what. First time I opened a NEC broadcast monitor. But then again, I usually have no idea what to expect on anything I fix.

Next the main chassis was at my attention but that was buried deep inside the casing. Again, I can faintly hear Mr Beans mumbling "this isn't getting fixed ever" as we had a brain storming session on how to remove the high voltage anode even if we could get to the chassis without me having to spend the night there. Anyway. after relaxing on his sofa and reading the schematics another pcb caught my attention. It was a small pcb labelled H-OUT pcb. Following Horizontal wires on the neck board back lead to this pcb. Remarkable. It's not connected to the main chassis!

Image

At this point Mr Bean's gave me a Multi meter which I had to work out how to use as I am so used to using my own Fluke. Anyway, we found that one of the diodes, it looked like a transistor, but only two legs, was shorted. That needed replacing so we quickly removed it. Unfortunately, someone previously has had a go at this, and the screw was damaged. We cut it off and out went the pcb.

Image

I left Mr Beans the task of trying to get that screw out, while I quickly escaped with the part I needed to repair.

Image

After taking it home, it looks like the Horizontal output transistor had failed catastrophically including the connected Power Diode connected to it as well. This was after I wasn't satisfied that the Diode cannot be the only thing that failed.

Image


Two parts on order and can safely say it should fix the fault. Mr Beans seems sceptical of my abilities but then again, only by testing it, will we surely know.... :oops:
Last edited by Monstermug on September 26th, 2022, 11:00 pm, edited 1 time in total.
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Re: Disaster!! (NEC 4PG Multisync)

Post by ChrisBEANS »

That dog is unavoidable!!!

No scepticism of you, sir, but a healthy scepticism that anyone without specific knowledge can just open up one of these bad boys, work out what’s wrong, why, and how to fix it…

Much more confident now I’ve seen you work :hinthint: :hinthint:

No so confident on your ESP.Ra.De. abilities though
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Re: Disaster!! (NEC 4PG Multisync)

Post by Monstermug »

ChrisBEANS wrote: September 26th, 2022, 11:19 am That dog is unavoidable!!!
I loved how he pulled a sad cute face when I just ignored him :lol:
ChrisBEANS wrote: September 26th, 2022, 11:19 am
No scepticism of you, sir, but a healthy scepticism that anyone without specific knowledge can just open up one of these bad boys, work out what’s wrong, why, and how to fix it…
Anyone can if they follow my general rule of fixing anything. Maybe I should write a book :think:
ChrisBEANS wrote: September 26th, 2022, 11:19 am
No so confident on your ESP.Ra.De. abilities though
I was just warming up! But then again, I usually get worst as I warm up :roll:

Anyway, updated that post with pics in case anybody else might need it to fix their NEC. Just make sure you order the right transistor unlike me :oops:
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