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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Wed Oct 03, 2018 8:57 pm 


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Joined: 31 Mar 2015
Posts: 174
Location: Netherlands
Can anyone help me with my XM29?

I just got my setup up and running again after moving it around and doing some home construction, and finally I got to testing my XM29 properly.
I noticed that when the monitor is powered ON from a cold state, there is a power cycle after about 1 minute.
This is just a split second and when it had done it once, I can leave it running all night without a single issue.
Other than that it has a beautiful picture and quite good geometry.

Here you can see it at the end of the video;
https://youtu.be/nbXjpHVvXak


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Wed Oct 03, 2018 10:32 pm 



Joined: 04 May 2014
Posts: 191
Location: germany
PascalP wrote:
Can anyone help me with my XM29?

I just got my setup up and running again after moving it around and doing some home construction, and finally I got to testing my XM29 properly.
I noticed that when the monitor is powered ON from a cold state, there is a power cycle after about 1 minute.
This is just a split second and when it had done it once, I can leave it running all night without a single issue.
Other than that it has a beautiful picture and quite good geometry.

Here you can see it at the end of the video;
https://youtu.be/nbXjpHVvXak


Damn..this actually can be everything...transistor going nuts and loosing voltage on one of the 5 billion boards that are installed in there, broken caps or just a cold solder joint somewhere.
I would have someone check it for you to make sure it does not get worse


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Thu Oct 04, 2018 1:31 am 



Joined: 26 Feb 2010
Posts: 410
Is this consistent? Always after 1 minute and it’s the same behavior?

I’ve seen this sort of things happen with BVMs and it was the spark gap. I’m just guessing though.

I would double check the connections between the boards to ensure nothing has come loose.


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Thu Oct 04, 2018 4:43 am 


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Joined: 31 Mar 2015
Posts: 174
Location: Netherlands
philexile wrote:
Is this consistent? Always after 1 minute and it’s the same behavior?

I’ve seen this sort of things happen with BVMs and it was the spark gap. I’m just guessing though.

I would double check the connections between the boards to ensure nothing has come loose.


Have seen it a few times over the past few days, and seems to be consistent when the monitor is ‘cold’.
What do you mean with the spark gap?


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Thu Oct 04, 2018 4:45 am 


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Joined: 31 Mar 2015
Posts: 174
Location: Netherlands
svensonson wrote:
Damn..this actually can be everything...transistor going nuts and loosing voltage on one of the 5 billion boards that are installed in there, broken caps or just a cold solder joint somewhere.
I would have someone check it for you to make sure it does not get worse


Yeah maybe I can contact the repair close to me from Germany, he fixed your XM29 as well right?


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Thu Oct 04, 2018 9:18 am 



Joined: 04 May 2014
Posts: 191
Location: germany
PascalP wrote:
svensonson wrote:
Damn..this actually can be everything...transistor going nuts and loosing voltage on one of the 5 billion boards that are installed in there, broken caps or just a cold solder joint somewhere.
I would have someone check it for you to make sure it does not get worse


Yeah maybe I can contact the repair close to me from Germany, he fixed your XM29 as well right?

Yes, he did. In my eyes a really good crt tech


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Thu Oct 04, 2018 12:58 pm 



Joined: 26 Feb 2010
Posts: 410
PascalP wrote:
What do you mean with the spark gap?


Here is an explanation of spark gaps:



These are protective devices intended to breakdown and divert excessive voltage away from the CRT (usually).

This is rarely due to a defective sparkgap or gas discharge tube but rather is a safety mechanism like a fuse designed to protect the internal electrodes of the CRT if the focus or screen voltage should become excessive. The sparkgap breaks down first and prevents internal arcing in the CRT. These sparkgaps may be built into the CRT socket as well.

Arcing at a sparkgap or a glowing or flashing discharge tube may be accompanied by total loss of picture or bad focus, brightness or focus fluctuations, or any of a number of similar symptoms. A common cause is a breakdown inside the focus divider (usually part of the flyback or tripler) but could also be due to excessive uncontrolled high voltage due to a failure of the B+ regulator or HOT snubber capacitor, or (ironically) even a short inside the CRT.

Spark gaps may be actual two or three pin devices with seemingly no insides, part of the CRT socket, or printed on the circuit board itself.

Gas discharge tubes look like small neon lamps (e.g., NE2) but could be filled with some other gas mixture to provide a controlled higher breakdown voltage.

Therefore, like a fuse, don't just replace or disable these devices, locate and correct underlying problem. The CRT makes an expensive fuse!




You should take it to a tech if there is one in your area.


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Sat Oct 06, 2018 2:42 pm 


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Joined: 27 Apr 2015
Posts: 638
Location: Bellingham, WA
PascalP wrote:
Can anyone help me with my XM29?

I just got my setup up and running again after moving it around and doing some home construction, and finally I got to testing my XM29 properly.
I noticed that when the monitor is powered ON from a cold state, there is a power cycle after about 1 minute.
This is just a split second and when it had done it once, I can leave it running all night without a single issue.
Other than that it has a beautiful picture and quite good geometry.

Here you can see it at the end of the video;
https://youtu.be/nbXjpHVvXak


If it happens once after 1 minute every time. That is a good thing for diagnostics.

To me it sounds like a leaky capacitor and your problem will most likely get worse when that capacitor runs out of fluid.

I would take the back off the unit and inspect the PSU board leading from the power cord. Look for bulging capacitors and leaking electrolytic fluid around the capacitor legs.

If you are getting this occurrence every time after 1 minute you can temporarily fix the broken capacitor by freezing the pcb board and problem capacitor with an upside down can of duster. (Wear gloves)

If after freezing the psu capacitors causes the issue to go away after 1 minute you can identify your issue on that board.

If it doesn’t fix your issue, go to the next PCB and look for bulges, leaks, freeze and test repeat.

If you happen to easily find your bulging capacitor or leak around it’s legs. Look for voltage and uf on the capacitor and you can order from many places online.
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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Sat Oct 06, 2018 3:34 pm 



Joined: 26 Feb 2010
Posts: 410
It’s not a bad idea to check the capacitors, but this really doesn’t sound like that is the issue based on my own experience.

If you’re going to open up the monitor I would turn off all the lights in the room and face the back of the display. Keep an eye out for a flash of light inside the unit at the time the tube turns off. If you see that then you’ll know it’s the spark gap and hopefully you’ll also have an idea of where it’s located. On the Sony D32s it’s on the neckboard.

This should still be taken to a technician for a proper diagnostic.

Good luck


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Sun Oct 07, 2018 6:59 pm 



Joined: 07 Oct 2018
Posts: 1
Hi dear owners of those greatfull monitors
I've got an XM29 + in an arcade cab since 5 years and recently I hear a very high whistle when I play in 15khz. It does not occur on resolutions higher than 640x480. I was told that it could come from coils that would vibrate at 15khz and would be audible. I tried to touch the components with a stick to see if the noise stopped but since I do not know where these reels are, it's a bit difficult. Can someone tell me where I should look? It seems to me that the sound comes from the PCB on the right when we look at the monitor from behind. I was also told about the very high voltage module that can vibrate. What do you think ?


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Wed Oct 24, 2018 5:21 pm 



Joined: 30 Jul 2017
Posts: 72
Does anyone know if there is a way to check the hour count on the XP29 or XP29+? Or do these not have that feature?


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Thu Oct 25, 2018 1:47 am 



Joined: 04 Jun 2015
Posts: 199
Sefirosu789 wrote:
Does anyone know if there is a way to check the hour count on the XP29 or XP29+? Or do these not have that feature?


Unfortunately the NEC XM / XP monitors don't record the hours used.


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Thu Oct 25, 2018 1:44 pm 



Joined: 30 Jul 2017
Posts: 72
xga wrote:
Sefirosu789 wrote:
Does anyone know if there is a way to check the hour count on the XP29 or XP29+? Or do these not have that feature?


Unfortunately the NEC XM / XP monitors don't record the hours used.


Didn't think so, but thought I would double-check. Thanks.


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Tue Nov 13, 2018 1:52 am 


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Joined: 19 Nov 2016
Posts: 6
Hi folks, I lucked into a pair of XM2950s recently. I bought both as not working and got a really great deal because it turns out that one of them is working fine and the issue was in the settings. That one one would power on, but the tube wouldn't light up at all and thus it appeared the screen wasn't working. That turned out to simply be a dip switch setting. Interestingly, in bank 1, if you set pin 7 to ON, it will shut off the screen similar to how pin 4 will mute the audio. I suspect this is related to the monitor looking for external control (what the pin specifies) and then displaying nothing (like a video mute, which is mentioned in the external control options table) if it doesn't find any. I'd be interested to hear if anyone has any other info on that particular situation.

The second one, however, was displaying a fuzzy image and I was wondering if anyone here as seen a similar issue. It was suggested to me by a friend that the problem is somewhere with the AC. Does anyone happen to have any thoughts? Here are a couple photos:
Spoiler: show
Image
Image


Back to the first one which is working, I'm also having an issue on RGB, where the image is not covering anywhere near the full screen. This could be an underscan setting (unfortunately I just picked up a remote on ebay, but don't have one yet) but the image is on the lower left of the screen rather than centered, so I'm not sure if that's the issue. Using S-video, I have no issues though, so I'm convinced this is a setting, somewhere. Has anyone seen something similar (note you may have to turn up the contrast/brightness to see the problem, but generally, just note that there is a huge gap between the image and the plastic bezel)?
Spoiler: show
Image


Finally, at the beginning of the thread, someone asked for the dip switch settings list. My monitors happened to have this written on the back, so I snapped a photo for anyone that may need them for whatever reason. I have not been able to find a complete service manual, nor have I been able to find a users manual at all, so at least folks can see the settings if they need them and their monitor was scratched or damaged such that the printed back was unreadable:
Image


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Tue Nov 13, 2018 2:40 am 



Joined: 26 Feb 2010
Posts: 410
I’ve seen that sort of fuzz with PVMs and it was due to capacitors. Do you have an ESR metter?


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Tue Nov 13, 2018 6:21 pm 


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Joined: 19 Nov 2016
Posts: 6
philexile wrote:
I’ve seen that sort of fuzz with PVMs and it was due to capacitors. Do you have an ESR metter?

Unfortunately I do not. My route to getting this fixed would be to take it to a guy I know locally who repairs electronics (and has done work on my Astro City monitors as well as my other PVMs). But was just trying to get a sense of how involved this repair work might be.


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Thu Nov 15, 2018 12:49 pm 



Joined: 24 Jul 2012
Posts: 100
Hi

I've came to the oportunity of getting a NEC XM37 monitor, the normal one (non plus or xtra) for a really good price inside my country

I think it's a multisync monitor, but the seller says he never has tried any 15KHz source... I trust him as I've bought from him before and he's selling his own monitor

So, a couple questions here:

1) Do it support 15KHz sources?
2) How much is the maximum resolution? He says 720p...
3) Which connections are available as inputs?

Thanks in advance


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Thu Nov 15, 2018 3:10 pm 



Joined: 04 Jun 2015
Posts: 199
Nodoyuna wrote:
Hi

I've came to the oportunity of getting a NEC XM37 monitor, the normal one (non plus or xtra) for a really good price inside my country

I think it's a multisync monitor, but the seller says he never has tried any 15KHz source... I trust him as I've bought from him before and he's selling his own monitor

So, a couple questions here:

1) Do it support 15KHz sources?
2) How much is the maximum resolution? He says 720p...
3) Which connections are available as inputs?

Thanks in advance


What is the actual model # of the monitor? e.g. XM-3750


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Thu Nov 15, 2018 4:41 pm 



Joined: 24 Jul 2012
Posts: 100
xga wrote:
What is the actual model # of the monitor? e.g. XM-3750


Hi, it's model XM-3750G(A)


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Thu Nov 15, 2018 10:29 pm 



Joined: 04 Jun 2015
Posts: 199
Nodoyuna wrote:
xga wrote:
What is the actual model # of the monitor? e.g. XM-3750


Hi, it's model XM-3750G(A)


The XM37 / XM-3750 model does not support 15KHz. The horizontal sync range on the XM37 / XM-3750 is 24KHz to 50KHz. Some people have used a PC running GroovyMAME combined with the 120Hz trick to get this monitor to display 15KHz content, but you would need some sort of upscaler to use a console.


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Thu Nov 15, 2018 10:55 pm 



Joined: 24 Jul 2012
Posts: 100
What is the máximum resolution?


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Thu Nov 15, 2018 11:26 pm 



Joined: 04 Jun 2015
Posts: 199
Nodoyuna wrote:
What is the máximum resolution?


Maximum resolution of the XM37 / XM-3750 is 1024 x 768 @ 60Hz refresh.

I should also add that my comment above regarding the 120Hz trick has been done on the XM37 / XM-3750's brother, the XP37 / XP-3778. The XP37 / XP-3778 also does not sync down to 15KHz horizontally, but will sync from 24KHz up to 78KHz. They both sync from 40Hz up to 120Hz vertically, but I am not sure if the 120Hz trick relies on the XP37 / Xp-3778's ability to sync higher horizontally.


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Fri Nov 16, 2018 12:11 pm 



Joined: 24 Jul 2012
Posts: 100
Seller says It can support 720p


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Sat Nov 17, 2018 1:16 am 



Joined: 04 Jun 2015
Posts: 199
Nodoyuna wrote:
Seller says It can support 720p


1280x720 @ 60Hz should be within its limits I would think.


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Sat Nov 17, 2018 9:19 am 



Joined: 24 Jul 2012
Posts: 100
xga wrote:
Nodoyuna wrote:
Seller says It can support 720p


1280x720 @ 60Hz should be within its limits I would think.


This is nice!

I'm supossing 1080i or 1080p would be out of limits, right?


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Sat Nov 17, 2018 2:29 pm 



Joined: 04 Jun 2015
Posts: 199
Nodoyuna wrote:
xga wrote:
Nodoyuna wrote:
Seller says It can support 720p


1280x720 @ 60Hz should be within its limits I would think.


This is nice!

I'm supossing 1080i or 1080p would be out of limits, right?


1080i *should* be fine, but 1080p would be unlikely. You've got to remember that this is a 4:3 monitor, so you might be better off with a widescreen CRT TV that will do HD and Full HD resolutions if you're wanting to display a lot of 16:9 content.


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Mon Nov 19, 2018 11:18 am 



Joined: 24 Jul 2012
Posts: 100
Yes, I understand 720p, 1080i and 1080p are 16:9 resolutions, but I always like to know the limits of the monitors... :)

Thanks a lot for the info and answering my questions


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Tue Nov 20, 2018 6:00 am 


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Joined: 27 Apr 2015
Posts: 638
Location: Bellingham, WA
Nodoyuna wrote:
Yes, I understand 720p, 1080i and 1080p are 16:9 resolutions, but I always like to know the limits of the monitors... :)

Thanks a lot for the info and answering my questions


XGA is your max resolution.

I would reccomend an OSSC. You will most likely be able to use 3x mode for perfect integer scaling. 320 x 3 = 960 , 240 x 3= 720

You could zoom resolution with your CRT to full screen and still maintain aspect.

(Your native is 1024x768, Your image on a 3x scale for 240p would be 960x720. Underscan and zoom)

Enjoy your TV for its 4:3 benefits.
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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Wed Nov 21, 2018 5:29 am 



Joined: 23 Mar 2016
Posts: 13
Location: USA
I'm in the process of replacing the electrolytic caps on an XP37 (XP-3790) I recently picked up, and I've possibly run into a slight issue.

While working on the Chopper Reg PCB (PG319B), I noticed that the transistor in location Q1 is missing but there are definitely still leads in the through-holes. It looks like the legs were snipped because they're all pretty level and straight upright, and I know I didn't do it.

Before I go down the path of possibly replacing a part that was removed at the factory, I was hoping another XP37 owner could check theirs for me and see if they have a transistor at Q1--it's adjacent to CNB01 which connects to CN406 on the Horizontal Deflection PCB. If there's one there, could you get the value for it? I'm assuming it's a 1202 like the others on that circuit, but just in case it's not.

Or if anyone has a schematic handy, that'd be helpful, too.


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 Post subject: Re: NEC XM/XP 29/37 Pro/Xtra Thread
PostPosted: Wed Nov 21, 2018 9:30 am 



Joined: 22 Dec 2010
Posts: 210
My 3778G is partially disassembled awaiting a recap so I should be able to easily check for you although due to the fact that they are slightly different models I can't guarantee either way that what I find in mine should be the same in yours.

EDIT: Just had a quick look and none of the boards or connectors seem to match the numbers on yours. Could you take a photo of the board that you are referring to and maybe a close up of the section with the missing part so that I can see if it is anything like the one in mine?


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