Hello,
I have an NEC MultiSync XP29 Plus that started having an issue with the RGB Inputs (both 1 and 2) when sending a 31kHz or higher source. The display is shrunk horizontally (from left to right, only), and you cannot expand much to get anywhere near the edge of the display. On top of that, there is an alarming burning smell (I cannot tell what exactly the material is from the smell, but you can smell it from 8 feet away). There are no issues with the picture other than the shrunk image. I've also looked through the holes in the dark and do not see any arcing.
This issue started after I was testing changing modes from the XBOX 360 VGA output - 1024x768 to 1280x1024. When I next powered on a Dreamcast with VGA output (640x480), I noticed this issue. And it persists no matter the source.
There are no issues with the picture and no smell when using the Video 1 or 2 inputs - Svideo OR Composite.
Could anyone help point me in the right direction before this beast explodes? I'm guessing issue on the deflection board?
Thank you!
MultiSync CRT 31kHz+ Shrunk and Burning Smell
Re: MultiSync CRT 31kHz+ Shrunk and Burning Smell
I can confirm that 15khz works fine on the two RGB inputs. Once I switch to 31khz(480p or 640x480) the image shrinks in, and it seems that it only recognizes 31khz even if you raise the resolution to something that should require a higher horizontal frequency. The smell starts a few minutes after; there is no smoke.
My first thought is weak power supply. But - it could be my imagination - I think the smell is strongest from the horizontal deflection board side. The power supply is on the opposite side. But then again, the thing has so many fans it could be blowing the smell from anywhere. Could a weak/bad power supply cause something in the deflection board to make a burning smell?
My first thought is weak power supply. But - it could be my imagination - I think the smell is strongest from the horizontal deflection board side. The power supply is on the opposite side. But then again, the thing has so many fans it could be blowing the smell from anywhere. Could a weak/bad power supply cause something in the deflection board to make a burning smell?
Re: MultiSync CRT 31kHz+ Shrunk and Burning Smell
If something's burnt, you'll probably be able to see it. First thing you should do is open it up and look for damaged parts.
Re: MultiSync CRT 31kHz+ Shrunk and Burning Smell
I opened it up and looked, I don't see anything. Even with it on. I also cannot detect any excessive heat from the deflection board. Freaking thing has a larger deflection circuit than an entire 21" PC monitor.
I noticed the Toshiba chip on the back is dangerously hot to the touch. But I don't smell anything coming from it. I believe it's a sync separator chip - which is a red flag, since it only shows 31khz for anything 31khz and higher. But, according to datasheet it's only for Svideo or composite, and I'm having no issues with 15khz.
I noticed the HSTAT pot on the top by itself has whiteout mark but it's not sealed in original position. Along with the static convergence, I believe this is related to high voltage to the flyback? No issues with static convergence though. And the monitor easily hits 200nits without looking out of spec or washed out.
There isn't a service manual for this thing, so it's all guess work. I may just leave it alone until something completely breaks down.
I noticed the Toshiba chip on the back is dangerously hot to the touch. But I don't smell anything coming from it. I believe it's a sync separator chip - which is a red flag, since it only shows 31khz for anything 31khz and higher. But, according to datasheet it's only for Svideo or composite, and I'm having no issues with 15khz.
I noticed the HSTAT pot on the top by itself has whiteout mark but it's not sealed in original position. Along with the static convergence, I believe this is related to high voltage to the flyback? No issues with static convergence though. And the monitor easily hits 200nits without looking out of spec or washed out.
There isn't a service manual for this thing, so it's all guess work. I may just leave it alone until something completely breaks down.
Re: MultiSync CRT 31kHz+ Shrunk and Burning Smell
Does anyone happen to know where the monitor gets the sync details/feedback from that is reported to the menu? Maybe I can start there and work back and look for shorted components? As I said, even 1280x1024 now reports 31khz when it should be 63khz.
I'm going to try a 33khz interlaced signal (1080i), and see if it's progressive scan related.
Edit/update: 1080i has the same problem. But I suppose I lied about it not recognizing the correct scan rate. It recognized 1080i as 33khz, but the image is squashed and non expandable.
Double edit: Would appreciate if anyone has any schematics or some legendary service manual - even if it is related to the XM29 instead. My assumption is, since the picture is near perfect, that the power supply voltage when switching scan rates is low, OR something in the auto-sync circuitry is blown.
Thank you!
I'm going to try a 33khz interlaced signal (1080i), and see if it's progressive scan related.
Edit/update: 1080i has the same problem. But I suppose I lied about it not recognizing the correct scan rate. It recognized 1080i as 33khz, but the image is squashed and non expandable.
Double edit: Would appreciate if anyone has any schematics or some legendary service manual - even if it is related to the XM29 instead. My assumption is, since the picture is near perfect, that the power supply voltage when switching scan rates is low, OR something in the auto-sync circuitry is blown.
Thank you!