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bug flying sound from monochrome green monitor

lucasdaytona

lucasdaytona

Veteran Member
Joined
Jul 23, 2011
Messages
564
Location
Brasil
Hello all,

Due to my lack of experience, I have a question:

I have a monochrome green monitor here(it came with a XT clone), and it keeps emitting a buzz sound, looks like it comes from the tube. When I'm playing some games (prince of persia for example) the sound changes when the screen changes a lot, is that normal? The monitor is working 100%, I just had to do a small adjust in H/V inside, but all displays ok. A lot of time in the past, I had a monochrome VGA monitor, and it had a similar buzz noise. What do you guys think?

Thanks!
 
The tube is a M31-334GH/B, on the flyback transformer is written: 31671 SR-913.

I did a small research, and there's a compatible list that says that a 114/150 flyback will work. Looks like my monitor uses the same flyback of a Philips monitor.

And now that you said, I'm hearing the noise from the flyback ;)
 
Is the buzz a high or low frequency ?
It does, as Stone pointed out, sound like a loose winding in the flyback.
However, does the monitor have a speaker ? Is it a 5151, if not, what make model ?
If it's a 110V supply model, are you running it on 220 with a true step-down transformer, or the electronic kind, like for hairdryers and such ?
patscc
 
Assuming you're talking about a very high-pitched noise, a certain amount of flyback 'ringing' is normal. Some people are more sensitive to it than others, and some monitors make more noise than others. I imagine the reason you're noticing it more on monochrome monitors because they use a different scanning frequency than higher-res VGA displays and such.
 
Looks like the buzz is a high frequency. The monitor does not have a speaker, it's a generic green monitor, made by a Brazilian company, called VIDEOCOMPO, it's a 50/60Hz model, 22W, auto selecting 110v~220v, I'm using 127v (Brazil standard) at moment, no converters or anything(Tried another power source, same results).
 
Old Thrashbarg said:
Assuming you're talking about a very high-pitched noise, a certain amount of flyback 'ringing' is normal. Some people are more sensitive to it than others, and some monitors make more noise than others. I imagine the reason you're noticing it more on monochrome monitors because they use a different scanning frequency than higher-res VGA displays and such.
Click to expand...

The computer have two very loud fans, and the monitor noise is very audible, even with the speaker playing. But I could live with that, if that's normal.
The sound is a mix of a cicada and a cricket, but in Brazil a Cicada do a different noise ,like this, but the monitor have a continuous noise, like in the end of video.
 
The picture is normal. I don't know what is the video mode that I use, but every game I try, or just plain DOS, and everything works well.
 
It could also be corona noise. Take the cover off the monitor, power it up in a very dark room and look carefully at the innards. If you see a faint blue light around the high-voltage anode lead (or smell ozone), you've got a corona leak. They usually can be patched with a a bit of silicone caulk (RTV) or even a dab of glypt.
 
patscc said:
Good call, but what's glypt ?
patscc
Click to expand...

Okay, so I'm showing my age--"Glypt" is a nickname for Glyptal insulating varnish--still used in the aerospace racket, but available from GC in small bottles:

GC-Electronics-10-9002-A.jpg


Surely you've seen it--now you know what it's called.
 
I will try to see the faint blue light at night, my house have a lot of windows, it's dark only at night.
 
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