M1330 crazy buzzing - from the screen! (LED)

Hi all, I've been reading/lurking here for a little while as I had an M1330 inbound and wanted to get some additional info. I've read thru the thread(s) on "CPU whine" and other noises, but I'm experiencing something that I believe is different than this - but may be what some others have been struggling with too. Anybody else having this same screen-based noise problem? My apologies if this has already been discussed, I have been reading and searching here for a while and haven't come across folks concluding that they had the same issue.

Machine config:

• M1330 / T7500 2.2GHz / A04 / LED backlit screen
• 3GB RAM / 250GB 5400rpm Drive / 4965 A/G/N Wireless

Mine is a high-pitched buzzing sound, which I've concluded is actually coming from the lower edge of the screen. The noise I'm concerned about has similar symptoms to what some have described, but my conclusion is that at least in my case it must be some component or driver on the board for the display panel itself. I know that on some LED flashlights, there is a PWM (pulse width modulation) circuit used to "dim" the LEDs by actually flashing them at decreasing ratios of on/off time - and that in some LED driver designs this is actually audible.

Some symptoms/info:

• High(er) pitched "buzzing" sound, loudest at the base of the screen
• Increases in volume with decreased brightness adjustment
• Decreases in volume with increased/max brightness - but still very noticeable
• Noise changes (volume, not pitch) when I press on the black lower screen bezel
• At low brightness levels, I have some (eight?) vertical bright streaks - I assume from the backlight LEDs

I've confirmed its a Chi Mei screen, and I do have some mild "screen door" effect, or faint horizontal lines running across the screen - as well as some backlight bleed from the top edge. I'm not sure if I'd describe it as "grainy" although it's definitely not as smooth an appearance as the LCD I use with my desktop machine for the past many years. Color / contrast / brightness are excellent, overall the appearance is very nice.

Until this morning, I was thinking it was CPU whine, or something from the audio system because it almost seemed to be coming from the area of the left speaker. Only when I attached my desktop's monitor to experiment with a dual-monitor/expanded-desktop setup did I realize that the noise goes away completely when the screen goes off. <fn-F8> to the external monitor alone, and the noise instantly disappears 100%. Running dual or back the laptop, it kicks in again. I notice it on boot too, when the screen briefly toggles out on startup.

It's a shame really, otherwise a really nice little machine - mine has generally very good fit/finish. I love the idea of a barely-over-4lb machine that PCMark05's at just over 5000 (system) and 4200+ (graphics, with some tweaking! ), what a great little portable powerhouse! Unfortunately, the system is not viable/live-able for me with this buzz - it's extremely annoying and conflicts directly with my needs and usage for such a machine.

I have a second one coming probably late this next week, I'm really curious to see if it has the same issue, or if it's better <fingers crossed!>. Regardless, this particular machine is going back on the 21-Day Total Satisfaction (not!) guarantee.

 

That's more likely to be a problem with the inverter. The PWM frequency is generally under 1000 Hz (so it shouldn't be a very high pitch), and it goes away when the screen is at full brightness.

 

Send it back to dell!!

 

OK, sounds like I probably overstated the pitch of the sound. I downloaded a tone generator, and it's most similar to a 269hz sawtooth waveform - going by ear.

In addition, I get an occasional flicker (every 10-30 minutes) which kicks up the volume (level) but not the pitch of the tone. Likewise when I turn the screen down in brightness, the volume (level) gets higher at lower brightness - but the tone (pitch) stays the same at all times.

This morning, I had an interesting experience where I was "tweaking" the corners of the screen gently (moving the upper corners of the screen in opposite directions) and at one point the noise stopped completely. Unfortunately, when the noise stopped, the screen was showing VERY strong vertical bars of light, much like I'm seeing when the screen is turned down to minimum brightness.

Crazy! Regardless, there's clearly a problem with the screen/panel. I'm surprised that there haven't been more replies from folks saying they've experienced the same. Maybe I'm just "lucky."

 

Sounds like a fairly uncommon problem with your screen, just get dell to replace it

 

Will do! I just received an email from Dell that the second M1330 should be here Wednesday, hopefully that one will be a bit quieter!

 

My second M1330 showed up yesterday. Super quiet, no buzzing from the screen (yeah!!) and to top it off - a Toshiba panel!

I will say that without question the Toshiba image is "smoother" than the Chi Mei. No screen-door effect, or the thin horizontal lines across the screen like the Chi Mei. My CMO had fairly nasty backlight bleed from the top, and uneven lighting of the screen across the bottom. In general, the TMD panel is nicer, IMHO.

That said, I did note that the CMO had better contrast, meaning that the blacks were "blacker" and the midtones had better separation. I've played around with the NVidia settings a bit to tune the TMD panel, and while it's much better after some fiddling around, I do have to say that the TMD is "flatter" looking in general from a color perspective compared to the CMO I had.

"CMO I had" is the case, because that machine was picked up by Dell today for return/refund. The second machine is everything I hoped for and expected from an XPS laptop. Good stuff!

 

Yet another happy ending..
I also have said screen and no other LED back-lit to compare with but 120% happy with the end product that I have..

 

How can you find out the make of the pannel?

 

This have been posted many times now just to help you out goin to device manager monitor setting or download a program called SIW which will give you all info on your system..Google it

 

How long did it take to get the replacement ??? I'm waiting for one?
thanks