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RetepNamenots

macrumors 6502
Original poster
May 30, 2009
257
4
Hi all

I have two VGA cables. My first is simply a cheap one which I have been using for the past few months on my full HD (1080p) TV. I use a Mini DisplayPort to VGA adapter on my 17" Macbook Pro and have been able to get full HD output to my TV.

However, this cable was poorly shielded and I got some wavy lines from other TV inputs.

I've just got a new VGA cable, and this has far greater shielding (so that problem is fixed), however I cannot get it to go above a resolution of 1400x1050 - going to 1920x1080 @60Hz as I did with the other cable gives me a message from my TV - "Unsupported signal. Adjust your PC output."

When I try and use the 'Detect Displays' button in System Preferences, I don't see anything happen as a result...

Help!


Edit: After a bit of research, my new cable is actually an SVGA cable. It has the same pins, layout etc and as far as I'm aware it should work. Why doesn't it!?

Edit2: Tried another VGA cable, and that works. So my findings are that 'Super-VGA' cable doesn't work, at least by default. Any way I can fix this?
 

m85476585

macrumors 65816
Feb 26, 2008
1,226
4
VGA is a cable standard and a resolution. There's no such thing as a WUXGA cable, but you can probably find a VGA cable that supports WUXGA.

I think all those acronyms are kind of meaningless- it's easier to just refer to a resolution by numbers. Quick, how big is WQSXGA+, and can I play it on a WQUXGA display?

Also note that QVGA is quarter VGA, but QXGA is quad XGA.

I can't wait until WQUSXVGAWBNQVEQWE displays are out. I hear they have them in Japan.
 
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RetepNamenots

macrumors 6502
Original poster
May 30, 2009
257
4
do you know for sure that your TV is capable of 1080p?

And also try switching to 30Hz?


As I said in my original post, I have been using my TV at 60Hz at full HD (1920x1080) for the past few months - it is only with a replacement VGA cable that I am having problems.
 
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Macsavvytech

macrumors 6502a
May 25, 2010
897
0
it is impossible for you to have been using the tv as a display at 1080p vga simply doesn't support that a did you say have a dvi cable
 
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RetepNamenots

macrumors 6502
Original poster
May 30, 2009
257
4
it is impossible for you to have been using the tv as a display at 1080p vga simply doesn't support that a did you say have a dvi cable

My TV has been running at that resolution, I promise you. There is no 'upper limit' for the resolution that VGA can output.
 
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HLdan

macrumors 603
Aug 22, 2007
6,383
0
Would you like me to record a video and upload it as evidence?

Yes, please do. Make sure the video includes showing you plugging in your VGA cable from the Mac to the TV and show the resolution of 1920X1080 on the TV to confirm. But doesn't your TV have an HDMI port? Why a VGA only on a TV that supports HD? :confused:
 
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RetepNamenots

macrumors 6502
Original poster
May 30, 2009
257
4
Yes, please do. Make sure the video includes showing you plugging in your VGA cable from the Mac to the TV and show the resolution of 1920X1080 on the TV to confirm. But doesn't your TV have an HDMI port? Why a VGA only on a TV that supports HD? :confused:


Will do on Friday.

It's a brand new TV - I would've got a HDMI cable had I not already got the VGA adapter.
 
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m85476585

macrumors 65816
Feb 26, 2008
1,226
4
I've run 1280x1024@60Hz by VGA to various monitors on various computers (my MBP and two desktop PCs to a CRT or an LCD). I've connected my MBP to my 1080p TV with VGA to test out cables (I have at least 3 and most showed some ghosting. I think there was one good one).

According to Wikipedia, VGA can support up to 2048x1536px @85 Hz or more. The RAMDAC should be able to support whatever the maximum output resolution is 2560 by 1600, unless Apple specifies otherwise (which they don't).

Those of you claiming VGA can't support 1080p, what do you think the maximum resolution is?

Why use VGA? Some older HDTVs predate DVI/HDMI being common, or maybe all his HDMI/DVI ports are used by other devices. Obviously a digital connection would be better though.
 
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SDAVE

macrumors 68040
Jun 16, 2007
3,381
444
Nowhere
VGA does indeed support 1080p. Even higher than that.

Try replacing the cable.

If anyone says it doesn't, it's juts marketing hype.

Component will also support 1080p, but companies want you to migrate to HDMI and spend $$$.
 
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al2011

macrumors newbie
May 7, 2011
1
0
re:New VGA cable won't do 1920x1080?

A lot of VGA cable won't do that resolution because the cable does not fully implement all connection to 15 pins.

I run into the same problem after getting 2 pairs of longer cable (thus able to verify it's not a faulty cable) - and to cut the story short, I use a multimeter tester to test each pin connection.

The original short cable connects to all 15 pins.

The replacement cable does not implement 4 pins.

After returning the 'faulty' cable I brought along my multimeter tester and check vga cables before i purchase it - most of them have the short-cuts, 4 pins not connected. I did found one that fully implement 15 pins, but it is of bad quality and the image produced ghosts effect (it's a 7 meter cable) - thus, have to return it again.

After too many trips, I just settle for a hdmi cable.

It's not that vga cable limits the resolution - it's the short cut that the prevent newer monitors to send enough information to the video card to pick up it's native resolution.

Check wiki on vga .. some pins are for the monitor to send extra information to the video card and some of these can be ignore for older monitors, but newer monitor uses them.
 
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houstom1138

macrumors newbie
Jul 26, 2011
1
0
cheap cable

Thanks "al2011". Your explanation (4 of the 15 pins not even connected) was my solution. My PC (not MAC) can't tell what type of display I have when I use this new, cheap VGA cable but when I use a decent cable there's apparently some bi-directional communication that occurs and the PC correctly detects my monitor type and uses the right driver/resolution/everything. My eyballs thank you.

Tom
I'm a PC
 
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DWBurke811

macrumors 6502a
Jun 10, 2011
820
1
Boca Raton, FL
Why not just get a MDP>HDMI adapter from mono price for like $8? And a HDMI cable for another $5 or so? This will also carry audio to the TV, or if you're using the audio out on your Mac, they have MDP>HDMI cables for under $10(but, again, it won't carry audio and IMO it would be worth the few extra bills to get the setup that will do audio).

This will also be digital, and it's less than $20 delivered to your door and will work 100%. Seems like a no brainer to me, but to each his own.
 
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GadgetSlave

macrumors newbie
Oct 6, 2012
2
0
something is broken

My 2008 Core2Duo 2.4 MBP running OS 10.5.8 can drive my HD television using DVI > VGA adapter at 1920x1080 60p pixel perfectly.

My 2012 Quadcore i7 2.6 MBP running OS 10.8.2 can't display 1920x1080 60p using PNY Technologies Mini DisplayPort to VGA Adapter. Other resolutions work, but skew image and require TV to scale.

Same cable, same TV.

Is this a hardware limitation? System Preferences lists 1920x1080 as a resolution, it just doesn't work. Is the PNY adapter at fault?

My television sadly overscans all inputs except the PC VGA input. NO - I CAN'T USE HDMI. NO - I CAN'T USE DVI. NO - I WILL NOT USE SOME HACK THE UNDERSCANS THE VIDEO SIGNAL. NO - THERE IS NO TV SETTING THAT ELIMINATES THE OVERSCANNING.

Update-
Further testing indicates 2012 i7 MBP needs a better/shorter cable. 2008 MBP has no problems with 25' premium 15 wire (no missing connections - verified with mulitmeter) VGA cable. 2012 MBP will correctly output VGA through PNY adapter to 1920x1200 or 1920x1080, but only if I use standard 3' cable.
 
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