VGA Voltages?

snadge

snadge

snadge

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11 Oct 2010
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after a Acer P193w monitor failing recently (shortly after installing a nVidia GT-220 I got from a friend) and the temporary replacement doing something similar to what the old one done the other night (but this one came out of its 'boot loop' that lasted a few seconds) I decided to test the voltage coming off the pins...

I was told to measure pins:
6 (GND) & 1
7 (GND) & 2
8 (GND) & 3

and that I should be getting 0.7v off that - thing is I got NO READINGS at all?? I had Multi-Meter set correctly on 20v setting which allows readings of 000.00v -/+ - I kept my GND on pin 6 and tried some of the other pins and I got 4.9v readings on pins 9, 12 and 15 - but to get the 4.9v reading on pin 9 I had to move the GND to pin 4..? (i think thats correct)

I can find little information about the voltages on all pins except that 1,2 and 3 are supposed to be 0.6-0.8v

can anyone help determine if this card is healthy or not?

Iam going to retest with my HD2500 iGPU later

just I have a replacement monitor coming soon and I dont want this GPU breaking all my monitors lol

thanks
 
Is your meter set for an AC signal or a DC signal. The signal is a 0.7v peak to peak analogue signal and it moves pretty fast (well actually it is very fast) so you may not see much with a meter. Try setting your meter to AC and perhaps an order of magnitude lower than you have at present. The meter should be able to see at least some AC signal and give you an approximation.

Also if the VGA is outputting a black signal the voltages will be low to non-existant anyway.

Some of the pins will be 5v but without researching about VGA outputs and stuff I couldn't tell you if our results are as expected.
 
thanks for your reply :)

I believe it was on DC (straight line with dots under it?) - but I did try the AC one (wavy line) too and nothing?

its a MASTECH M-830B multimeter

I tried it on (DC) 600v, 200v, 20v, 200m and 2000m - and also 200v AC and 600v AC

my desktop is black but has lots of icons on, i know it was displaying that during one test... perhaps I should have a full screen video running?
 
....continued from above post...

I had a full screen video running and only reading i could get on the RGB pins was 01.5 on pin 1 and 01.4 on pins 2 & 3 - this was with the MM on 200m mode (200mV i presume?)

so is this measuring 1.4v ?? which is way too high is it not? - if so then why cant it detect that on 20V mode which is sensitive to 2 decimal places (1.00v)

also when I unplug the monitor you can hear windows making the ding/dong noise informing you of something being unplugged...so maybe it cuts off?

thanks
 
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Your meter isn't able to read small signal AC signals such as the VGA signal uses. DC readings are useless on AC signals.

Ideally you'd have a meter that can display AC to low voltages like your meter can do DC.
 
so its AC voltages that are on there?

strange I get 5v readings using DC on some pins?

I can get .1 volt readings on my MM I think as it displays 00.0 when set on 200v
is it 0.7v AC or 0.7mV AC on these 3 pins?

EDIT: I done it again with setting on 200v AC and it does display 0.1v as ive seen it do it as its flicking up through numbers, no result again and the 5v readings I got before say 10v on AC?

thanks
 
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AC for the RGB yes. DC on some pins I guess.

Check the pinout and cross reference the names for what they are and do.

If the VGA is sending damaging transients you will not be able to detect with a meter anyway. You'd probably need a oscilloscope and maybe a peak detector.
 
Tealc said:
If the VGA is sending damaging transients you will not be able to detect with a meter anyway. You'd probably need a oscilloscope and maybe a peak detector.
Click to expand...

...which is just wayyyy out of my league lol...

oh well thanks for your help I really appreciate it :)
 
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