Sensitive Screen whilst charging FIX

[Guest wilx01]

I have managed to fix the sensitive screen issue on charging..... I am now using an alternative REGULATED power supply, which shows what I feared, that the power supply supplied has poor voltage regulation/ smoothing. I now have no multiple key presses on typing, and screen response is back to normal.

I am now using a Uniross UNI 1200R power supply unit ( The R stands for Regulated). You need to check that the power supply is "REGULATED" or it may not work. This was purchased many years ago from Argos I think, and comes with a multitude of plugs, and various voltage settings between 1.5 and 12 volts. The unit supplies 1.2 A (you need a unit that will supply at least 1 amp) and I have it set to 12 Volts

I can't find any anywhere now, except this one on ebay, as you can see.... it is far from portable as you can see.

http://cgi.ebay.co.uk/Uniross-1200R-Mains-...623344049302232

I am sure there will be others around for sale elsewhere

Maybe a smoothing capacitor inside the shipped model may work if someone is feeling adventurous? (If its smoothing that is the problem rather than the regulation?)

Edited December 31, 2010 by wilx01

[Guest goldenbolux]

I have never had any of the supersensitive screen issues while charging

i think this is due to the fact that my power supply blew up when i first plugged it in

i got a replacement from rs to tide me over till i was shipped a new one from currys

i have just tried the official one from currys and have to admit that screen does not behave like it does with the one from rs

[Guest mattlokes]

I have never had any of the supersensitive screen issues while charging

i think this is due to the fact that my power supply blew up when i first plugged it in

i got a replacement from rs to tide me over till i was shipped a new one from currys

i have just tried the official one from currys and have to admit that screen does not behave like it does with the one from rs

which charger from RS did you get? :(

Matt

[Guest goldenbolux]

Im not sure as i am not at work

I think i just searched 12 volt 1 amp ithink

There is 2 with the interchangeable ends

I just use one of them and it seems fine

[Guest goldenbolux]

I think one of the oness i got was 512-6848

Im sure thats the one i have been using

[Guest wilx01]

I have never had any of the supersensitive screen issues while charging

i think this is due to the fact that my power supply blew up when i first plugged it in

i got a replacement from rs to tide me over till i was shipped a new one from currys

i have just tried the official one from currys and have to admit that screen does not behave like it does with the one from rs

512-6848 does not have a price on the link I've tried.... how much was it?

Edited December 31, 2010 by wilx01

[Guest terminaljunkie]

http://www.buythis.co.uk/open_product.asp?...;source=Froogle

Any good?

[Guest wilx01]

http://www.buythis.co.uk/open_product.asp?...;source=Froogle

Any good?

Looks. OK spec wise but what size plug does it have?

[Guest ColonelK]

I have noticed exactly the same issues with the touchscreen when charging. However, I do not believe that this is due to poor voltage regulation by the original power supply as mentioned above.

Instead, I think the explanation is that the original Vega power supply (APD WA-12112R) is very likely to be a Switch Mode power supply. These supplies are almost ubiquitous, because they offer much higher efficiency, lower running temperatures, smaller size etc. when compared to Linear Regulated Supplies. However, they do produce more EMI (Electromagnetic Interference) and, to avoid this, often include capacitative filters at their output side which can result in the common output terminal floating at half mains voltage (!) This can often actually be felt as a "tingling" sensation when touching the casing of a device (such as the metal trim on my Dell Laptop for example..)

This will be current limited by a series resistor inside the power supply for safety - so although the output floats at what is nominally quite a high voltage, it shouldn't be able to deliver enough current to injure the user. However, I would speculate that it might well be delivering enough current to interfere with the capacitative touch screen.

This would also explain why some people have found that connecting the Vega to a PC via USB can help reduce the problem, since that would electrically earth the Vega through the PC.

If you are considering replacing the power supply, you should certainly use a Regulated Power Supply. However, there are at least two different types: Linear Regulated and Switch Mode. Using a Linear Regulated supply may help to eliminate the problem (although it may also run hot), whereas another replacement Switch Mode supply might possibly have the same issue.

Edited January 5, 2011 by ColonelK

[Guest gingercat]

However, they do produce more EMI (Electromagnetic Interference) and, to avoid this, often include capacitative filters at their output side which can result in the common output terminal floating at half mains voltage (!) This can often actually be felt as a "tingling" sensation when touching the casing of a device (such as the metal trim on my Dell Laptop for example..)

Aha! That explains that odd sensation I sometimes get with various devices! Thanks.

[Guest ColonelK]

Aha! That explains that odd sensation I sometimes get with various devices! Thanks.

I decided to test this in practice (see below). Needless to say, please don't try this at home. The digital multimeter was set on AC 200V range.

Anyway, please don't be alarmed by the picture, as it would only be able to supply a tiny current to earth, and this happens with pretty much all consumer switch mode power supplies. I'm confident that the Vega power supply is perfectly safe and meets all the relevant safety standards.

I guess it could be one possible explanation for the flaky touch-screen when charging though.

Edited January 5, 2011 by ColonelK

[Guest Touch Graphite]

However, they do produce more EMI (Electromagnetic Interference) and, to avoid this, often include capacitative filters at their output side which can result in the common output terminal floating at half mains voltage (!) This can often actually be felt as a "tingling" sensation when touching the casing of a device (such as the metal trim on my Dell Laptop for example..)

WOAH! And there was me thinking I was alone in this world, I've been trying to prove to my workmates that all Dell laptops are well dodgy by rubbing the speaker covers either side of the keyboard when its charging.

They claimed they felt nothing. I thought I was developing some secret superpower like whatshisface off Fantastic 4.

[Guest Touch Graphite]

I decided to test this in practice (see below). Needless to say, please don't try this at home. The digital multimeter was set on AC 200V range.

Anyway, please don't be alarmed by the picture, as it would only be able to supply a tiny current to earth, and this happens with pretty much all consumer switch mode power supplies. I'm confident that the Vega power supply is perfectly safe and meets all the relevant safety standards.

I guess it could be one possible explanation for the flaky touch-screen when charging though.

Wait a second, your claiming your getting 90V AC to earth off the negative output of a Vega PSU!?

Surely not.

BTW, Dont get confused between regulated outputs which maintain the voltage level at 12v DC etc.

And outputs which the negative are tied to 0V, not to get a imbalance between the negative level and the positive level.

i.e a 12V DC Output could mean the positive pin reading 15V and the negative pin reading 3V, resulting in a 12V DC Potiential Difference.

The only way would be to read it to Earth like ColonelK here.

[Guest ColonelK]

Wait a second, your claiming your getting 90V AC to earth off the negative output of a Vega PSU!?

Surely not.

Large potential difference to earth, but a tiny current, therefore harmless :unsure: More detail here if anyone is curious:

Switch Mode Power Supplies

(see comparison table against linear regulated supplies)

The same power supply reads 12.37V DC between the terminals off load (probably not much different under load). Out of curiosity I checked the Vega power supply output with an Oscilloscope and mine looks as smooth as butter, so I don't think it's noise on the DC output.

It's a minor irritation really, but I might try a different Power Supply this weekend to see if it improves matters.

[Guest ColonelK]

WOAH! And there was me thinking I was alone in this world, I've been trying to prove to my workmates that all Dell laptops are well dodgy by rubbing the speaker covers either side of the keyboard when its charging.

They claimed they felt nothing. I thought I was developing some secret superpower like whatshisface off Fantastic 4.

Funny :unsure:

It's not just Dell apparently (Shocking Powerbook) - although I'm writing this on a MacBook Pro without any ill effects, so maybe they fixed it B)

[Guest Squire_Au]

The "floating at half mains voltage" problem is pretty normal for non-earthed devices. The mains input filter forms a capacative voltage divider between active and neutral, resulting in anything connected to the centre point floating at half mains - in Australia, about 120V. The capacitors have very high resistance at mains frequencies, resulting in extremely low current at the centre point, in this case the negative terminal of the power supply. But it's there, and makes you jump if you're not expecting it.

A worse situation occurs with long mains leads and the earth open circuit at the power point... the case of the device can give you a serious bite. I got one while working on two adjacent pinball machines. One was properly earthed at the power point, one wasn't. When I touched the metal parts of both machines, I got a fairly nasty 120V shock.

Having said all that... it's most likely high frequency noise in the power supply output that causes the touch screen problems. Better filtering in the supply should cure it. Or using a standard analogue power supply (a plugpack with a transformer, not a switchmode). Just make sure it is 12v... any higher will severely shorten the life of the battery.

I get a nasty buzz through my headphones when my DreamBook ePad P10 (Aussie version of the Vega) is playing music and connected to the charger. It's way worse if I connect the charger to my inverter that's attached to a big 12V battery, for when I'm camping. Good thing my ePad had long battery life.

Has anyone found a good car charger for the Vega? I have found a lot on Ebay, but not sure whether the plugs will fit. It's hard to get the exact dimensions of the plug from an Ebay seller, especially one in Hong Kong.