Raspberry Pi Forums

Hello,

I used a 1A USB to mini USB cable and my pi worked somewhat fine, once every 1 minutes the screen will go black for half a second.

so I decided to buy a normal mini-USB 2A 5V cable (searched in ebay "charger rasberry pi"). But when I connect it to the pi the screen goes black. (usually the screen shows check signal cable when nothing is connected). the pi itself seems to work but not the screen.

why is this happening?

thank you for your help

your HDMI lead may be a bit marginal
try another one
or see HDMI boost options
and the power lead you need is
USB to micro USB not mini
make sure it is of decent quality - i.e. not thin and long

RaTTuS wrote:your HDMI lead may be a bit marginal
try another one
or see HDMI boost options
and the power lead you need is
USB to micro USB not mini
make sure it is of decent quality - i.e. not thin and long

thank you for the quick answer.

Sorry I meant micro. I didn't understand your answer exactly. the quality 2A did not make the screen to work, the 1 A USB to micro usb did.

what is HDMI boost options? is it in the pi configuration or the screen?

Try a different HDMi cable would be my first step if screen issue

Regards HDMi options see http://elinux.org/RPiconfig

where you using the same USB lead to power the RPI?
not all USB PSU's are what they claim to be

RaTTuS wrote:where you using the same USB lead to power the RPI?
not all USB PSU's are what they claim to be

I use 2 Different cables.

one is a normal wall to micro USB cable which say 5V 2A which DOESNT work at all
picture: http://www.handy-foto-pc.de/pics/akkus/rlmicro2a.jpg

the second one is a Wall to USB plugged to USB to MicroUSB cable which works almost ok.
picture: http://img.tvc-mall.com/uploads/details/I5-753E-1.jpg

do you have a test meter ?

RaTTuS wrote:do you have a test meter ?

unfortunately not, I bought one on eBay and it is on the way...

could it be a configuration problem or do you think this is a cable problem?

Did you try another HDMi Cable ??

fruitoftheloom wrote:Did you try another HDMi Cable ??

no, have only this cable

Stick with the PSU that works best ,

can you upload a video of what happens

can you post your make and model of the display

RaTTuS wrote:Stick with the PSU that works best ,

can you upload a video of what happens

can you post your make and model of the display

when I stick the 1A it works normally, only every minute or so, the screen goes black for half a second and goes back to normal. I can do all normally, go on the internet and stuff.

when I stick the 2A the "no signal" is gone and in stead you get a black screen (one time i managed to get a really bad flickering image with bad proportions).

my screen is Flatron W2343T from LG

Does it make sense that the 1A works and the 2A not? I bought simply googeled 2A charger for pi and bought this one from ebay.

RaTTuS wrote:do you have a test meter ?

Hi, My testmeter arrived today, the 1 amper cable supply 4.85. the 2 amper 5V.

and these are tested on TP1 TP2 ?
sounds more like the HDMI lead is bad
try a
config_hdmi_boost=4
or bigger in the /boot/config file

RaTTuS wrote:and these are tested on TP1 TP2 ?
sounds more like the HDMI lead is bad
try a
config_hdmi_boost=4
or bigger in the /boot/config file

yes TP1, TP2. I tried a different cable but same result.

the config_hdmi_boost=4 were the default configurations.

i read the increasing the config_hdmi_boost could be risky, what is the maximum number I should try?

http://elinux.org/R-Pi_Troubleshooting
go up to 7 [or more but ....]
Another HDMI lead may be the answer
where in the world are you?

RaTTuS wrote:http://elinux.org/R-Pi_Troubleshooting
go up to 7 [or more but ....]
Another HDMI lead may be the answer
where in the world are you?

I am from Germany, I tried 2 HDMI Cables. I also have a DVID connector.

I still didn't understand how come the 1A 4.85 V works better then the 2A 5V. could my pi be defected?

RaTTuS wrote:http://elinux.org/R-Pi_Troubleshooting
go up to 7 [or more but ....]
Another HDMI lead may be the answer
where in the world are you?

I just read this in the link you gave me:

"Note that various adapters, such as HDMI-to-DVI, can also cause power loss and therefore require high values of config_hdmi_boost even with short cables."

I will try it at home and update

I have to say I don't know either ...

1A is way more than most Pis will ever use. The Pi B will use typically use 400mA and normal wired peripherals will use maybe another 200 mA (My cheapo Keyboard and mouse use about 15mA each and a cheapo Wifi adaptor about 50-70 mA). 4.8V is a pretty safe minimum voltage, one of mine is perfectly stable at 4.65 volts. I've always had my doubts you could reliably get 2A through a micro USB connector with a respectable voltage drop. Come stuff out there is VERY conservatively rated if Micro USB takes 2 amps....