Raspberry Pi Forums

I recently received a raspberry pi 3 model B as a christmas gift, and so far everything has worked fine, except for one problem. I bought the pi in a canakit starter kit, which comes with a power supply, heat sinks, an HDMI cable, and a preloaded NOOBS card (along with the pi). I originally planned to use the pi on a small 15" polaroid tv that has been lying around unused fir some time, and has a VGA port in the back. In order to use the pi with this I also received an HDMI to via converter, which is a single cable with one end being the HDMI to plug into the pi, and the other end being the VGA to plug into the tv. When I started up my pi for the first time everything went smoothly, and I successfully set up Rasbian os on the pi. After a little bit of use however, I noticed that occasionally the screen would go blank for about 1-4 seconds, and then come back on. As time went on, this occurred more and more frequently, until the problem happened about once every 5 seconds. My first reaction was that our HDMI to VGA cable was faulty, so I tried using it on a separate television, this one having both HDMI and VGA ports. The raspberry pi worked just fine, and I experienced no blanking whatsoever. Next I tried the pi using the standard HDMI cable included in my kit, and once again everything worked fine. I returned to the old television and the blanking persisted. I did a little searching online, and decided that the problem might lie in the resolution being output by the pi, so I went into the config.txt file and tried making some changes, none of which worked. Since then, I have changed dozens of thing in that file, but the problem continued. What is strange is that when the raspberry pi is first started the problem is nonexistent, but after about 3-4 minutes it starts up again, and after around 7 minutes it is happening at a rapid pace. This makes me think that something is physically wrong with some aspect of the connection between the pi and the tv, but right now I really don't know what that could be. Please let me know if you have a solution to my problem, or if you believe that the monitor is faulty and needs to be replaced. Thank you for your help, and have a nice day.

Have you played with config_hdmi_boost in /boot/config.txt?

The RPi is apparently generating a steady HDMI video signal: you have proved that for yourself by testing with a display that has an HDMI input.

Maybe the problem is not the RPi but with the hdmi-vga conversion?

Can you independently test that convertor and its connection to the target VGA display by using some other source of an HDMI signal, maybe a 'set-top' tuner or a DVD player?

As far as changing the config_hdmi_boost settings I have tried doing that a little bit, but didnt really know what to do. Do you have any recommendations on what might work? Also I have tried connecting an Apple TV to the small tv using the hdmi to vga cable, but nothing showed up on the display because the Apple tv's resolution was to high.

Blatent plug : https://www.lo-tech.co.uk/product/rpi-vga-board-pcb/

Does the red power LED ever blink? You can try going to 7, the max suggested value. Higher values are possible (11?) at your own risk

So I tried that and it did not work. Is there a way to connect the pi to my tv through the auxiliary jack?

hef.1954 wrote:So I tried that and it did not work. Is there a way to connect the pi to my tv through the auxiliary jack?

RPis have a composite video output which can be connected to the AV input present on most TVs, often the yellow RCA phono socket. On a RPi3 that signal is one of the connections in the 3.5mm AV socket. You need a correctly wired cable. See viewtopic.php?f=91&t=83446, scroll down to item 5 and keep going down until you come to the diagrammatic representation of a 3.5 mm plug with the numbers 1 to 4 on the connection rings.

However, the resolution and picture quality you can obtain with composite video are very markedly inferior to HDMI. That is inherent in composite video, not a failing of the RPi.

Thinking bact to my first pi - I had an issue with the HDMI cable. I swapped ends and - wala! it worked! Turned out that the connector wasn't making good contact inside the the pi's HDMI socket. Someone else reported a problem with an HDMI -> VGA converter needing more power than the pi could deliver, so he performed a bit of "surgery" on the converter to provide 5V directly.

I just got one of those converters from Adafruit and so far, no problems with the video. Haven't tried it the audio yet.