Raspberry Pi Model B HDMI issue

That troubleshooting should help you if you follow it all. What bits did you do?

Is your RPi running if you access using SSH for a terminal? Can you get it to output via composite video?

How are you editing config.txt? Can you post a copy of the file for us to see?

My own experience is that if the TV/monitor is modern, known to be working and has the right input selected then the most common cause is the HDMI cable not plugging into the RPi properly - this is a frequent problem if the RPi is in a case, as many cases tend to obstruct the HDMI socket just enough to stop it connecting (but you think it's plugged in OK). If RPi doesn't find an HDMI monitor during boot, it stops looking thereafter so pushing the plug later will not work. If in any doubt, take the RPi out of the case while you test

Hi, i took the RPi out of the case and booted it up. At first it looked like it was working but then it started to flicker constantly.
Check this video: https://www.dropbox.com/sh/15pn6wi1q2nnd4y/AACSHsizY7tpYOoKEpnerK6Pa?dl=0

I was able to start the (default) OS installation, but the screen just went black after a while; with a message displaying "Check Video Cable". (screenshot)
Now when i turn it on, i only get the message "Check Video Cable", the flickering stopped.

This is what i have for my config file:
config_hdmi_boost=4
hdmi_force_hotplug=1
hdmi_safe=1

Did you check +5V voltage level between TP1 and TP2?  I'm the guy who added the low voltage cause to the RasPi Troubleshooting Wiki.  When I was first powering my Model B my power supply had an iffy connection, and whenever the voltage dropped below a certain level (I'd have to look it up) my monitor would first show random green dots and then blank out totally.  It would depend on what RasPi was doing.  Sometimes it worked fine until I did something compute-intensive like compiling, and then return to normal after the compiling ended.  The +5V voltage wasn't low enough to affect anything else.

Nowadays I back-power RasPi from a Motorola Atrix Lapdock using a very short USB cable, so I get nearly 5V at TP1-TP2.

There is also this blog on the E14 web site on the same ting John is describing, more focused on the cables (USB) used when providing power Raspberry PI:- USB power cables, crashing and other problems

Also I note from your screen view, that the screen may not be full HDMI, and not compatible with the output from the PI, what is the spec of the screen ? is it 720P or SD, Or something else

First, I can't see your video ('Page not found' error from Dropbox), so I'm a bit in the dark; others obviously have seen it though!

Second, I'm going to ignore the 'check the 5v power' dialogue - I'm not saying it is wrong, just it is a completely different possiblity and I am not the expert!

If your screen showed the OS selection dialogue, it tells us the conections are working. That will be a low resolution screen though, and maybe your monitor will not cope with higher or different resolutuions?

A point of HDMI is that during startup, the monitor tells the RPi what resolutions it can show, and RPi chooses the 'best' amongst these. When you add those lines into config.txt, RPi ignores that dialogue (that's what the 'hdmi_force_hotplug=1' does) and RPi chooses a low resolution instead (I think it's 1024x768 60 Hz). 'hdmi_safe=1' does something similar, but difference between the 2 commands is that 'hdmi_force_hotplug=1' doesn't even need a monitor plugged in at all - just forces it to send low resolution down the wire, ignoring whether there is any feedback.

So, what might be going on? Your monitor obviously works at some resolution or other. But it might not work at the default low resolutions (unusual, but possible). I would try the following with the physical setup that you know can display something (ie, RPi uncased). Also, use a direct cable - no 3:1 HDMI switch box or similar.

1. Remove those lines from config.txt and see if it now works if the RPi can negotiate with the monitor.

2. If not, look up the monitor manual for a list of resolutions it is capable of. Need to know both the reolutions (eg 1024x768) and the refresh rate (eg 60 Hz). Or they may be specified TV-style (720i, 720p, 1080i, 1080p etc). If you post those lists here, we can look up some extra parameters to add into config.txt alongside hdmi_force_hotplug=1, to force the RPi into one of the acceptable modes.

We will get there!!

Hello,

I have a Pavilion 25xi monitor, it is fairly new and has a resolution of 1920 x 1080.

Here are some things i tried again:

- I removed the lines from the config.txt file, but then i get a "Check cable" dialog when booting the RPi.
- I added "hdmi_safe=1" to the config.txt file, i was able to see very low resolution output on the screen for a few seconds. But then the screen turns black and stays that way.

Some other commands which didn't work (tested them one by one):

framebuffer_width=1920
framebuffer_height=1080

hdmi_force_hotplug=1

config_hdmi_boost=4

Hope to hear from you soon!
Too bad i don't have another monitor to test it out.

If it is a modern HDMI monitor then you should not have to modify any of the config files after imaging the SD card, it just works

this is a video I produced setting up Raspbian

Raspberry PI Model B+ Quick Set-up (1/2 Hour Guide from unpack to GUI and WIFI)

btw, how are you modifying the config files ?, remote SSH, XWINDOW ?

n HP Pavilion 25xi is indeed modern and should cope perfectly if 'just plugged in' to an RPi via HDMI.
Here are lines to include in config.txt to force a couple of resolutions. I suspect these will not work any better than what you have tried already though. In which case, try the alternate possibilities of insufficient voltage suggested by others. (unplug everything from the Pi except the monitor and a keyboard ...), and measure the voltage between TP1 and TP2 after trying to boot. Or, if it boots with nothing else plugged in, then you've found the problem!

I have left in the comments to explain what the lines do and what you can try. This is straight from my own config.txt and modes 4 and 16 both work fine.
# uncomment if hdmi display is not detected and composite is being output
# eg if using 3 to 1. Defaults to low resolution unless uncomment rows below too
hdmi_force_hotplug=1

# uncomment to force a specific HDMI mode
# note these override choosing 'best' mode even if a monitor is detected
# (mode 16 will force 1080p 1920x1080, 60Hz, progressive)
# (mode 4 will force 1280x720, 60Hz, progressive)
hdmi_group=1
hdmi_mode=4

And the following is a longer list of possible resolutions - these are just the ones that my 1920x180 monitor can cope with..
HDMI_group=1 (CEA) has 15 modes:
           mode 1: 640x480 @ 60Hz 4:3, clock:25MHz progressive
           mode 2: 720x480 @ 60Hz 4:3, clock:27MHz progressive
           mode 3: 720x480 @ 60Hz 16:9, clock:27MHz progressive
           mode 4: 1280x720 @ 60Hz 16:9, clock:74MHz progressive
           mode 5: 1920x1080 @ 60Hz 16:9, clock:74MHz interlaced
           mode 6: 720x480 @ 60Hz 4:3, clock:27MHz x2 interlaced
           mode 7: 720x480 @ 60Hz 16:9, clock:27MHz x2 interlaced
  (prefer) mode 16: 1920x1080 @ 60Hz 16:9, clock:148MHz progressive
           mode 17: 720x576 @ 50Hz 4:3, clock:27MHz progressive
           mode 18: 720x576 @ 50Hz 16:9, clock:27MHz progressive
           mode 19: 1280x720 @ 50Hz 16:9, clock:74MHz progressive
           mode 20: 1920x1080 @ 50Hz 16:9, clock:74MHz interlaced
           mode 21: 720x576 @ 50Hz 4:3, clock:27MHz x2 interlaced
           mode 22: 720x576 @ 50Hz 16:9, clock:27MHz x2 interlaced
  (native) mode 31: 1920x1080 @ 50Hz 16:9, clock:148MHz progressive
HDMI_group=2 ( DMT) has 20 modes:
           mode 4: 640x480 @ 60Hz 4:3, clock:25MHz progressive
           mode 5: 640x480 @ 72Hz 4:3, clock:31MHz progressive
           mode 6: 640x480 @ 75Hz 4:3, clock:31MHz progressive
           mode 8: 800x600 @ 56Hz 4:3, clock:36MHz progressive
           mode 9: 800x600 @ 60Hz 4:3, clock:40MHz progressive
           mode 10: 800x600 @ 72Hz 4:3, clock:50MHz progressive
           mode 11: 800x600 @ 75Hz 4:3, clock:49MHz progressive
           mode 16: 1024x768 @ 60Hz 4:3, clock:65MHz progressive
           mode 17: 1024x768 @ 70Hz 4:3, clock:75MHz progressive
           mode 18: 1024x768 @ 75Hz 4:3, clock:78MHz progressive
           mode 21: 1152x864 @ 75Hz 4:3, clock:108MHz progressive
           mode 32: 1280x960 @ 60Hz 4:3, clock:108MHz progressive
           mode 35: 1280x1024 @ 60Hz 5:4, clock:108MHz progressive
           mode 36: 1280x1024 @ 75Hz 5:4, clock:135MHz progressive
           mode 39: 1360x768 @ 60Hz 16:9, clock:85MHz progressive
           mode 42: 1400x1050 @ 60Hz 4:3, clock:121MHz progressive
           mode 47: 1440x900 @ 60Hz 16:10, clock:106MHz progressive
           mode 48: 1440x900 @ 75Hz 16:10, clock:136MHz progressive
           mode 51: 1600x1200 @ 60Hz 4:3, clock:162MHz progressive
   mode 58: 1680x1050 @ 60Hz 16:10, clock:146MHz progressive

I still do not understand why you need to set any forced values to get it to work

I tried mine on a few different HDMI screens at home and everyone worked without adjustment

It will be interesting to see if it is something other than power related

if you have not read the blog articles Myself and others have provided, I suggest you do before spending too much time on other avenues of investigation