HPa6600f has long beep when powered on. After 15 seconds goes off for 5 seconds and goes back on. Nothing appears on screen. Have powered off and removed both Ram sticks one at a time but no change. I suppose it's CPU or motherboard but not sure or how to check.

try an external monitor.

1.Check the device's battery level for at least two bars of strength.
2.If the battery level is low, charge the battery.
3.If the issue is not resolved, remove the back cover.
4.Remove the battery.
5.Wait 10 seconds.
6.Press and hold the W key.
7.While pressing down the W key, re-insert the battery.
•The device restarts and after approximately 15 seconds, the 'Recovery' screen appears
•Release the power button but *continue holding the home button*, for another 30 seconds.
Step
Thanks

That happens when you change tv.
Unlpug it and wait for 30 seconds.
Plug it back. The red red light that indicates that the ps3 is off should be on.
The light must be red(turned off)
Now do this:

PRESS and HOLD the power button for 5-6 seconds untill you hear the second beep

There you go
check here if this didn't work
http://www.portfolioofpb.com/blog/update-ps3-blank-screen-switch-inputs-hdmi-to-composite-to-hdmi
Please rate if this solved your problem

If not solved yet, make sure the fan is spinning on the heat sink on the processor. If it is, then if you have a video card installed, make sure that fan is spinning. These are 2 pieces of hardware that will cause the beeping and shut down.

this is often related to a possible motherboard problem. Try these steps: turn it off, remove the battery, and AC adapter, then press and hold the power button for about 5 to 10 seconds. Once done, reconnect at least the adapter , turn on the laptop and as soon as the Dell logo shows up, tap F2 a few times to enter System Setup (BIOS screen). From there, go to the Maintenance category, and select Load Defaults, press Enter. Press ESC, then select Save/Exit, restart the computer and see how it goes.

beeping from power cord

Ok, you need to hold the power button down for 5 seconds until it beeps once, this will revert back to standard definition.

Hope this helps

Put your PS3 in Standby Mode.
The first thing your going to want to know is your model number. It can be found on the back panel of the PS3 on the serial number label, and it will begin with CECH. Example - Serial: XXXXXXXXXXXX-CECHXXX -
For models: CECHA01, BO1, E01, E01MG, G01, H01, H01MG, K01, LO1, AND P01, it will have a power switch on the back. Flip it off then back on and you will have a solid red indicator light on the front.
For models: CECH-2001A and 2001B, press the power button on the front until the indicator light turns red. If all else fails unplug the power cord and plug it back in.
Time to enter Safe Mode.
Press and hold your finger over the power button on the front until you hear three beeps and the indicator light goes back to red. Then release the button. (The second you touch it you will hear a beep, that's the first beep. Five seconds later a second beep, another five seconds the third and final beep will sound then the indicator light will return to red.)
Press and hold your finger over the power button again until you hear a quick double beep. The release the button. (The second you touch it you will hear a beep, that's the first beep. Five seconds later a second beep, another five seconds you will hear the double beep.)
Connect controller to PS3 screen. You will then see this screen. "Connect the controller with the USB cable, then press the PS button".
Connect the USB cable to the USB port on the front of your PS3 and the top of your game controller, (between the left and right bumpers). Then Press the PS button in the center of the controller.
Safe Mode options screen. You will then see this screen.
-REMINDER: -BY DOING THE FOLLOWING ALL OF YOUR DATA ON YOUR PS3 WILL BE LOST, YOUR ONLINE STATS ARE ON THE NETWORK SO YOU WILL GET THAT STUFF BACK, INCLUDING GAMES AND ADDONS YOU BOUGHT FROM THE PSN.-
Select option number 5. (Restore PS3 System). Then select yes to perform step.
You will then see a screen. "The hard disk's file system is corrupt and will be restored."
The PS3 will then restart. You will see many different languages, all that is is saying is, "Connect the controller with the USB cable, then press the PS button". Press the PS button and set your settings when it finishes it will start up and its fixed!

try rebuilding the database and the file system in recovery consol

to get to the recovery consol press and hold the power button when ps3 is in standby mode(red light) till you hear a double beep. sometimes the ps3 does a beep then another beep and goes back into standby thsi is fine just release the power and quikly press and hold it again till you get double beep.

like on my 80g system it goes like this

ps3 standby...press hold power.......beep .........beep........stanby again....release and hold power again.......beep .........double beep...release power now you should be in recovery menu.

You may have messed up the Screen-Settings, to solve this try this.

Step 1: Turn off the PLAYSTATION 3 by holding the Power button on the front of the unit till the Power light is red.

Step 2:

1. Touch and hold the Power button, you will hear the first beep, meaning the PLAYSTATION 3 is powering on.
2. Continue to hold the Power button and after about 5 seconds, you will hear a second beep, indicating the video reset.
3. Continue to hold the Power button and after about another 5 seconds you will hear a third beep and the system will power off (Power light is red).

Step 3:

1. Touch and hold the Power button, you will hear the first beep, again for the PLAYSTATION 3 to power on.
2. Continue to hold the Power button and after about 5 seconds, you will hear a second beep for video reset.
   
3. Continue to hold the Power button and after about another 5 seconds you will hear a quick double beep. At that point release the Power button. If you succeeded in activating Safe Mode, you will see a message on the screen saying, "Connect the controller using a USB cable and then press the PS button."
4. Connect a USB cable to the controller and the PLAYSTATION 3 and press the PS button to enter Safe Mode.
5. Then you will see the Safe Mode menu.

Step 4: We recommending performing the safe mode options in the following order until one of the options works for you. If one of the options work, do not continue onto the other options.

1. Restore Default Settings
2. Restore File System
3. Rebuild Database
4. Restore PS3 System (This will wipe your harddrive, so remember to backup savegames.)