Our phillips tv 100hz digital scan 29pt9418/79 won't power up

a power surge can do alot of damage but does your model have a fused plug? as would check this. if you have changed the power board for a know working one then the main av board has gone this is the board that tells the power board to turn on.

Most likely standby is as powered down as it will get. There is some power used by TV sets when they are off, to maintain settings and channel memory, but this is very little power. You could put it on a power strip with a switch and turn off the power when you are not using it, but it's likely you will have to set it back up and scan the channels each time you turn it on.

These blinks [flashes] are fault indication (Error Codes). From the number of blinks occur at one time switch ON, you can get an idea about the faulty circuit stage inside it. This will make repair easy. These are called blinking codes. Make sure about the exact number of blinking of the standby/power LED, by switching On & OFF the set, for at least two times. Count it carefully. If you wish to get some details, check the site linked here. It has details about blinking codes, and fault locating procedure, to many popular brand TVs and other devices. Viewing it in "Mosaic" or "Magazine" will make surf easy.
http://electronicshelponline.blogspot.com/
Blinking codes details to many popular brand TVs are given. Surf the site with patience.

Check its main digital board for fault. Replace it if needy.

Good day!!!

if you have power problem without blinking lights or standby lights (red) the possible problem is power supply board..However if the TV have blinking or standby light but won't turn ON..there are multiple cause of that and need further troubleshooting..

I had the same problem a little while after the digital change over, channels were all lost struggled to get the set up menu up but when i did i retune the channels as soon as you turn the tele off there lost again. but it works if you leave the tele on standby. 2 people have told me it's the battery in the tele itself.

thesupply is not responding
take your tv for repair
let them check power supply
semi conductors, transistors, zener diodes, an dfuse resistors, also check the switch contact,
and fuse,

Sounds like a fault in the remote receive circuit or power supply. ambient electrical noise is getting into the circuit somehere. As it is not a new TV, I would suspect power supply capacitors, as they dry out with heat and age. Probably best to take it to a repair shop that gives free estimates/quotes, as there may be more on its way out and this is the first symptom.

Green flashing 3 times = digital DC - DC converter fault
Red flashing 3 times = scan circuit fault

Right i had this same problem for ages! i cannot explain why but when i uplugged my DVD player (which was flashing its light at the same time as the tv for some reason) the TV has worked fine.