Hitachi tv will not turn on.

It's normal; if the set do not show a screen at this time. The red light indicates that the set is in standby mode, and it will off, when you hit the standby button again, and the scree will get live.
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Probably you should just disable the Standby feature, though it also depends on why it's in Standby. On some TVs, it's when it's been left on and idle for a certain period of time- basically the TV will turn itself off, or go into a lower powered state. It's possible it will not come out of it because the TV could be overheated, and needs time to go back to normal. Without know the specifics as to why the Standby happens I couldn't say, and it's also hard to say what the issue is with it coming out of it.

Go into the TV Menu and find Power Options. Set Power to Normal, or Quick Start (or whatever Hitachi calls it). If this is separate from the Standby Options, then disable the Standby option on its own.

Power board is dead.

First do you see a light indicating that the TV has power? There are two power buttons on the TV (the main power and the regular power button). The red standby light will light up when the main power switch is on. This indicator is just to the left of the remote I/R sensor. You can find the main switch on the bottom front of the tv (it is under the tv forward of the stand). Turn on the Main power if it is not on. Then try the power button on the control panel of the TV again.

Does the standby light change color or blink? (Red is standby, orange is power savings (no signal), blue is on.) If the main switch is on and the standby light doesn't come on, the TV has a problem at the power supply. Try unplugging the unit for a bit (at least 30 seconds) and then plugging it back in. This will reset the internal circuitry. If you see a blinking light, then the TV is reporting a self-test failure. I do not know the codes for this model Hitachi Plasma TV.

The manual for the Hitachi P50H401 TV is available from Retrevo: http://www.retrevo.com/support/Hitachi-P50H401-TVs-manual/id/1233ci869/t/2/ . You will need to enter a code to access the pdf.

I'm assuming you don't have one of the special versions that were intended for large audiences that were only controlled by remote (no control keys on the front of the TV). Remotes.com has the original remote or a substitute remote if you need it. See http://www.remotes.com/remotes/servlet/rs?a=gmi&uuid=13104063628240&smodel=P50H401&brand_pn=HITACHI_P50H401 .

I hope this helps.

Cindy Wells

unplug the unit for a while like one hour or so.

it is the power board in the tv hase some bad capasators in it but can cost some money to fix if unsher how to do it on your own if you live in central new york i do have my own shop and im cheep but i can not warenty any thing but i can help 315-280-0508 storm electronics ask for corey

The mainboard needs to be replaced

There are lights on the board about 8 you should look at which comes on and which stay on this by hitachi standards tells you what is wrong. Most of the time its convergence amps bad.