Service menu in flat-panel TVs; "high voltage" on flat panels?

[Jeffhs]

Are there on-screen service menus in today's flat-panel televisions, accessed by keystrokes on the remote? I'm not interested in altering any service-control settings on mine (rebadged Sylvania 19" FP); I am just curious, after reading the posts dealing with the OS service menus (and the methods used to access them) on 1990s-era CRT sets. .... Which reminds me. Is there an OS service menu on the Zenith Sentry 2s? Again, I am curious since I have such a set, which does not seem to have variable adjustments for height, width, centering, et al.

Again, I am definitely not interested in changing (and will not change) any service control settings on either my FP set or my Sentry 2; I am simply curious as to whether the sets have on-screen menus for service adjustments since, as I mentioned, the Zenith does not seem to have variable potentiometer controls for height, width, linearity, etc. (unless they are hidden behind the set's back cover, which I have not removed in the 16 years I've had the set); I do not see any such controls on the FP either. Are FP TVs so stable that they do not need manual adjustments for picture size, height, width, etc., even to compensate for component aging, or do the components in FPs not age as quickly as those in CRT sets, due to lower voltages in the former? For that matter, are there any really high voltages (in the kV range) anywhere in today's FP sets? I would think not, since LCD displays typically do not need thousands of volts to operate properly.


Thanks in advance.

[Eric H]

Yes, there are service menus in most if not all FP sets and CRTsets.

My 1990 Sony XBR had a service menu that was accessed by holding down a hidden button while powering the set on. Everything from Gray Scale to Pincushion was set though the menu.

My Panasonic Plasma has one and so does the Sony LCD projector, accessed by pressing key buttons on the remote and then powering up, both of them have the ability to see how many hours the set has been on, and also the number of power ups, useful if you are thinking about buying a used one.

Even a cheap little 2002 Samsung 14" set has a service menu, although limited.

The danger is that you could adjust something like the Horiz frequency so far off you won't be able to see the picture to undo the mistake. Fortunately most of them require a step to "Save" the settings before you exit, if you just pull the plug it goes back the way it was.

[ChrisW6ATV]

Jeff-

There are no voltages near a kilovolt in an LCD TV, but the ones with fluorescent backlights (as opposed to the LED-backlit ones) will have a few hundred volts (if I remember right) for the bulbs, coming from an inverter circuit. I do not know the voltages used in plasma sets, but they are likely higher.

Flat-panel TV sets do not need traditional height/width/linearity controls, because they are digital internally; that is, every pixel on the screen has a known position and a circuit output assigned to it directly. The nearest thing to geometry adjustments would be for scaling analog input signals to the panel's display area, and even that can be done with fixed mathematical counting circuits derived from a crystal oscillator.

[Gunslinger]

I think Zeniths were acessed by the remote. Press 9876enter . Not sure; too many years have gone by.

[mbates14]

not sure about CCFL voltages, they vary. some are a few hundred volts, some of them are a kilovolt. Depends.

But plasmas are more dangerous because they use 200v sustain voltages to run the panel, but the sustain output amplifiers can produce Volts Peak to Peak swings that are greater than few hundred volts at high enough frequencies to cause RF burns.