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Louie, Technician
Category: TV
Satisfied Customers: 12437
Experience:  25+ yrs. experience in the field and 5+ yrs. online, down to component level.
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I have the Panasonic TH-42PZ80U in my office. This monitor

Customer Question

I have the Panasonic TH-42PZ80U in my office. This monitor is used as a video monitor (for editing). Today when I came in, I reached for the remote and turned it on. The read light comes on and stays lit...and the display seems to be on (slightly brightens) but there is no picture...and no menus will activate. If I let the TV sit for a while, I notice the power will cycle (could be the auto-off feature?). Any thoughts? FYI - Though not a TV repair guy, I was a technician for 20 years and very comfortable troubleshooting, soldering, etc.
Submitted: 1 year ago.
Category: TV
Expert:  Louie replied 1 year ago.

Hi and welcome to JustAnswer,

Thank you for the question and your patience. Should you still need assistance for information purposes only...

Initially, it would appear to possibly be a main board issue as the power supply seems to be working and the panel is priming. Proposed preliminary tries (if have not been done):

  • • cautiously enter Service Mode, please click HERE;
  • • carefully determine fault code / SOS history HERE.

The idea is to allow the built-in diagnostics to track potential suspect(s) / circuit failure.

A friendly reminder: most Service Mode settings are critical. An unnecessary/wrongful configuration change may and would render the Panasonic TH-42PZ80U completely inoperable.

Customer: replied 1 year ago.
Hi Louie,Thanks for the suggestions. I powered the unit and tried entering the Service Mode but was not able to get the menu to come up. However, because we are a video production company with several editing suites, I figured I'd try it on one of the other 3 TVs which are working fine (same model) and here's what I found. When powered on, if I press the volume button on the unit while toggling the info button (on the remote) 3 times quickly, the only thing that happens is the volume menu shows on the screen and the volume lowers. Next I thought...well, maybe the power needs to be "off". So I tried again, and got no menu.One additional thing I am noticing (on the bad TV) is that I have to hold the power button to turn the unit off...and even then, within seconds the unit seems to power itself back on again...and ever few minutes, that power cycles again and again. Thoughts?Thanks again.
Expert:  Louie replied 1 year ago.

Hi again Chris,

Surprised that the Service Mode did not work as that is as prescribed by the Service Manual for this model. Similarly, am surprised that there is no blinking LED that would also serve as an error indicator.

With this in mind, then 2 course of action; a lengthy check of present/missing voltages at each board or replacement of a likely failed board. The latter would serve then as both an attempt of a fix and as a test by process of elimination.

Please post back how you would want to approach this and/or should additional information be needed.

Customer: replied 1 year ago.
Thanks Louie, I will now be out of the office until Monday (4th).I'm guessing it must be the main board or some sort of Power Supply issue. It is starting to sound like it may be best for us to give up on the repair and replace the I will only have so much time to troubleshoot on my end.Thanks again and Happy New Year!Chris
Expert:  Louie replied 1 year ago.

I realize that the above information may perhaps be not what was expected. Unfortunately, there is no quick-n-easy fix and neither is there a workaround; sorry for having to be the bearer of bad news.