panasonic tx-p42ut30b

[gobby009]

hi guys having a problem with this tv wont turn on.no standby light no clicking noises nothing. done some basic voltage checks on the power board as im an amatuer and theres nothing from top to bottom not one reading.any help would be appreciated.

[gobby009]

Re: panasonic tx-p42ut30b

just took the power supply off and seen discolouring like burning on the back could this be the cause?see picture

[R_J]

Re: panasonic tx-p42ut30b

Have you checked the fuse's? Do you have a/c at the white plug (lower left pic#3) Check that white ceramic resistor R104, (it is in the upper left near the 2 relays) it has 3 legs. it should measure 10 ohms across the 2 legas at the one end, it could be open.

don't worry about the discolored pc board it's just discolored from the heat of the parts in that area.

[gobby009]

Re: panasonic tx-p42ut30b

dont know how to check the fuses on the board maybe you could tell me and what setting the multimeter needs to be on to check them.i checked the ac voltage on the white plug and it reads 370 i then turned it to ohms if thats the right setting on my multimeter see picture and it reads 3.7 and kept tripping my eletric.

[diif]

Re: panasonic tx-p42ut30b

The only measurements to do with power applier are voltage checks. Everything else with the power off.
Put your meter into diode mode, measuring across a the fuse should show near 0v. You can also check it in ohms mode (resistance), it should read near 0ohms.

[gobby009]

Re: panasonic tx-p42ut30b

Have you checked the fuse's? Do you have a/c at the white plug (lower left pic#3) Check that white ceramic resistor R104, (it is in the upper left near the 2 relays) it has 3 legs. it should measure 10 ohms across the 2 legas at the one end, it could be open.

don't worry about the discolored pc board it's just discolored from the heat of the parts in that area.

checked the r104 and it reads 1 think i might have shorted it when i checked it with the leccy on.

the 5 fuses on the board the 2 pink line ones read 1 and the other three read 0.

would replacing these fuses and r104 resistor be worth doing.


what are the 2 fuses with the pink lines in the middle and where would i get them and the r104 resistor.

[Moreno83]

Re: panasonic tx-p42ut30b

Be carefull plz , you might get a shock or damage the tv even more.

Take a look at the powersupply. There is a white line in the middle that "cuts" the powerboard into 2 area's. A high voltage AC area and a lower voltage DC area.
AC area is the left side so everything in that area you measure in AC voltage. The otherside is lower voltage like 15v / 5v etc and you need to put your meter in DC mode.

You need to put the meter in dc voltage and put the black probe on chassis and the red probe on one of the pins on the white connector P6. See if you measure 5V. Pin is labeled.
It is ok if you measure like 4.5v.

Good chance your mainboard is dead OR your powersupply does not provide the 5v to the mainboard. Mainboard turns on 5v STB ON.

[Moreno83]

Re: panasonic tx-p42ut30b

The fuses are rated differently. 4Ampere and 10Ampere for example.

The coloured area on the bottom of the board are fets and they are labeled with "Q". Measure outer pins , beep is usually bad.

[gobby009]

Re: panasonic tx-p42ut30b

moreno did you read my first comments.i put the probe on every one of the p6 connections and i wasnt getting any readings.

[Moreno83]

Re: panasonic tx-p42ut30b

You were not really clear how you measured and WHAT you measured. Never mentioned the P6 connector.

[gobby009]

Re: panasonic tx-p42ut30b

i measured the p6 connector in dc mode with the tv power on and i wasnt getting any readings from any pin.

[dick_barton]

Re: panasonic tx-p42ut30b

i then turned it to ohms if thats the right setting on my multimeter see picture and it reads 3.7 and kept tripping my eletric.

Voltage and current are read when the power supply is on, ie your tv switched on.
Ohms are measured when the power to whatever you're checking is turned off and unplugged.
I would suspect that if you attempted to read ohms across the Live / Neutral power input with the power on you have damaged your multimeter. No surprise it was tripping the supply.

You need to read through as many threads as possible to see how various measurement and checks are carried out on the power supply. Pay careful attention on how to make measurement on the HOT (Live) side of the power supply and COLD side of the power supply.

[Moreno83]

Re: panasonic tx-p42ut30b

i measured the p6 connector in dc mode with the tv power on and i wasnt getting any readings from any pin.

Black prope on chassis and red prope on p6?

[gobby009]

Re: panasonic tx-p42ut30b

yes black probe on chassi and red probe on each connection on p6.i done the p6 check before i did the r104 check.so my multimeter was working fine

[Moreno83]

Re: panasonic tx-p42ut30b

Ok , did you check the fuses already?

Make sure there is no voltage on the tv. So remove the mains.
Meter in continuity mode ( beep ) and put one probe on one side of the fuse. Other probe on the other side. Beep is usually good.

There has to be continuity on the fuse to let current through.