Question about LG 42PX5D 42 in. Plasma HDTV

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Thanks, but it isnt that simple. Most of the supply rails are OK, but the feed to the ZSUS PCB shuts down under load.........so a problem in just one part of the overall P.S. Hard to work through on the PCB as you need to undo a lot of TO220 components to be able to work both sides of the pcb! Good suggestions! Thanks

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Well I just had coffee so thought I would share tips.

if you do something like I do when working out a system .
shoot a digital picture and print or edit it on-screen.

start by documenting removed and interconnected components.
mark inputs and outputs, then power flow, regulation, feedback
then mark the main divisions to each circuit
look for a data bus. HV area,
document the hot spots and damage
if it can be maintained in shutdown mode what area got cool.
a thermal picture of board would be very helpful but you can map it manually using hands , ir sensors or thermal probe (insulated)

I use an audio probe in a lot of circuits to listen to the signals.
though some scopes have audio and digital capture I found audio to be a lot faster once you get used to it. you can hear heat noise in the dc signals, you can hear caps ticking, data sounds digital. even different voltages have special sounds.

once you make this map of a board you will find troubleshooting much faster and easier as you record the data.

print out a couple of copies and work out a system to get to them quickly.
the hardest of all but necessary is to make a rig to run the unit outside the unit.

Get yourself a good analog meter, on the Rx1 scale it puts out a small bit of voltage so you can test transistors ,diodes and cap all in-circuit , reason. if you watch the rise of the needle and speed it falls, you can tell the overall time of the charge /discharge of circuit or cap.

----------------

It is by caffeine alone I set my mind in motion, It is by the beans of
Java that thoughts acquire speed, the hands acquire shaking, the shaking
becomes a warning, it is by caffeine alone I set my mind in motion.


Posted on Jun 12, 2008

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1 Answer

What does a pcb look like i want to make sure i am right


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You can unplug the connectors to the zsus board at the power supply and try to turn the set on. If it does turn on, the power supply board is ok. If not, the power supply is bad. If the power supply board is ok, undo the plug connectors that power the Xsus board and hook up the plug connectors to the Zsus board. Turn the set an and see if it stays on or shuts down. Part numbers should be on the boards. Zenith is really LG Corp. Their customer support number is 1800-243-0000.
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Loading the paper


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1 Answer

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2 Answers

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1 Answer

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