Re: A guide to fixing/troubleshooting some common plasma TV problems
You may have a faulty Y-Sus if the fuse blew. Here's what I'd do:
(1) Check all Y-Sus and Z-Sus fuses.
(2) Check all standard panel voltages:
Power supply: VS and VA
Y-Sus: VSC and -Vy
Z-Sus: Vzb (aka Zbias)
Edit:
If you're unsure how to do the voltage checks, I can diagram them for you tonight. Also, there are lots of threads that mention the voltage checks specifically for LG-based TVs like yours.
Re: A guide to fixing/troubleshooting some common plasma TV problems
Ok, here you go. The voltage checks are listed on the pictures I've attached. The black and red arrows denote the black and red probes. If there is no black arrow included for a test point, that means your black probe should be placed on chassis ground (a metal part of the back of the TV is fine). Post a pic of the panel label that lists the voltages so we can help you compare your readings to the label.
Re: A guide to fixing/troubleshooting some common plasma TV problems
Tom. this is a great help. Thank you for taking the time to break it down..Although I do have a problem with a set that i am working on, that is real similiar to your posts.. I have a 50pfp5332d/37 and it came to me with sound and no picture. Normally i would do a little testing and then replace the x or y sustain boards.. Although I have been working to become more confident in component level repair. So guys with this being said voltages were a little off and i was thinking that something was dragging them down or bumping them up. so i've checked all fuses including the thru-hole and sm ..All fuses are good, so i was looking at the ysus and noticed that the voltage on the lower half was gone and like 1/2 of what things should have been.. Then I notice a mosfet or power ic 7 leg MR4720 is the part number marking and a pin is burned in half. so I have ordered a couple of them, only available from hong kong, and am waiting to see if this fixes the set.. I guess my question is DO YOU THINK SOMETHING OTHER THAN THIS PART CAUSED IT TO FAIL? I iwll let you know once that part arrives abd soldered in. Is there anything else I should look for? I will post a pic of the part and the location on the board tomorrow. thanks again jamie
Last edited by jamie_ydr; 11-01-2013, 12:35 AM.
Reason: wanted to add information
Re: A guide to fixing/troubleshooting some common plasma TV problems
vinceroger69, thanks for the link there is some really good inforamtion here. thanks again..If anyone knows where i can get ccfl replacement tubes for sharp lc6554u sharp 65" i need ccfl. also if there is a way to trick the set into thinking it has the bulb please post or nessage me. I have one bad ccfl in the set and have moved it to the bottom of the screem but cant find a replacement and have a huge tv taking up space in repair area due to bad bulb..thanks jamie
vinceroger69, thanks for the link there is some really good inforamtion here. thanks again..If anyone knows where i can get ccfl replacement tubes for sharp lc6554u sharp 65" i need ccfl. also if there is a way to trick the set into thinking it has the bulb please post or nessage me. I have one bad ccfl in the set and have moved it to the bottom of the screem but cant find a replacement and have a huge tv taking up space in repair area due to bad bulb..thanks jamie
Defeating the bulb detect can be done if you have a schematic of the inverters; do you? Best put this in your own thread.
Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.
Re: A guide to fixing/troubleshooting some common plasma TV problems
Ok this is what I got
Vs-172.9
Va-55.4
VZb-.60
Vsc 1.26-9.94 fluctuated between these numbers
-Vy .7-1.5 fluctuated between these
Hope this helps us trouble shoot
Re: A guide to fixing/troubleshooting some common plasma TV problems
Your Vs is really low - unlikely to be your problem but do adjust it later.
-Vy and Vsc are faulty which indicates a Y-sustain fault.
Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.
Re: A guide to fixing/troubleshooting some common plasma TV problems
Agree with Tom. The Vzb is also low or not measured correctly. It should be 100V. When the fuse on the Y-Sus blows, it's usually an indication that the large IC under the big heat sink has shorted.
Re: A guide to fixing/troubleshooting some common plasma TV problems
Good catch didn't see that.
Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.
Re: A guide to fixing/troubleshooting some common plasma TV problems
At a minimum, your Y-Sus is bad. Your Z-Sus may also have issues if the Vzb voltage reading you posted is accurate. Typically, the recommendation is to replace the large IC on BOTH boards at the same time.
Re: A guide to fixing/troubleshooting some common plasma TV problems
Ok Tom, here are the pics of the back of my TV. To refresh, it is an LG. Model no. RU42PZ61. I have located the place to send the board for repair, but need to know which part I am supposed to remove.
So here is a pic of inside. This is with the small access panel removed. Do I have to remove the entire back or just the smaller access panel? How do I know which part I am after?
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