Re: Panasonic th42pz80u: backlight working but no display
Remember the great words of Bob the builder: Can we fix it? (yes we can)
That being said, I no longer have this TV, so any advice I have would be speculation, but have you popped her open yet? If a lightning strike fried some components, I'd think the damaged parts would be obvious.
Side note: I don't think I ever formally thanked the other regular posters (you know who you are) for all the help they gave me with the Vizio. The TV is still going strong. While I planned on attempting...
Tetranitrate
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Last Activity: 05-12-2023, 05:16 PM
Joined: 12-13-2011
Location: NYC
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Re: Panasonic th42pz80u: backlight working but no display
Brooklyn Poly , which (as of a few years ago) was bought by NYU, so it is now kinda the NYU school of Engineering. The course was a ton of fun; we only discussed displays in a couple of classes. A couple of other cool concepts discussed were plasma ion engines along with the creation of a leading edge of plasma around high velocity aircrafts to reduce the shock of the air pressure.
The A board and D board are separate in this TV. The D board is underneath the metal plate that the A board is...Leave a comment:
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Re: Panasonic th42pz80u: backlight working but no display
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Yeah, I realized that earlier today when I was thinking about how plasma TVs work. (on a side note I had even taken a course called "Intro to Plasma Engineering" as part of my EE degree ... I am glad my professor didn't hear me say that)
As Sal said, the red power on LED is not throwing any blink codes.
We are not getting any audio. To test the audio, I tried both the RCA inputs on the front and the back. We used a remote from a different...Leave a comment:
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Panasonic th42pz80u: backlight working but no display
So my neighbor just put a Panasonic th-42pz80u plasma TV out on the curb. Me and my buddy grabbed it and started trouble shooting. It will power on with a backlight, but no image.
I have attached the service manual. According to one of the troubleshooting flowcharts, the problem is with the D-board. Both the SC board and the SS board LEDs are green.
Does anyone have any suggestions for what to test or issues to look for? -
Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output
If you can get a 3.3v DC source (I used a pair of AA batteries and soldered some wires to the power supply board), I would highly recommend removing the power board from everything and applying the 3.3 volts to the PSON line. It seems like it would give you a definitive answer as to where the problem originates....Leave a comment:
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Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output
I didn't do too much testing on my inverters. With just the power supply and inverter connected, I externally triggered the PSON with a pair of AA batteries and the power supply output the correct voltages, so I figured everything was ok.
I do not know the voltages for the A and B lines, but can check once I take apart my TV again to replace the capacitors on the display board.
I have attached the datasheet for the display board that was in my 37 inch Vizio. It gives some specs for...Leave a comment:
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Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output
Is there a way to identify low ESR capacitors by their package type (ESR can only be measured with a special meter right?). If they can be identified by their package types, does it look like there are any of that type in the attached photo (like the aluminum cased smd ones)? All the orange ceramics I have on hand are in the nF range.
I know I should probably just break down at this point and buy a smd ceramic with known and correct characteristics, but it is just so appealing to think...Leave a comment:
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Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output
Also, is there any reason why I can't use a much bigger capacitor, tape it down elsewhere, and just run a pair of wires to the traces?Leave a comment:
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Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output
I soldered in a small electrolytic capacitor (picture) after testing to make sure it would fit; my soldering job wasn't pretty, but it worked (or so I thought).
I watched a short music video on it full screen and figured, since the TCON board was able to handle it, I had fixed the problem. Today I reassembled the case and everything, wiped down the screen, and put it in my room. I then hooked up my old SEGA and attempted to play some Sonic 2, but the screen started flickering. It would go black for a...Last edited by Tetranitrate; 02-28-2012, 09:54 AM.Leave a comment:
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Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output
Ok, I just started it up without the caps and it worked - at least for the time I left it on (about 10 seconds). It displayed the blue "stand by" screen, and had the channel number in a box in the upper corner. Nothing seemed to blurry, but I didn't really test it with much graphics - I was just really psyched it is working. I swear I am going to frame the tiny single burnt out smd capacitor as a trophy.
Anyway, now that the issue is almost completely resolved, why are you (tom66) against...Leave a comment:
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Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output
No, I have not tried powering it up yet. I guess that would be a good idea before I start soldering stuff onto the board. One of the symptoms was fuzziness or dimness - would this be because there is no extra filtering portion from these caps, so the voltage going into the TFT will not be very smooth?Leave a comment:
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Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output
I have a few electrolytic capacitors that would fit, but I will only be able to fit one (I was thinking I may add up a few to get the correct values, but there is not enough space).
One is labeled 33 μF and 16v, and has a multimeter reading of 36.6 μF. The next nearest is a 22 μF and 50v which has a multimeter reading of 20.5 μF.
A picture of both caps is attached. Any opinions on the matter?...Leave a comment:
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Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output
I brought the board to school with me and used a hot air rework station to pull both caps off. I did a slop-nasty job of it, but in the end got the caps off without damaging anything (picture).
One of the caps is shorted at about 1 ohm. The other capacitor [I]seems[/I] to be fine and reads 15-17 μF with a resistance in the 10's of thousands of ohms. With both caps off there is no more short on this portion of the PCB, and the resistance between the traces where the caps were is now something around...Leave a comment:
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Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output
Good call.
I think I will bring the board to school with me tomorrow (in a few hours), and use the equipment there to pull off and test the caps. Their numerous shiny fun toys would be much more suited for the smd work. In the meantime I have to start, create, and finish a presentation for my wireless senior design project, which I am to give in a few hours. I love procrastinating EE homework with EE work done at home.
I will report back later today with my findings.Leave a comment:
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Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output
C353 is stand alone, and C321 & C322 are in parallel with each other. The two failed caps (C332 & C334) are in parallel with each other, so I am guessing their capacitance value would be closer to 215 μF. It might possibly be a bit more since if two 353's were to be put in parallel it would bring it up to slightly over 300 μF.
Would my safest bet be to desolder a working cap (like 353), take some definitive measurements, do a parallel combo calculation, and solder in a ceramic capacitor...Leave a comment:
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Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output
I would say (with my limited knowledge) that the low reading is because of the "in circuit" testing, because D90 which is directly connected between the input 12v Vcc and the ground is giving almost the exact same numbers as D302.
Also about the cap numbers being all over the place C323 is distinctly a different color than C332 & C334 (the suspected bad ones). The bad ones look almost identical in color and size to C353, C321, and C322.Leave a comment:
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Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output
D302 .115v with anode to anode, and .501v reversedLeave a comment:
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Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output
C321 & 322 are at 4.47 kΩ and 215 μF
C323 is 13 μF and 37.75 kΩ
C353 is 163 μF and 4.434 kΩ
D302 has 302 Ω (really? is that how they do the numbering for diodes?) and 4.431 kΩ reversed.
RSS065 has 10kΩ S-G, 4.422 kΩ S-D, and 11.88 kΩ D-G.Leave a comment:
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Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output
U302 is 50117B
The resistance readings across all the pins are in the hundreds of ohms.Leave a comment:
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Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output
Haha, you answered my question exactly one minute before I even had a chance to ask it.
On top of the .5 ohm resistance, I just checked the capacitance with my fluke 115 and it shows OL.
How reliable would swapping them out size for size be? I bet I have some SMD capacitors sitting around that match up size wise. Would I really just be able to swap them out?...Leave a comment:
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