Re: Lg plasma problem please help
If I remember the jist of this block of videos:
[url]http://www.youtube.com/channel/UCPCEiKNb0Fx76jWZgiuqnUw/videos?flow=list&sort=dd&view=0[/url]
one or both of the power resistors in the upper right-hand corner (when it's installed in the TV) of the power board start to head south, I think they were 22 ohm and rated for 5 watts. That would be my first check.
That in turn can possibly cause a 6-pin voltage regulator, a diode near that regulator and fuse near them to all give up the ghost. That would be next.Re: Lg plasma...
Rack
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Last Activity: 01-30-2016, 09:31 AM
Joined: 02-16-2010
Location: Cedar Lake, IN
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Last edited by Rack; 02-11-2013, 08:02 PM. -
Re: Hitachi 55HDT52 no picture, no audio
Not that small of a world, still takes the better part of an hour and a half to get from me to you, Dennis H.!
I did most of my measurements with the boards still in the TV, but I took out the buffer boards and Y-SUS to give them a closer look, and see just what went wrong. From the picture, you can see one of the buffers got hot, but it seems only that one. Using the video tom66 posted, that was the only buffer chip with issues, but when I tested the buffer ICs while it was put together, every other chip was "bad"....Leave a comment:
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Re: Hitachi 55HDT52 no picture, no audio
There's a transistor, Q1515, that is connected to Vs at its drain, some other section at its gate, but from its source, it goes through a couple power resistors in parallel, to a little transformer, then past a capacitor on the way to Va. Nothing tests unusual.
I checked the other thread (Dennis H's) and saw that tom66 posted posted some troubleshooting guides, so I checked out the shorter one:
[url]http://www.tgohome.com/ServiceManuals/Hitachi/Hitachi_DW3_P42H401_P40H4011_P40T501_P50H401_P50H4011_P50T501_P55H401_P55H4011_P55T551_P60X901_Dead_Tips_[/url][TM].pdf...Leave a comment:
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Re: Hitachi 55HDT52 no picture, no audio
I'll have to work on finding a better camera, no one comes to mind at the moment.
Working back from the Vs pin, I see two diodes, D1529 and D1503. In diode testing mode, my meter reads 0.420V drop across both of them. The input of the diodes comes from pin 9 of the transformer T1502. The output of the diodes goes past a bank of capacitors, 4800uF in size, my meter read 4900ยต in-circuit. At this point I wish I had an ESR meter, it'd be useful information to have. The output continues to a circuit that starts at my rectifier diode...Leave a comment:
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Re: Hitachi 55HDT52 no picture, no audio
There just seems to be the one feed for Vs and Va coming from the CN64 connector on the power board, and for the Force Voltage test, the CN64 cable was disconnected.Leave a comment:
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Re: Hitachi 55HDT52 no picture, no audio
Sure! They are labeled as 10 ohms, they test at 10.3 ohm each (20.6 ohm in series).Leave a comment:
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Re: Hitachi 55HDT52 no picture, no audio
Yes, I do get a relay click when I turn the TV on with jumpers.
I was digging through the service manual some more, looking for more information.
Vcc is supposed to be +5.1V, it's a label, not a sum.
24V is supposed to read closer to 25V, 22V would be quite low.
16V is supposed to read closer to 16.5V, so 15V is pretty low as well.
10V is supposed to read closer to 10.5V, so 10.7V is okay.Leave a comment:
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Re: Hitachi 55HDT52 no picture, no audio
Sure, but the pictures will be bad since all I have is an old iPod.
The heatsinks kind of get in the way of most of the caps on the topside of the board, but none of them look bulged in any way. Maybe I could get in closer with some more light if you wanted a closer look at something in particular....Leave a comment:
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Re: Hitachi 55HDT52 no picture, no audio
I did check the fuses I found, they all had continuity. They were labeled F1AH, F2AH, and F5AH. I looked for possible F3 and F4 fuses, but I didn't see any.Leave a comment:
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Re: Hitachi 55HDT52 no picture, no audio
VS-ON, not sure. I have a STBY2 and STBY3, which are jumpered to standby3.3V for the stage 1 power board test. I do have Vsago and Vcego which are jumpered to standby3.3V for stage 2 of the power board test.Leave a comment:
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Re: Hitachi 55HDT52 no picture, no audio
As part of the test procedure, both the Y-SUS and the X-SUS are disconnected before starting, I forgot to mention that.Leave a comment:
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Hitachi 55HDT52 no picture, no audio
It's the same TV as in this thread (assuming Dennis H just kicked two letters around):
[url]https://www.badcaps.net/forum/showthread.php?t=25765[/url]
with a different issue, though.
Service manual link:
After I opened up the back, I saw that the power LED wire was disconnected. After connecting that, I got a red light, solid. Upon turning it on, I got a solid green light, then it blinked 10 or 11 times, then a solid green light. The "Knight Rider" diagnostic on the main board was on "Flash Memory/Loading Program" when the...
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