Re: Panasonic TX-L50B6B | High pitched noise and black lines
Hello, I'm back with an update. I received my replacement T-Con board, but before fitting I took voltage measurements again, just to make sure I read them correctly first time. They were all recorded correctly as I posted above, including the most suspect one which was CLK1 reading 19.27v.
I've been doing a lot of searching, and managed to find some good resources for my T-Con board (or very similar ones). Turns out CLK1 through to CLK6 should all be around 6.5v, which makes my reading for CLK1 very suspicious...
oldmanhouse
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Last Activity: 08-11-2023, 02:44 AM
Joined: 03-25-2012
Location: Sussex
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Re: Panasonic TX-L50B6B | High pitched noise and black lines
Thanks budwich, I think I'll remove the LVDS cable and t-con cables and give them a clean next time I have the TV apart. If the t-con replacement doesn't work, I'll disassemble further down to the driver board and have a look for shorts/burnt out components there..
I ran the internal screen test on the TV again last night, and noticed the problem is more pronounced when it displaying a red or blue screen (problem less noticable on the black, white or green screens). Also I noticed although the...Last edited by oldmanhouse; 07-14-2020, 02:33 AM.Leave a comment:
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Re: Panasonic TX-L50B6B | High pitched noise and black lines
I found some references to normal t-con voltages on a blog: [url]https://translate.google.com/translate?hl=en&sl=ru&u=https://easywork.com.ua/remont-televizora-lg-32ln540v-za-seroe-izobrazhenie.html&prev=search&pto=aue[/url]
So comparing my readings, they look OK. So I suspect t-con is OK but a "new" one is cheap so worth a shot. I could try replace the ribbon cables to panel (they are removable), but poking/moving them doesn't change the picture so they are probably...Leave a comment:
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Re: Panasonic TX-L50B6B | High pitched noise and black lines
Thanks, I've ordered a recycled t-con so I will see if that rectifies the problem. I'll also do some reading on the tape trick. As I understand it, I need to find the pins which carry video signal and block those, so I'll try and find a pinout for the t-con to panel connections...
Regarding the vertical lines, I've not seen that during normal operation - only when powering the TV up without one of the t-con to panel cables disconnected....Last edited by oldmanhouse; 07-13-2020, 03:32 AM.Leave a comment:
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Re: Panasonic TX-L50B6B | High pitched noise and black lines
Certainly - I've attached them here. Hopefully they are useful, it was hard taking a picture with one hand!
I did the test twice, once where I unplugged the connections whilst power was on (I guess that wasn't the best idea...) and then again turning the power off whilst I removed the connections.
The results were slightly different, when I left the panel on and removed the connection, the picture stayed intact on one side. When I turned the TV on with only one connection, the connected...Last edited by oldmanhouse; 07-11-2020, 03:21 PM.Leave a comment:
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Re: Panasonic TX-L50B6B | High pitched noise and black lines
I've had the TV from new, for 7 years. It's never had a repair performed on it before, and has never had any knocks or physical damage.
Thanks for your suggestions. I checked the A-Board to T-Con connection and it seems OK, firmly seated and not corroded. There's 11.9v on the A-Board side of the LVDS cable.
As the T-Con specs aren't in the service manual, I don't have a reference for what "good" voltages should be, but here they are...
These are from various...Leave a comment:
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Re: Panasonic TX-L50B6B | High pitched noise and black lines
Thanks - I've done as you suggested and removed each ribbon cable from the T-Con to the Panel. I did this whilst the TV was in test mode displaying a picture. The results were:
with left cable unplugged: left side of screen was white (no lines), right side still displayed the picture with lines
with right cable unplugged: right side screen was white (no lines), left side had a garbled picture with lines
The noise was present the whole time, [I]except[/I] once I plugged...Last edited by oldmanhouse; 07-11-2020, 10:27 AM.Leave a comment:
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Re: Panasonic TX-L50B6B | High pitched noise and black lines
A little further information...
I found out about a "LCD Panel Test Mode" from the service manual, which I ran last night. It displays test patterns on the screen for observation of visual defects. Quote from the repair manual:
I observed visual defects during the test mode, so based on the above it must be a LCD Panel fault. My question is, could that also include the LD Board or the ribbon connections from the panel to the board?
Regarding the high pitches...Last edited by oldmanhouse; 07-10-2020, 05:11 AM.Leave a comment:
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Panasonic TX-L50B6B | High pitched noise and black lines
Hi folks, I have an issue with my 7 year old Panasonic TX-L50B6B that has appeared within the last few days.
The symptoms are:
[LIST][*] A high pitched "buzzing" / "whining" noise coming from the TV when it is turned on. There is no noise during standby, and the noise persists with all AV connections removed.[*] There are noticable horizontal lines in the picture. Upon closer inspection it looks like every few rows of pixels are dead/black.[/LIST]
Attached is a close-up of the picture in "test mode", to demonstrate the rows of black... -
Re: LG W2242S with burnt out inverter transformer
Update: bought a new transformer (one selldoor linked to), which arrived the other day. Fitted it and monitor is back up and running!
Many thanks to all for the help
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Re: LG W2242S with burnt out inverter transformer
Excellent advice, thanks very much. I'll give it a go in the week when I've some time to dedicate to it.Leave a comment:
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Re: LG W2242S with burnt out inverter transformer
Ah I see, thanks for clearing that up. I wasn't sure which were the secondary and which were the primary, so I just measured them all.
I did take a reading for 7 - 8, but it's giving me nothing just like all the others not mentioned in my list above. Time to buy a new one?Leave a comment:
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Re: LG W2242S with burnt out inverter transformer
Thanks for the insight into how you solved your problem selldoor and thanks for the link - that's half the price of others I've seen on eBay.
I replaced all the electrolytic caps on my board with new Rubycon ones and it's made no difference. I've taken readings from the transformer (in circuit) but I'm not sure how to interpret them. They are as follows (multimeter set at 2000ohms):
1 & 2 - 1037
3 & 4 - 003
3 & 5 - ~005 (approx. as reading kept jumping about, and usually settled...Leave a comment:
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Re: LG W2242S with burnt out inverter transformer
Thanks for the replies guys. I'll replace the caps as they're cheap, and will do some testing of the transformer itselfLeave a comment:
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LG W2242S with burnt out inverter transformer
Hi all
I picked up a cheap LG LCD monitor (model W2242S) on eBay and was hoping it'd be a simple job of replacing some obviously faulty capacitors, but I think there's a little more to it than that.
The screen powers on for a couple of seconds, displays the LG logo and then the display turns off. The power LED stays on. The classic "2 seconds to black", I believe.
The problem (or at least part of the problem) seems to be the inverter transformer as it looks like it's got very hot and left burn marks on the PCB. I'm no expert, so was hoping...
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