TV Repair Questions? Ask a TV Technician
Hello. My name is XXXXX XXXXX I'll be assisting you. You say it doesn't work from the analog inputs. Are you talking about the composite or component inputs? If that is true, the HDMI connection board is not your issue. Please check all the inputs and get back to me. I'll know more when I have that info.
Thanks for your time.
Yes, they are the composite/component inputs (RCA Plugs). Just to let you know, when I replaced the HDMI board the first time, all other inputs (HDMI and composite inputs) also worked. I think these are affected when the HDMI board go bad. Like when it broke initially, the screen was blank and has no sound. When I use the SD Card, It will still load and show pictures from my SD Card clearly.
By the way, when I connect the Logitech WebTV device, the Logitech boot screen will show up on the screen (clearly) but will disappear after booting. The Direct TV Box will not show anything at all. The Sony Blu-Ray will show but has no sound.
Wow. You have mixing and matching problems. OK. Just so we're clear, the RCA jacks are used for both the composite and component inputs. The yellow cable is the composite plug. The composite input is both lumanance(picture black and white portion and chroma(the color portion). These are both displayed from the one cable. The composite are, in esance, red , green and blue. There is a bit more to the component video than I just mentioned, but that is the gist of it. Both of those inputs would require either a analog left and right audio, or coaxial/optical audio input. So could you please tell me again, exactly what cables you're using for the video and audio, other than the HDMI cable.
On another note, are you a tech, or an end user? Needless to say, there is a great risk of electrocution with the unit disassembled An Isolation transformer should be used, at the very least. Please get back to me with all the details, and we'll take it a step further. On a completely different issue, if we are to continue troubleshooting your LCD, the rate you chose really should be increased. I don't mean to be rude, but you're asking for allot of technical savy for $14.00. I hope you don't take that the wrong way. A quick answer, depending on the topic is worth $14.00, but we are going to go way beyond a quick question.
To make it simpler, I only tried to use the yellow/white/red cables to test my external devices after the TV went bad. When it was set up this way , I only got white images but with sound. Typically, I only use the HDMI inputs. When using either HDMI input, the screen remained blank and has no sound.
I am not a tech. I am an en-user with electrical engineering background but with little understanding of current electronic technolgies.
OK. Let's give it one more shot at this price. Anything elex
else, we'll have to arrange a fair bur economical price. OK? Now let's back up a bit. What I want you do do, is use the component in, R, G, B, but you will need to use a coaxial or digital input OR analog L and R, for your audio input. So we are on the same page, the only audio you can provide it is: the HDMI, which carries audio and video, or the analog L and R, or coaxial or optical input. You have none of these presently. Try using just the DVD as an input, and connect it that way. If that doesn't work, try the Direct box. Please make sure you select the correct inputs using the menu. I assume that the menu comes up when you press MENU on the remote, correct? If it does, approximately 75% of the TV is working. If not, stop there as you have a much bigger problem just than just an input selection.
I just did what you suggested. I used the R,G,B in component 1 with the audio cables. The result is the same as when I used the Yellow/White/Red cables. I got the white images and sound.
What about the menu? Does it come up in color? Can you please try a composite(yellow) input. Which audio input method are you using?
The menu comes up normal, i.e., in color. I tried the video composite input (yellow), as well as the audio (red and white RCA jacks) in inputs 1, 2 and 3 (one at a time). Audio is okay on all but I still get the white (distorted) images in the screen on all three inputs, similar to what we tried yesterday. The TV is equipped with an SD card reader. When I insert an SD card to view pictures, it works fine. Pictures are sharp and colors are good.
OK. If you would like to increase your deposit to around $30., I will continue to assist you. I hope you understand my position.
Thank you. Please let me know what you wish to do.
When I signed in to this site, my understanding was the $28 fee was to get a satisfactory solution to my issue. I actually have performed all the tests you asked me to do even before you asked to. I believe that I have explained that in our earlier communications. However, you really have not even suggested any diagnosis or solution to the problem. I think I know how you operate, i.e., you to do your troubleshooting step by step. I do agree with that approach but that leads to more back and forth questions and answers. But that is the consequence of this approach. I just don't think it is fare to pay more now if I have not received any kind of solution or diagnosis. Don't take me wrong either. I am actually willing to pay if I get a satisfactory answer.
Now, you replaced the DG BOARD --
Replaced the HDMI DG Board (TNPA3903 BCT
HDMI inputs don't work
if i use the analog signal from my external devices, I get white images with sound
Direct TV box is connected to HDMI 2 input. My Blu-Ray is connected to HDMI 1 input
I only tried to use the yellow/white/red cables to test my external devices after the TV went bad. When it was set up this way , I only got white images but with sound. Typically, I only use the HDMI inputs. Note - Component had the same results as AV
when I replaced the HDMI board the first time, all other inputs (HDMI and composite inputs) also worked.
Your original board -- when it failed, did the HDMI fail, and the RCA inputs exhibit the WHITE PICTURE ? Or did the WHITE picture start showing up AFTER you replaced your Board in the TV set?
Ok, I have a tendency to use pictures, not only for me, but for you too.
I have X ed the BAD signals, Checked the Good signals and that way we can effectively see what possible failure points we have (in blue)
Now, I will tell you that initially, I would have replaced the DG board. After finding out the SAME SYMPTOMS that you had has not changed...and the FACT that your H board <<MIGHT>> Not affect the HDMI signal.....
AND the fact that your Power supply seems to affect ALL boards (unless there's a dedicated voltage that only powers the DG and/or the H board.
I've come to the conclusion that your symptoms may point to a power supply issue, OR possibly an issue with a Video Data Bus being pulled LOW !
I am an en-user with electrical engineering background
That's GOOD....do you happen to have ACCESS to an oscilloscope ??
When it comes down to it, I'd be looking seriously at a DATA-Bus issue, although the SD card seems to create CONFLICT with that assumption.
Another CONFLICT....the power supply board isn't causing MORE symptoms related to powering on, and lighting up the panel.
The 15 Volt line operates the lower voltage regulators on your NEW DG BOARD, and while it's suspect, the 15 Volts (separated multitaps) also controls the Display panel Drivers.
So....logically if we take a look at the data bus and the 15 Volt supply we may just figure out WHY your TV was working fine for only a couple days.
My experience....data bus problems behave the way you described.
I'd be trying to verify it's running a good solid 5 Volt datastream...with a scope.
What say you ??
Bulged tops....REPLACE IT.
Any near a heat sink that could get hot....replace it
KEY IN on only the caps that are rated at being used on a 5 Volt line ! 25 Volts or less if that's what your bulged cap is.
This is what I'm thinking.....
I think the 5 volt supply could be messing with the digital data bus that communicates with the H and the DG board !
The only two supplies that I'm PRESENTLY aware of would be the 5 V and 15 V supplies so we should seriously concentrate on making sure the power supply voltages are RELIABLE.
After all.....my first mentor told me to ALWAYS check the power supply voltages FIRST.
Then you start isolating any issues left over.
I doubt your DG board is bad...I think the voltages to it are low.
5 Volts is bad if it's out of 10% of desired voltage, so at 4.5 volts....it's bad.
Even 4.6 isn't good to me. 4.8 to 5.1 is ok in my book.
Now the reason I emphasize the 15 Volts too....it runs some very low voltages used to power up the ICs on the DG board.
If you have a soldering iron, it's just as easy to replace the bulged caps.
If the caps in the Red box are the ones you find BULGED --
Then those are the ones I would expect could cause your problem.
Any others are too large and too high voltage to affect your DG board.
I will let you know that P25 plug on the power supply seems to run over to the D board. There the voltages get delivered to the DG board. Regulation /stepping down the 15 Volt line to micro voltages are done on the D board, but those are 3.3, 1.8 and 1.2 Voltages. The D board I don't believe is involved. The SD card works fine.
Replace those caps, and if you need more info to help, let me know.
I'm pressing the ANSWER BUTTON, but that doesn't mean it's the ANSWER.
It just locks out the information to the search engines out there.
There is another button besides the ACCEPT button....use that, not the ACCEPT....at least not until we are done, ok?
Third LARGE cap from the lower left?
That one is one of the MAIN filtering caps. I really doubt that would affect the TV simply because it's what we call a RAW DC filtering cap. There is a regulator that would effectively filter the DC voltage so the 5 V and 15 Volt secondary wouldn't even see a low voltage caused by it.
Besides, the bigger cans like that usually aren't the cause. I'd really be looking at the caps highlighted in the red box I drew. Those are the FINAL filtering caps before the voltages get sent to the H, DG and D boards. Those are the ones I'd be replacing.
Use your voltmeter to find the 15 and 5 Vdc lines going to the P25 plug. Measure them for DC first, then switch over to AC and see if you get any AC ripple on them. Usually dried out caps would exhibit AC ripple or just a lower DC voltage on them.
And if in doubt....replace them so you know 100% that the filters are doing what they are supposed to.
And if in doubt....replace them so you know 100% that the filters are doing what they are supposed to. If you had an ESR meter...I'd be checking the ESR on the caps. ESR = Equivalent Series Resistance. That simply checks the ability of a capacitor to FILTER AC ripple to DC voltage.
Caps act like batteries. They store a charge. Pulsating DC gets converted to pure DC with no ripple. That's why an ESR meter is so helpful with Caps. It simply measures the ability of Electrolyte to absorb/store ripple.
Think of a cap that's like a Half -Filled battery. Or a sulfated battery. Dried out or partially shorted, a battery cannot store enough energy to drive the load. Your load is the H, D, and DG boards.
If that BIG cap was heavily DOMED...then I would replace it. Genty curved...NO...I wouldn't worry about that.