TV power supply question - Page 1
Forum section: electronics / beginners

author: whaase
author_rank: Contributor
timestamp: February 10, 2016, 09:05:02 pm
content: I have a TV I'm trying to fix (For a while now). I do know a bit about electronics, but not as much as I need/wantThe power supply is making a weird buzzing sort of sound and will eventually shut off until it cools down. Attached is a video of what I'm looking atI think the sound is coming from one of the grey rectangular capacitors that are below the small heat sink. It is marked on top MKP 25 - 150K 450V.http://vid1202.photobucket.com/albums/bb364/walterhaase/Mobile%20Uploads/tv.mp4Can anyone direct me what to test or my next step?Thanks, Walter

author: Nickk2057
author_rank: Regular Contributor
timestamp: February 10, 2016, 09:37:39 pm
content: what is the model of the TV? and have you also checked the capacitors as well to see if they are bulged?

author: whaase
author_rank: Contributor
timestamp: February 10, 2016, 09:43:19 pm
content: Its a Dynex 46" LCD from 2011.Model is DX46L262A12No capacitors are visibly bulged... I wish they were lol it would be easy thenWalter

author: Adam60
author_rank: Regular Contributor
timestamp: February 10, 2016, 09:44:34 pm
content: Make, model and a good set of pictures showing the complete power supply board. What are the output voltages on the connectors? Are the electrolytic capacitors bulged on top? Good place to start.

author: whaase
author_rank: Contributor
timestamp: February 10, 2016, 09:59:23 pm
content: 24v was all over then faded away, 12v just slowly dropped and the 5v was solid.I also attached the service manual I found for itWalter

author: whaase
author_rank: Contributor
timestamp: February 10, 2016, 10:03:25 pm
content: Link to service manualhttps://www.dropbox.com/s/6w5g1dp0jvh570j/dynex_dx-46l262a12_sm.pdf?dl=0

author: Adam60
author_rank: Regular Contributor
timestamp: February 10, 2016, 10:06:26 pm
content: Can you attach it another way for those of us who do not use Dropbox?

author: whaase
author_rank: Contributor
timestamp: February 10, 2016, 10:12:09 pm
content: Hmmm, I will try Google. Hopfully that workshttps://drive.google.com/file/d/0B-v7N6Vffcj7NWZ0WDZLbzdYUjQ/view?usp=sharing

author: Adam60
author_rank: Regular Contributor
timestamp: February 10, 2016, 11:59:59 pm
content: O.K. Little information to go on so far and schematic unclear. Does red light come on/stay on? Does it change color when switched on? Can you check all voltages and provide them in an easy to read format, both before and after switching on (cold) and after it fails. On all connectors?I atill have suspicions about caps.Do you have cap tester and ESR meter. I am thinking you have high ESR on the caps and this causes your issue. Common on this TV now that we know what it is? Roughly 1.5 years old?

author: whaase
author_rank: Contributor
timestamp: February 11, 2016, 01:30:33 am
content: Sorry. The TV turns on as normal. That sound in the video starts right away. It will run for random times. 1 minute one time and 20 the next. It will shut down and need to sit for awhile before it will turn back on.I will get all the voltages for youI don't have a esr meter. I do have a decent multimeter that checks them. I know it's not the same. On a side note, I have enough caps to redo it all if needed.I'll update with voltages asap.Walter

author: Adam60
author_rank: Regular Contributor
timestamp: February 11, 2016, 01:58:50 am
content: How old is the TV?Still suspecting caps. Do you have low ESR caps to replace them. You need good quality Panasonic, Nichicon, Rubycon caps and you will not have problem again for a long time if that is what it is. What brand of caps are in there now? Pearl?

author: Grzegorz2121
author_rank: Contributor
timestamp: February 11, 2016, 11:29:45 am
content: This sounds like relay. Maybe supply are having problems with it.