TV Set Top Box Repaired
Fault Symptom: Set top box doesn’t release Standby Mode.
I was watching TV and suddenly set top box was shut down after turning power ON again it does not change light sequence (when set top box was in working conditions there were three lights up in sequence on startup. first standby, remote and Alert after the process of start up only one light glowing that is Red and it becomes Green when pressing On/Off switch from remote control.)
So here problem is when I press the button on Remote control there is no effect on set top box red standby light not changes to green.
I have doubt on remote control so I have checked working of remote control switches under Mobile Camera found Ok (Pressing switches while IR Sensor facing towards Camera of Mobile phone it shows violet light glowing when you press any switch)this way remote found OK.
Now standby light is showing that means power adapter is also OK. For further inspection I have opened the Unit to find what wrong inside is.
On opening I found the layer of dust over the components….
So I have cleaned the dust using IPA & turpentine and of course with using dust mask on the face.
It is very irritating work for me to clean the dust because I have severe sinus problem sneezing at least 15 to 20 times when dust get triggered in nose. But what can be done work is work.
After cleaning process done with using hot air blower I have given heat on main IC & surrounding components so that IPA & turpentine will evaporate from underneath of components.
Reassembled the unit after completely dry up of the PCB. And for testing I have fitted the unit with my setup and turned it on with remote control now standby light is release from Red to green and now TV programs get start to work.
Sometimes problem solving is not that hard but it becomes hard when we do over thinking before analysis. I have also done these mistakes in past that assuming unavailability of tiny SMD cannot solve the problem & I just scraped the equipment. Also spending time for repair is not worth……. But every time components are not at fault………………..
This article was prepared for you by Yogesh Panchal who works as a Computer Hardware Engineer in Mumbai India.
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Note: You can check his previous repair articles in the link below:
https://jestineyong.com/computer-atx-smps-no-power-repaired/
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Albert van Bemmelen
November 21, 2020 at 4:53 pm
Glad to see that just removing the quite alarming layer of dust worked to restore your tv settop box's functions. Using your mobile phone to check your IR remote control is a smart thing to do. I also noticed the way in how you managed to make your soldering iron holder safer by wrapping a metal mesh around the spiral holder.
Yogesh Panchal
November 21, 2020 at 9:53 pm
Thanks!Albert
"Necessity is the mother of invention"
Yogesh Panchal
November 21, 2020 at 9:54 pm
Thanks!Albert
"Necessity is the mother of invention" when you do not have proper resources to eliminate the problems.
babums
November 21, 2020 at 11:07 pm
I have learned lesson from your article that dust can create this much problem and very well explained the repair work. Thank you very much and expecting many more article.
Yogesh Panchal
November 23, 2020 at 5:08 pm
Your welcome! Babums
Anwar Y Shiekh
November 22, 2020 at 7:05 am
Doesn't turpentine leave a residue?
Yogesh Panchal
November 23, 2020 at 5:13 pm
No it does not leave residue it will get evaporate in just few minutes you can use air blower for fast result and i think it is better than 70% IPA which is more watery or IPA should be more than 90% is best for PCB Cleaning.
Humberto
November 22, 2020 at 11:00 am
Too much dust, what a job!. But finally the set was saved.
Yogesh Panchal
November 23, 2020 at 5:17 pm
Humberto,
you are right Dust + Humidity are the main killer of electronics equipment.
Mike Retz
November 23, 2020 at 6:36 am
Yes sir. Dirt and dust can cause a lot of proubldms especially in electronics and overheating. I use wd40 to clean boards but with great care because it is extremely flammable. It is possible that just using the turpentine fixed your proublem by correcting an intermittent solder connection that may have corroded. Older crt tv tube chassis used pc board mounting stakes as ground connection back when. When the set got old these connection would fail sometimes from heat and dirt and corrosion . Sometimes set work sometimes not. This was filament ground connection and would drive techs crazy. Go around to front of set no pix, by time go to back of set vibration would correct proublem and cust say pix ok. Clean board with with wd40 and set work perfect. Leave 2 weeks later weather dry out and cust call back and say pix bad again. When weather wet pix good . Told cust don’t watch tv when dry out! Have great day!
Yogesh Panchal
November 23, 2020 at 5:42 pm
Mike Retz,
WD 40 leaves a residue and it is great magnet for the dust & again you need to use IPA to clean it.it is basically a Lubricant and one of the best substance to open rusted Nut and Bolt & good rust remover, it is OK to use when your PCB is water damage.
Parasuraman S
November 27, 2020 at 9:13 pm
Good job there, especially carrying out the inevitable cleaning job, risking your health! That is dedication! Many thanks for sharing!
Yogesh Panchal
November 30, 2020 at 10:58 pm
Thank you! Sir
K Vaibhav
July 12, 2021 at 8:49 pm
Hello Yogesh Sir, You are like to save the set-top box easily, but I have to face the same problem but unfortunately not solved as you have, can you help me to solve my set-top box problem, it's the same model like you show in your above picture, and the problem is restarted repeatedly after some time of powered ON. First, I check the Remote control it is OK, then change the power adapter with the same voltage and current rating, still have to face the problem, so open the set-top box first to clean up and visually check no any damage or burning sine on board, then check voltages all is OK, at the testing time I found that the main processor is heated and then reset the set-top box, I try to find out the problem could not any result, and one thing when it is reset the voltage of SAT In section voltage is changed 0 to 19V. Request to guide us, if have any solution to solve the problem.