Fitting A Universal Board And Inverter In LG TV Model 32LN5100
This LG TV belonged to a close electronic technician, who switched over to Electrical and plumbing works. This defective TV was given to him by someone and handled by a few technicians unsuccessfully. The reported defect, which was confirmed by my test too, was the set got switched on, with no display and none of the controls worked, including from the Remote Control. After opening and cleaning the set, when I checked up, found that all the voltages on the Power supply were present: 5V, 3.3V for standby, 12V for panel and 24V for audio section. The voltage of around 33V for the inverter section was also present.
Looked for any burnt/burst components on the main board and did not find any. Downloaded the schematic of this TV and found that the slave power regulators were also giving out proper outputs. The IC was getting the required voltages at the pins marked in the circuit diagram. The power on for inverter and panel were not coming out from the IC, though it got released from the standby. Then, on enquiry with my whatsapp group, many conveyed that failure of the uController IC was quite common in LG and even if we replaced the IC or the full board it, it would fail again. Moreover these were very costly too! I wrote a feedback to CEO of LG about this as well as failure of backlight which are reported to be quite common in LG models and got an acknowledgement too from them. Though many of my friends objected to my action, siting that it was a sort of self-destruction, as the bread and butter of all electronic technicians who solely live from its income depended on such failures, I gave more weight to my responsibility as a citizen to protect the interests of the mass, who bought these TVs. I believe that it is incumbent on each and every one of us to bring such common issues to the concerned giving chance to take corrective action. I have never hesitated to highlight and draw the attention of the concerned authorities whenever I have found an anomaly in public services or any such incidents that affected the public.
Let it be a public convenience, service or other, I never thought it a botheration to write a complaint or give feedback to the concerned. Same applies to appreciations too! I have submitted or written several feedbacks whenever good things or services were observed. As a responsible citizen, we should be a part of the system and help it progress in the right direction by our active involvement. Now let us have a look at the boards and the acknowledgement from LG:
(To zoom and read, kindly press control key and scroll up/down as advised by Jestine Yong)
Since the cost of replacement of the board or IC was prohibitively costly and stood a chance of repetition of failure, as already mentioned by me earlier, I went ahead and ordered for the following Universal Board with its accessories:
This is commonly referred to as U11 board. I learnt all these from my techie friends. Being my first attempt in fitting a Universal Board in an LCD TV, I took guidance from them for the step by step action. By default the jumper switch is connected to 5V. So, I changed it to 12V, as the panel of this TV worked on it. There is an option to select 3.3V too on the board. The external connections that go to the inverter are marked on the backside of the PCB.
The main points to be taken care of by us are (1) Panel voltages, 3.3V, 5V or 12V (2)Type of LVDS cable, i.e., power supply pins on left or right; T-con/Scale board side connector facing up or down 3) HD ready or full HD panel. For HD ready panel, the connector will have only around half the data connections but for full HD panel, these will be almost full. In this case, the TV was HD ready, with a resolution of 1366×768, whereas for a Full HD the resolution is 1920×1080 pixels. And I required an LVDS cable having power supply on the left and facing upwards, as can be seen from the following picture of the T-Con Board:
I had bought a 12V, 5A adaptor with the Universal Board along with the extra accessories ordered for keeping a standby board and power supply. I powered the Universal Board and found it to be working. When we connect the power and switch on, the LED will light in red colour and when we press the standby, it changes to blue. Kindly see pictures below:
I connected the cables and wired the 12V supply from LG’s original power supply board and return connection for standby and power on from the Universal Board. But the backlight did not get on, though the power on was ok and power supply to inverter side was also ok. The backlight was ok when I isolated its connection and checked it with an LED checker. So, the problem was in the inverter side. I looked for any defective components in and around the inverter IC and could not find any. As the inverter section was defective, I decided to discard this bulky power supply board and use the Adapter. Then fit an inverter board in its place and provided the power supply and other power on and dim connections from the Universal Board. After this, when I switched on the TV was working, but with a different resolution. Using the Remote, I input numbers 20081 upon which the resolution got adjusted to 1366×768.
The inverter was also working very well with a 67 V supply at around 100mA current.
Next job was to cut the back cover to fix the Universal Board, as all its connections were on the side. The case bought for fitting the Universal Board had to be housed properly. I kept the case and marked the area to be cut. Then cut and removed the plastic portions from there. I could fix the case properly after repeated cutting and filings.
I made space for the lengthier sensor PCB in the same place where the original was and inserted it there.
After completion of all the internal wiring and placement, fixed the back cover and allowed the TV to run for several hours. It worked very well adding great satisfaction to its collection bag and drawing curtain on this article.
Those of you who are interested to know more about the Universal Board, kindly see it in the following link: VS.T56U11.2 Universal TV Card Full Details – Dip Electronics LAB
This article was prepared for you by Parasuraman Subramanian from India. He is 72 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.
Please give a support by clicking on the social buttons below. Your feedback on the post is welcome. Please leave it in the comments.
P.S-If you enjoyed reading this, click here to subscribe to my blog (free subscription). That way, you’ll never miss a post. You can also forward this website link to your friends and colleagues-thanks!
You may check on his previous article on How To Repair Projector With Auto Shut Off Problem