REPAIRING AND NOT THROWING AWAY

REPAIRING AND NOT THROWING AWAY

Richtige Fernseher haben Röhren!

Richtige Fernseher haben Röhren!

In Brief: On this site you will find pictures and technical information about Service Modes, Circuit Diagrams, Firmware Update procedure, Disassemble procedure, Universal remote control set-up codes, Troubleshooting and more....

If you go into the profession, you will obtain or have access to a variety of tech tips databases HERE IT IS Master Electronics Repair !.

These are an excellent investment where the saying: 'time-is-money' rules. However, to learn, you need to develop a general troubleshooting approach - a logical, methodical, method of narrowing down the problem. A tech tip database might suggest: 'Replace C536' for a particular symptom. This is good advice for a specific problem on one model. However, what you really want to understand is why C536 was the cause and how to pinpoint the culprit in general even if you don't have a service manual or schematic and your tech tip database doesn't have an entry for your sick TV or VCR.

While schematics are nice, you won't always have them or be able to justify the purchase for a one-of repair. Therefore, in many cases, some reverse engineering will be necessary. The time will be well spent since even if you don't see another instance of the same model in your entire lifetime, you will have learned something in the process that can be applied to other equipment problems.
As always, when you get stuck, checking out a tech-tips database may quickly identify your problem and solution.In that case, you can greatly simplify your troubleshooting or at least confirm a diagnosis before ordering parts.

Happy repairing!
Today, the West is headed for the abyss. For the ultimate fate of our disposable society is for that society itself to be disposed of. And this will happen sooner, rather than later.

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..............The bitterness of poor quality is remembered long after the sweetness of todays funny gadgets low price has faded from memory........ . . . . . .....
Don't forget the past, the end of the world is upon us! Pretty soon it will all turn to dust!

©2010, 2011, 2012, 2013, 2014 Frank Sharp - You do not have permission to copy photos and words from this blog, and any content may be never used it for auctions or commercial purposes, however feel free to post anything you see here with a courtesy link back, btw a link to the original post here , is mandatory.
All posts are presented here for informative, historical and educative purposes as applicable within fair use. NOTHING HERE IS FOR SALE !

Friday 5 April 2019

LG 42LH50 HOW TO CHECK POWER SUPPLY BOARD VOLTAGES - - LCD TV

HOW TO CHECK POWER SUPPLY BOARD VOLTAGES - LG42LH50 - LCD TV


POWER SUPPLY [SMPS] BOARD
MAIN PWB TO SMPS P-201 TURN-ON CIRCUIT
CLICK ON THE PICTURES TO MAGNIFY 
POWER SUPPLY PWB _ LOW-VOLTAGE TEST
AC Should not be applied at any time while adding resistors or while unplugging connectors as damage tothe circuit PWB may occur.
a) The SMPS PWB “MUST” be producing STBY 5V on all of the pins 7, 8, 9 or 10 (5V).  If 5V Standby is not being generated, the SMPS PWB is defective and must be replaced. There is no need to continue with the next test.
(b) Unplug P2400 on the Main PWB.
TEST 1:
(1) Add a 100Ωresistor between (5V STBY) pin 7, 8, 9 or 10 and Pin 2 (PWR). Apply AC. This will turn on the power supply.
a) Check that the 24V and 12V power supplies are turned on,
• P201 (24V pins 17 and 18)
• P201 (12V pins 13 and 14)
(2) Remove AC power.
POWER SUPPLY PWB _ BACK-LIGHTS TEST
P2400 Connector disconnected from the MainPWB. Apply AC after adding jumper.
Continue if the 1st test was OK. Leave original resistor in place.
(3) Add another 100Ωresistor between (5V) pin 7, 8, 9 or 10 and Pin 20 (INV On).
(4) Apply AC Power. Simulating a Power and Backlight On command.
Backlights Normal:
a) If normal, the backlights should turn on. SMPS OK.
Backlights Abnormal:
a) Recheck all connections.
b) Confirm the INV On/Off line pulling up to at least 3V.
REMOVE AC POWER:
c) Check the connections to the Backlights.
DO NOT check these when AC is applied as they carry 1200V each.
Note, either of the connections are unplugged, the backlights will not light.
POWER SUPPLY CONNECTOR-P201 VOLTAGE & DIODE CHECK
ADIM Pin 21 Fixed and not used.
PDIM Pin 24 can vary according to type of signal being processed and the OSD Backlight setting.
0.6V 0% to 3.3V 100%. Output from the video processor IC100.

Diode Mode values taken with all Connectors Removed.
Posted By: FRANK at 02:24
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