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Samsung UN55C6400RF No Power

Model UN55C6400 UN55C6400RF UN55C6400RFXZC

This TV did not turn on and would click every few seconds.

This youtube video indicates to check for shorts on transistors for the LED drivers on the power supply board.

Power supply board is BN44-00358B.  Schematic is available online here

There are 4 transistors Q9101, Q9104, Q9201 & Q9204 and I found one shorted and previously replaced. I ordered replacements on Digikey part#FQU5N40TU-ND (Mosfet N-CH 400V 3.4A Ipak) and replaced all four proactively.

This board may also have an issue with blown fuses which means you should check QP801, QP802 and CP808 for shorts.

After replacing the transistors, the TV powered up but one side was dim.  This was traced to loose connections on the LED connector.

Update:  The TV came back with a dim side again which I suspected was a power supply fault.  I ended up buying a compatible substitute board from the Chinese company which ended up fixing the problem.

Sony KDL-55EX620 Won’t Turn On 2 Blinks

This TV was flashing a 2 blink code which is a power supply error.

A service and training manual can be found here.

Power supply board part number is APS-299 (1-474-303-11 147430311).  Searching on ebay found repair services and repair kits for this board.

Posts on badcaps indicated potential shorted transistors Q6101, Q6102 and open resistor R6540.  When i tested these parts, all three had failed.

Q6101 and Q6102 are shown in the schematic as TK5A50D.  These are 500V, 5A N-Channel MOSFETS.  I had FDPF7N50U (Digikey #FDPF7N50U-G-ND) spares from a previous repair.  R6540 is listed as a 0.1 ohm 1/2W resistor and I temporarily substituted the part with a 0.47 ohm 1/2W fusible resistor I also had.  Digikey substitute would be 0.1DMCT-ND (0.1 ohm, 2W fusible).

With these 3 components replaced, the TV powered up.  This failure is similar to a previous repair on a Sony KDL-46EX400  here.

This video describes repair of a 2 blink code on a KDL-46EX523.  The boards are very similar but the designators and transistors are different.


LG 47LM4600 Turns On No Backlight

The front standby LED was on and would turn off and on when the power button was pressed but there was no backlight and no sound.

Probing the power supply connector, PWR_ON and DRV_ON signals were being sent from the main board but there were no voltages on the LED connector or secondary voltages like 12V.  Checking the big main filter capacitor across the leads, the PFC circuit was not boosting up to the expected 390VDC.  Power supply part number is EAY62512701.

Posts on badcaps suggested checking D607, C603, Q601 and Q602.  I found D607 shorted while the other parts testing good.  I ordered a replacement for MUR460AX (600V, 4A axial leaded diode) from Digkey part #MUR460GOS-ND

Normally, the diode in this application is a TO-220 package which can be mounted on a heatsink for better heat dissipation.  When I installed the new part, I floated it above the board to allow for more airflow around it.

With D607 replaced, the TV powered up with backlight coming on.  The interior of the TV had black dust on the power supply board and back of the TV and I confirmed that the owner was a heavy smoker.  There was also some smoke residue on the bottom corners of the TV.


Panasonic TC-L32C22 Won’t Turn On

This TV attempted to turn on but there was no backlight.  It was probably flashing a diagnostic blink code (possibly 10 blinks) but the front LED was out.

A service manual with all schematics is downloadable from here.  Power supply part number is TNPA5123CA.

Checking the voltages at the power supply connector, standby voltages at TUNER6V and VSB were present and stable at 6VDC.  With the power button pressed, 6V appears at RELAY and 2.3V on TV_SUB_ON which turns on the PFC circuit supplying DTV12V and 17V and 32V.  These voltages drop when turned on indicating an error condition was causing a shutdown.

Checking the main filter capacitor, I measured 390VDC on it when the TV was briefly on.   To force the power supply to stay on, I disconnected the connector to the main board and applied 6V to the RELAY pin and used a 10K external resistor from VSB to TV_SUB_ON.  With the PS on, the 390VDC stayed on but DTV12V and 17V was still shutting down.  This lead me to suspect IC7301 (SSC9512).  I measured  R7303, R7305 and R7306 by lifting one leg up.  R7306 measured a bit high – 1.3M instead of 1M so I replaced it and the TV powered up.

I still had the problem of no front LED and this was traced to a broken connector on the cable connecting to the main board.  I had to test and wire all the lines from the IR/LED board to test points on the main board  to bypass any bad connections.

Element ELEFT407 Won’t Turn On Has Standby Light

This TV had a standby light but wouldn’t turn on.  I tried freeze spray on the eeprom (UF1) but it didn’t work.  I still suspected eeprom failure however.

The TV uses the same chassis and all-in-one board from many budget TV brands like RCA,  Westinghouse, and Emerson.  I have also seen this chassis on a newer LG TV.

Shopjimmy indicates there are two different main boards with two incompatible eeproms.  One is for serial numbers starting with G1400 and the other is for J1400.  I checked ebay and there was a seller selling preprogrammed eeproms for $10 USD vs $15 USD that shopjimmy was charging.  I am still waiting for my CH341A programmer so I ordered the cheaper one.

Once installed, the TV powered up.

Samsung UN46F6300AF Won’t Turn On Dark Areas

Model UN46F6300 UN46F6300AF UN46F6300AFXZC

Power supply board number BN44-00611D

This TV would attempt to turn on but there was no picture or backlights, just a blinking front LED.  With the back panel off, I disconnected the cable between the main and power supply boards and the backlights did not come on.  Suspecting bad LED backlights, I carefully took the LCD panel off and tested all the LED strips with my LED tester.  All the strips tested good.  Measuring the PFC voltage across the leads of the big capacitor, I was only getting 270V instead of the expected 390VDC.  I stumbled on a post on badcaps indicating a low VCC on ICP801 caused by a high RS802 is a suspect for low PFC voltage.  Measuring RS802, it was much higher than the expected 10 ohm value so I replaced it with an 0805 resistor I had.  With the new resistor, the TV powered up.  However, the top part of the screen was dark and it looked like the top strips weren’t getting any power.  I found poor connectivity on the connector from the strips to the main board and had to bypass the connector on several pins.  With this last fix, the TV powered up with all the backlights running.  I did find the connector on the LED side  a bit flakey as well and the backlights went out when I pushed on it.

Emerson LF391EM4 No Power No Standby

This TV was dead with no standby light and no power.  A service manual is available for download here.

The power supply board has jumpers as test points.  I measured 20VDC P-ON+21V and 0V on AMP+13V.  AMP+13V provides power to the main board.  There is a FET which could short and blow a fuse but the 20VDC reading indicates the fuse is ok.  Checking the resistance of AMP+13V to GND with the board alone, I measured a short.

In the service manual, there is a flowchart for this line.  AMP+13V is not output.  No-> Check D653, D655, C654, C655, C668 and their periphery circuit. Repair it if defective.

Pulled off C654 and C655 and they both tested good.  I lifted one leg of both of the diodes and D653 was shorted.  The part number is SB3A0BH which is a 100V, 3A Schottky diode.  Equivalent substitute at Digikey is SB3100 (641-1418-1-ND).

I replaced both diodes and TV powered up.  Luckily, there was no damage to other parts when the diode shorted.


Ryobi One+ Replacement Batteries

After my battery ran out on my Ryobi drill, I decided I should get a second spare to swap out.  I had purchase a kit including drill, circular saw and flashlight many years ago and it has been reliable though not heavily used.  When using the saw, I have to constantly swap the single battery with the drill so another reason to get a second one.

Genuine and new batteries are pretty expensive.  There are many third party and refurbished batteries available on ebay.

My drill uses battery model P103 (28WH, 1500maH  – some are 24WH, 1300mAH).  I found a seller selling refurbished P102 (24WH, 1300maH) and P107 on ebay (28WH, 1500maH).  I assuming they install new cells into old cases.  I ordered a P102 for around $20 USD and will update once I get it in and test it for a bit.  Lithium batteries can pose a fire hazard so I am wary with third party versions.  They also can only be shipped surface mail.

This site here compares Ryobi battery models.

Haier 40D3505 Won’t Turn On

This fairly new TV had an issue where it wouldn’t turn on.  Searching on ebay for this model, I found a preprogrammed eeprom from shopjimmy which suggests this model may suffer from eeprom failures.  To test if the eeprom is at fault, I cooled it with a can of inverted duster spray with the tv unplugged.  Plugging it in, the tv turned on.  The faulty IC is located beside the main processor and placed at an angle (UF1 designator). The part number is 25L3206E.  I ordered the part from Shopjimmy on ebay, replaced it and TV is working.

For future repairs, I have ordered a cheap USB eeprom programmer on ebay (search CH341A).  This has a DIP socket but surface mount SOP8 adapters are available.  They come in two widths – narrow is for 150 mil wide chips and wide is for 200 mil.  The IC for this TV is a wide version.


UN40EH5300F Reboots On Its Own Can’t Connect To Internet

Model numbers UN40EH5300F UN40EH5300F  UN40EH5300FXZC

This TV would reboot on it’s own after a few minutes.  Badcaps posts indicate possible failure of the wifi module.  When I went into the network settings, it froze the firmware and it could only be reset by unplugging the TV,  I had a WIDT20R BN 59-01148B module from a scrapped TV so I replaced it.   The TV no longer rebooted but it couldn’t find any wireless networks when I ran the setup.  Used modules on ebay are around $50-$60 USD but I was able to find compatible ones on Aliexpress for under $20.  My parents UN46ES6100F has the same issue (can’t find networks) so I ordered two.

With a new module installed, the TV was able to find available networks.  I did have an issue since it could connect to my router but couldn’t connect to the internet.   It appeared that the IP Setting for DNS was set to manual, so once I changed it to automatic, it connected.

Update: The wifi module in my parents TV failed again and it can’t find any networks which was the original problem.  Not sure if the fault is in the main board but not likely to replace it again.