Samsung LED TV UN55J6201FA

[jkb242]

This set has a BL issue for which all BL strips are on order. I need to isolate the BL issue once new LEDs are installed without the screen being connected to the TCON board. I do not want to reassemble the screen assembly until I know the BL works after replacement. Can I confirm BL operation without the TCON being connected? My plan is to monitor the BL for several minutes without the screen or TCON connected. Everything else about the set appears to be normal.

Thanks

[handsworth]

Re: Samsung LED TV UN55J6201FA

Disconnect the power supply from the main board. Plug the power supply into the ac outlet. The power supply will turn on the leds. Samsung tvs have this unique feature, but I cant recall why it does it.

[neilc6]

Re: Samsung LED TV UN55J6201FA

Yes Samsungs have pullup resistors on the control signals so you can test the backlight with the main board disconnected.

For other models, TVs will typically turn on with the panel disconnected. I always check the backlights before reassembly and again with the diffuser sheets replaced to check for any trapped dirt or dust or unevenness.

[jkb242]

Re: Samsung LED TV UN55J6201FA

Thanks for the advice. I wanted to keep the initial thread brief without going into certain steps I took when investigating the no BL issue. Simply to share what I did next in troubleshooting the strips I’ll add here for an benefit to the forum, hopefully.
Prior to opening the set I used a bright light to check for any display info and determined it was working but that’s about it whether partial screen or not that wasn’t my main concern at that point. Once I found the strips had several burned out LEDS, I decided to repair the strips since I am equipped to do and have done lots of SMD repairs. So I replaced about 15 of the 70 LEDs on 5 strips. When completed, I started the set without the TCON or screen attached and got a couple of flashes then no BL again. Furthering test showed many of the LEDs I replaced were defective again. Inferior 3v replacement LEDs? Wasn’t positive of that either. Then decided I would order a full set of working strips for this model. I did not have an LED set checker originally, so I tested each half strip separately using 20vdc with current limiting set to 500ma. All strips look fine but in the set, no joy. I concluded the issue was due to some connections inside the strips. Have not received the replacement strips yet but wanted to be sure that operation without the TCON or screen attached should allow normal BL operation before reassembling. Voltage 285vdc at LED driver connector and all series jumpers on the power supply board were solid. Hope this is beneficial to others.