Re: Samsung LN40B540P8F LCD Backlight Problems

Just a quick note, the bad transformer was a white one. There was no evidence of discoloring or overheating. There was only a difference in the resistance readings on the secondary coils, 1.1K versus 950.

Time will tell if there is a bad bulb that was the root cause of the failure. From what I have read this is a weak component that does not hold up over time. The set that I have is very lightly used.

Re: Samsung LN40B540P8F LCD Backlight Problems

Interesting enough I said to heck with it and installed the part even though I was not seeing 13 ohms (saw 10.6 ohms) on the primary or 1.1K on the secondaries (850 ohm on both) and the damned thing worked!

I am not an electrical guy so it is a mystery. I told ShopJimmy about my observations that the resistances did not seem right and asked for some specification of what they were supposed to be. They said they did not have any. I am a bit mystified by the whole TV repair business. I do not understand how you can fix these...

Re: TCL 55S401 LED LCD TV no backlight

Sorry, wrong thread again. Geeze, sorry.

Re: Samsung LN40B540P8F LCD Backlight Problems

I pulled the transformer that had a reading of 950 ohms on one of the secondary coils and ordered a new one.

Before installing the new one I checked the resistance on the primary and it was 10.6 ohms. The secondary coils were at about 850 ohms.

My understanding is that the primary should be around 13 ohms and the secondaries at 1.1K ohms.

Do you suppose that I received a defective unit?

Should I ask for another one to be sent?

This is the one that I purchased from ShopJimmy...

Re: TCL 55S401 LED LCD TV no backlight

Posted on wrong thread. Please delete this as I cannot find the option to delete it myself.

Re: Samsung LN40B540P8F LCD Backlight Problems



Must they be removed to check the resistance in the primary and secondary coils?

Thanks....

I have the symptom where the backlight is cycling. I have read other threads about various problems with transformers and MOSFETs and have a few questions.

A bit of background on the TV is that it was used very little and that is why I was considering trying to repair it. It was plugged in and not being used when a nearby lightning strike took out a 60" plasma, cable box, receiver, and other small devices (+ $2K in lost electronics). I suspect that this strike also damaged this TV but I cannot determine how badly. It was several days later that the backlight started cycling and...

Re: New Members - please post your introductions here

Hi, software guy here looking to repair my 40" Samsung LCD.

What could possibly go wrong with a software guy trying to dabble in electronics?

I am just dangerous enough to use a multimeter and safe enough to avoid high voltage circuits.

Brighton, Michigan.