Recent content by HMark

Thought I should type a final post to close out this thread. To recap, I took in a 48" Samsung with no picture or sound for a friend. After attempting a hard reset with the external power switch, the LED light would blink 6 times indicating a switch mode power supply (SMPS) problem. After some...

Thanks for your responses. I've been under the weather (cold) since last Friday and haven't worked on the Toshiba flat-screen again until this morning. Yes, one of my meters measures true RMS. I haven't measured switching noise on the unloaded output of the power supply yet, but I should do...

I had a typo in my response just now. The new LED string just fires (minimum brightness) at 85 VDC, but at 26 milliamperes, not 85 ma.

Hi, thanks for your reply and suggestions. I haven't repaired a television since the mid 1970's and they have obviously changed a great deal since then. I'm attempting to repair a 48" Samsung for a friend, recently widowed, who can't afford a new one. I do some repair work now that I'm retired...

I'm posting an update to my own post. I'm now reasonably sure that the switch mode power supply (SMPS), when working properly, provides current limiting to power the LED strips. Just to be sure, however, I've calculated that the entire string (at minimum LED firing voltage) should require 85.2...

Samsung 48" PS and LED issues Hi: I'm new to the forum but not to electronics. I'm a retired RF engineer with over 50 years in broadband telecom and video delivery. I took in a 48" Samsung TV (recent model) to see if I could repair it for a friend. No picture or sound. The red power LED light...