Re: Samsung LN40B640R3F -- standby voltage slowly drops/drains to zero
Update: Took my TV to a repairman and he had a good power/inverter board that solved the problem. Simple board replacement -- 40 bucks. Still curious as to what specific components were faulty.
pjs2015
Member
Last Activity: 08-18-2017, 04:16 PM
Joined: 01-09-2016
Location: Clayton, NC
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Re: Samsung LN40B640R3F -- standby voltage slowly drops/drains to zero
Yeah I see what you are saying. Not sure what was meant then. I was thinking about replacing the diodes, but I wasn't able to verify if they were defective. There's a TV repairman that I'm going to be taking it to, who will look at it for a low price. I'll post back if he finds anything....Leave a comment:
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Re: Samsung LN40B640R3F -- standby voltage slowly drops/drains to zero
Here's a picture of them that I made, corresponding to the circles from the schematic as well as an arrow showing which pin is the emitter on QB801. I haven't gone any further with it. I was going to try to replace those components but haven't gotten around to it....Leave a comment:
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Re: Samsung LN40B640R3F -- standby voltage slowly drops/drains to zero
Aw crap. Ignore my previous post then. The one I was testing isn't one of the ones that are circled. I guess what I was seeing was normal then. Thought it was supposed to hold the voltage. I see those circled ones on my board. Thanks for the diagram! Huge help! I will check what you said bud. Appreciate the help!...Leave a comment:
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Re: Samsung LN40B640R3F -- standby voltage slowly drops/drains to zero
Wow, I took out one of what I think are the zeners you are talking about and it does appear to be leaky. The zener is at ZM803 on the board in series with ZM805. They are both 12V 1N4742A zeners. When I hooked it up to a test circuit, it was at 12.13V. Couple hours later, it's now at 12.22V and still rising. Seems consistant with my issue. Thanks tom66!...Leave a comment:
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Re: Samsung LN40B640R3F -- standby voltage slowly drops/drains to zero
Moreno, yep that's how it is connected. The time on depends on the time unplugged, strangely enough. For example, if I have it unplugged for a week it, then plug it in and turn on, will stay on for hours, but after it goes off, it won't come back on (and no standby light) unless I unplug it for another period of time. I will try the hair dryer. Thanks for the suggestion.
EDIT: Actually I have to leave it unplugged for a while before trying the hair dryer because I had it plugged in...Last edited by pjs2015; 01-09-2016, 06:49 PM.Leave a comment:
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Re: Samsung LN40B640R3F -- standby voltage slowly drops/drains to zero
Hey, thanks for the reply! Was yours intermittent in that sometimes it would work and other times not, or like mine? In my case, it's actually reliable in that if I leave it unplugged for a while, then plug it in, the TV will turn on, but then the voltage drops and then the TV turns off. So, not sure if that would be intermittent or not....Leave a comment:
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Samsung LN40B640R3F -- standby voltage slowly drops/drains to zero
I've been having a strange issue that I've haven't seen in the searches I've done. I have a Samsung LN40B640R3F which has a BN44-00264A power supply/inverter board which I think is the problem. If I turn the TV on, it works, but then eventually goes off after a few minutes. Then it won't come on again unless I unplug it for a while.
I checked the standby voltage after I've left it unplugged for a while and then turned it on, and the voltage starts normal and then slowly drops to zero.
Could this be a simple capacitor problem? I visually checked them and they all... -
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Love this site! Thanks to all who participate! I've gotten a lot of great info from here.Leave a comment:
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