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Peabody <waybackNO584SPAM44@yahoo.com>: Jul 20 11:01PM -0500 Friends of mine have a Samsung 55" 4K TV, model UN55HU6840 (about 2014). They say they can hear audio, but the screen is black. I'd like to take a shot at fixing it for them since they don't really have the money to buy a new one. The encouraging thing is that until recently this has been an intermittent problem that's just gradually gotten worse, and now is permanent. But I'm encouraged to think it's not burned out LEDs, else it would never have been intermittent.   I just told you everything I know about repairing TVs, but am generally experienced in electronics as a hobbyist. Based on some Youtube videos it seems I should take off the back cover and check all the connections. Then I would go to the power board and check the voltages on the lines going to the backlight LEDs, and if low, start checking diodes and electrolytics, and of course look for bad solder joints.   Does this sound like a reasonable approach? Is there a typical cause of this symptom?   I've had no luck finding a schematic. Does anyone know where I would find that?   Well, any guidance would be appreciated.

Jeff Liebermann <jeffl@cruzio.com>: Jul 20 09:45PM -0700 On Wed, 20 Jul 2022 23:01:11 -0500, Peabody   >Friends of mine have a Samsung 55" 4K TV, model UN55HU6840 (about 2014). >They say they can hear audio, but the screen is black.   Have your friend turn on the TV and pretend that it has video. Make sure he can hear the audio that goes with the video. Have him take a flashlight and illuminate an area where you know there should be a picture. No movies with dark scenes please. Have him move the flashlight around and try different angles and room lighting. If he sees anything that looks like a faint image on the screen, then the TV has an backlighting problem. That model uses LED edge lighting, so look for problems in that area. If he doesn't see anything with the flashlight, then it's a video problem. Your approach is ok, but without a service manual and a schematic, repairing a PCB might be problematic. Think about isolating the problem to a particular PCB and order a used replacement from the cannibals on eBay.   -- Jeff Liebermann jeffl@cruzio.com PO Box 272 http://www.LearnByDestroying.com Ben Lomond CA 95005-0272 Skype: JeffLiebermann AE6KS 831-336-2558

Peabody <waybackNO584SPAM44@yahoo.com>: Jul 21 10:10AM -0500 Jeff Liebermann says...   > schematic, repairing a PCB might be problematic. Think > about isolating the problem to a particular PCB and > order a used replacement from the cannibals on eBay.   They've already taken it down and put it in the garage, so I'll have to do the flashlight test when they bring it to me. But I have a little more information.   This happened before, about three years ago, and they spent $250 at a local repair shop, which replaced one of the boards. But they don't know which board, and don't have the paperwork that might tell. But they say the symptoms are the same.   I found a repair video of this exact model:   https://www.youtube.com/watch?v=nhFnoLILlG4   which turned out to be bad electrolytics. I haven't done a lot of repairs, but so far pretty much all of them have been bad caps - usually high ESR. Most recently, that's two Disney coffee mug warmers and the power supply for my Ooma box. Anyway, what I'm hoping for is either a bad connection, or a bad solder joint, or some component on the power board that I can replace. I'm encouraged by the size of the components on that board - not all tiny 0201 smd, but through-hole stuff as God intended.   Well, I'm not sure anything will come of this, but I think it's worth giving it a shot. And working on stuff like this is my idea of a good time. But I would sure like to find the schematic   Film at 11.

Jeff Liebermann <jeffl@cruzio.com>: Jul 21 09:16AM -0700 On Thu, 21 Jul 2022 10:10:30 -0500, Peabody >boards. But they don't know which board, and don't have the >paperwork that might tell. But they say the symptoms are >the same.   You might be able to identify which PCB was replaced by inspecting the heads on the PCB mounting screws for wear caused by the screwdriver bit.   I don't know about your local repair shop. The lack of historical information sounds like they want you to bring the TV in for another repair instead of fixing it yourself.   In California, repair shops are required to keep records for 3 years. <https://bhgs.dca.ca.gov/laws/ear_regs.pdf> 9842. One copy shall be given to the customer and one copy shall be retained by the service dealer for a period of at least three years.   2764. Record Keeping - Customer-related Records A legible original or legible copy of the following records shall be retained by the service dealer for a period of at least three years: invoice, customer claim check, estimate records, and employee records.   If your friend paid sales tax on the parts, the shop has to keep records for 4 years.   Different states will have different rules and time periods.   -- Jeff Liebermann jeffl@cruzio.com PO Box 272 http://www.LearnByDestroying.com Ben Lomond CA 95005-0272 Skype: JeffLiebermann AE6KS 831-336-2558

"ohg...@gmail.com" <ohger1s@gmail.com>: Jul 21 09:17AM -0700 On Thursday, July 21, 2022 at 12:01:15 AM UTC-4, Peabody wrote:   > I've had no luck finding a schematic. Does anyone know where I would > find that?   > Well, any guidance would be appreciated.   The HU series *does* have intermittent issues with LEDs, either from individual LEDs or the interconnects on the strips. Sometimes you can change just the bad LEDs or hardwire the interconnects if there is a voltage drop across them, but the best option is to order the complete set of strips from someone like ShopJimmy.

Tim R <timothy42bach@gmail.com>: Jul 20 05:01PM -0700 I went to replace the AA in a kitchen timer and found it had leaked out of both ends.   I think I've had more of these leak in the past year or so than in the previous ten. Is there something different in manufacture, or am I just unlucky?   I usually take batteries out of stuff I won't need right away but they've been leaking in a plastic bag anyway.

danny burstein <dannyb@panix.com>: Jul 21 12:06AM >I went to replace the AA in a kitchen timer and found it had leaked out of both ends.   >I think I've had more of these leak in the past year or so than in the previous ten. Is there something different in manufacture, or am I just unlucky?   I noticed this starting about 15 years ago. The first time was with a bunch of Sears Die Hard branded AA's and D's.   A couple of years later I ran into this with name brand Duracell and Everready.   I suspect just about all these companies now just slap their label on "cheapest supplier of the week"...     -- _____________________________________________________ Knowledge may be power, but communications is the key dannyb@panix.com [to foil spammers, my address has been double rot-13 encoded]

Jeff Liebermann <jeffl@cruzio.com>: Jul 20 08:25PM -0700 On Wed, 20 Jul 2022 17:01:36 -0700 (PDT), Tim R   >I went to replace the AA in a kitchen timer and found it had leaked out of both ends. >I think I've had more of these leak in the past year or so than in the previous ten. Is there something different in manufacture, or am I just unlucky? >I usually take batteries out of stuff I won't need right away but they've been leaking in a plastic bag anyway.   These AAA alkaline cells were made in 2007. This is what they looked like in about 2016 or 2017: <http://www.learnbydestroying.com/jeffl/crud/Kirkland-AAA-leak.jpg> Not much has changed since then. I typically purchase batteries in lots of 50 or more. I've noticed that all the batteries from a single lot act much in the same way. In other words, they all leak at the same time. With some lots, I get lucky and they never leak. Others, like those in the photos, will leak while still in the bubble package. The SoC (state of charge) doesn't seem to matter. I'm finding almost discharged and unused batteries start to leak at the same time. Temperature does make a difference. Alkaline cells stored in the refrigerator (not freezer) last longer before they leak, but will eventually leak anyway.   Over the years, I've systematically removed alkaline batteries from my equipment and replaced them with whatever is appropriate. I've had good luck with Energizer Ultimate Lithium cells. They're expensive, but so it the equipment a leaky battery will ruin. <https://www.energizer.com/about-batteries/no-leaks-guarantee> <https://www.energizer.com/about-batteries/battery-leakage>   For most everything else, I've switched to either NiMH, LiIon, or LiPo rechargeable cells. For LiIon and LiPo, I install voltage dropping diodes, a regulator IC, or something to bring the voltage down to something that won't destroy the electronics. NiMH is close enough to alkaline cell voltage that it can be used without modification.   For 9V batteries, I use the 600ma-hr LiPo rechargeable replacements: <https://www.ebay.com/itm/124977792380> Quality sucks, prices have doubled to $8/ea, but long term cost of ownership is still much better than having alkaline batteries trash my equipment. Besides being rechargeable, they LiIon and LiPo will hold their charge for a long time. It's nice having an almost fully charged battery ready when I decide to use a rarely used piece of equipment.       -- Jeff Liebermann jeffl@cruzio.com PO Box 272 http://www.LearnByDestroying.com Ben Lomond CA 95005-0272 Skype: JeffLiebermann AE6KS 831-336-2558

Bill Gill <billnews2@cox.net>: Jul 21 08:24AM -0500 On 7/20/2022 7:01 PM, Tim R wrote: > I went to replace the AA in a kitchen timer and found it had leaked out of both ends.   > I think I've had more of these leak in the past year or so than in the previous ten. Is there something different in manufacture, or am I just unlucky?   > I usually take batteries out of stuff I won't need right away but they've been leaking in a plastic bag anyway. I have had bad luck with Duracell batteries. They seem to leak when used in items that are low usage. The emergency flashlight in my bedside table and the batteries in my thermostat for example. I have had to spend quite a bit of time, off and on, cleaning contacts when I used Duracell.   Now I always use Energizer batteries. I have never had any of them leak.   Bill

Charles Lucas <charlesandmilly@gmail.com>: Jul 20 06:53PM -0700 On Wednesday, July 20, 2022 at 9:39:02 AM UTC-5, Peter W. wrote:   > It is "Aim. Ready. FIRE!". Not "FIRE!, Ready, Aim. > Peter Wieck > Melrose Park, PA Thank you for everything, Peter, sir. I understand completely where you are coming from. I shall be more judicious in the future before I respond. I realize I was all over the place on this thread (along with noting and emphasizing particular things- just things to think about, as stated before). Thank you for everything. No harm or irritation intended. Thank you for teaching me a lot here. God Bless You. Have a wonderful day.   Sincerely,   Charles Lucas

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Jul 20 06:45PM -0400 Chris K-Man wrote:   > The point is, it's an issue, especially at certain parts of the AM dial, when a radio > is within 10 feet of the service mast outside my bathroom corner window. Outside > of the bathroom corner of the apt, the interference drops off exponentially.   "Doctor, doctor! It hurts when I go like this!"   "So don't go like that." ;)   Cheers   Phil Hobbs

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