Samsung forum: LN52A750 (52" LCD) clicks on & off continuously

Mine started two days ago without warning. Checked board and no evidence of a damaged capacitor. If you learn of anything please let me know.

Thanks,

Alan

Chatted with Samsung this morning and they agreed to have all the capacitors replaced. Not sure if this will remedy the problem as the capacitors appear to be in good working order.

Alan

I did take the offer but I am VERY skeptical.


Alan

Hey Daddyblue252,

Did the cap replacement fix your problem? I ask because two days ago my LN52A750 (purchased 8/2008) did the exact same thing! It worked flawlessly for three years. Powered it off and the next time it was turned on, it began cycling on/off automatically any time the cord is plugged into the wall. I tired unplugging it for 30 minutes, but again cycles when plugged in. It comes on with the red LED flashing, plays the Samsung power-up tune, backlight turns on, but no picture. It stays on for about 10 seconds and then abruptly turns off like cutting the power and then immediately trys to power on again...It does this over and over...

My caps look OK (no bulging) or admornal appearance. I have two 1000uF@25V , twp 1000uF@16V, and two 470uF@25V types, but some of the 1000uF measure a bit low with an LCR meter (905uF @ 100Hz test). The 470uF measure 450uF@100Hz.

The Samsung service tech is coming to my home 12/1/2011 to replace the caps free of charge as part of a one time service. I have a feeling the caps are not my problem, maybe the main board worst case....what was your end fix?

Carl

mery64 -


The service manual can be found here:
http://www.samsungparts.com/Products/Parts_and_Accessories/PID-SM-LN52A750R1F.aspx?model=LN52A750R1F

--HDTech

Online Brand Ambassador

- Click here to visit the Samsung forum
- Click here to visit the Samsung store on CNET

amery64 -

I don't know. You'd have to inquire with someone at www.samsungparts.com

I have no idea what you would have downloaded.

--HDTech

Online Brand Ambassador

- Click here to visit the Samsung forum
- Click here to visit the Samsung store on CNET

I haven't had time to update this post until now, so I thought I would catch everyone up. While the Samsung Technician was at my home 2011-11-30 for the capacitor procedure, he replaced ONLY the four 1000uF with new capacitors and reinstalled all the other caps I had removed and tested. That's right, instead of installing new capacitors, he put back the old ones. Before he replaced the 1000uFs, he had me sign an electronic form stating I would be responsible for all further repairs (parts & labor) related to this problem if the capacitors do not fix it. Hmmm, that was strange, but I had to sign it. Not a problem for me since I could get the main board for ~$130 online with a 6 month warranty from 2 or 3 online stores when it was in stock (...popular item). What about the poor sap that had to pay $500.00 for the Samsung repair!

The tech left and I sat with my broken TV and my schematic determined to troubleshoot the cause. Over the next week I solder tacked 19 small wires on key signals and voltages. Armed with a multimeter, oscilloscope, and a 16 channel logic analyzer I zeroed in on one IC that controlled the power sequencing and reset. It was apparent that the heart of the main board is a small micro controller (MICOM) WT61P6S combined with a 2K AT24C02 Atmel serial EEPROM which controls the following:
+ power-on/off
+ monitors voltage levels
+ IR remote and perimeter touch buttons
+ communicates with two main processors (A1F & A1B) over a simple UART
+ Issues reset signals to the main processors and other system.
+ Audio control
+ HDMI Identifier

What I discovered was that all the voltages were all within normal limits including those on the main processors. The DDR memory on the two processors was active and appeared to be functioning fine and all clock signals were stable and active. What I found strange was that the watchdog timer in the MICOM was timing out every 29.4 seconds, turn off for 5 seconds, and then turn back on for another 29.4 seconds. On the oscilloscope, you could see the SW_POWER (turns on & off TV) signal pin on the MICOM (PD1) go Hi-Z briefly (mid-rail voltage) and then get configured as an output to drive the signal at full voltage for another 29.4 seconds. All I had to do was plug the TV in and it started cycling on and off automatically.

I measured and /or disabled all other signals from the MICOM one by one to isolate the cause. The last suspect was the MICOM code. What I determined was that the firmware in the AT24C02 seriel EEPROM was somehow corrupted or bad data written to the EEPROM caused the MICOM to enter an undefined state which eventually caused it to time out (no watchdog kick) and reset. When I ground the clock signal to the EEPROM, the TV will not start at all, but during the 29 seconds, I see plenty of data between the EEPROM and MICOM. Again, all other circuits appeared and measured normal. No overheating ICs or bad or missing clock signals.

In any case, I was now convinced that this was a software problem caused by my son powering off the TV off while the Blu-ray was playing which may have caused the AnyNet+ feature to write (or not write) incorrect data to non-volatile memory. When my wife turned the TV back on an hour later, it would play the Samsung startup melody, would not power up fully (black screen w/ backlight), and began cycling.....over and over.

While I was waiting for one of the three on-line vendors (ie. shoppjimmy.com, rivervalleyelectronics.net) to get the main board back in stock, I surfed around on Samsung's own web site and stumbled upon a very important tip in the "Troubleshooting Guide" for my specific TV titled:

"LN52A750R1F TV Turns Off and On Continuously"
In it they described my issue exactly and recommended a firmware update that was released October 2008 to resolve the issue. I purchased my TV August 2008 (built in June '08). The last paragraph said "If your TV is turning on and off continuously and you are unable to install the firmware then your TV WILL REQUIRE SERVICE to resolve the issue". Basically Samsung is acknowledging that there is a software problem causing the On/Off cycling which needs the new firmware to correct. If you can't power up the TV, you can't load the firmware through the USB port on the TV. This to me amounts to a Samsung-admitted RECALL to change the main board free of charge!

On December 7th 2011, I picked up the phone a called Samsung customer service and explained that the service tech came out 11/30 and replaced the capacitors, and also mentioned the Troubleshoot Guide firmware issue I found on the Samsung web site. He responded by insisting that the web site I was looking at was a third party site, not the Samsung official site. He then reminded me that I had signed the form accepting all financial responsibility for repairs other than the capacitors for this power on/off cycling problem. I offered to send him the web link and even offered to guide him to it so he could verify it himself. He flat out refused to let me show him and stood firm. I'm now PO'ed so I got forceful and said I didn't care what I signed and that Samsung basically admitted the firmware problem so they should fix my TV for free as a recall for this obvious design flaw. It was dead quiet for a few seconds, then I said "you obviously aren't going to help so I need to talk to someone who can - your manager" He put me on hold for 5 minutes and then came back and said Samsung would activate a warranty window (parts and labor) to fix my TV free of charge.

December 21st, 2011, the Samsung repair tech replaced the main board like I expected and the TV worked fine. I removed all the wires on the old board and he took it with him. No doubt, Samsung will probably slap it in a test fixture and directly reprogram the 2k EEPROM using the factory test points on the PCB and it will work fine again....for someone else's TV...with the same issue! I'm just glad I got it fixed for free, but I had to fall back to my 22" TV for almost a month. Surprisingly, the firmware in the new main board is newer (higher # = 1014.0, 2009-05-22) than the downloadable upgrade from Samsung's web site (October 2008 release 1012.2) so you know they still needed to tweak for other issues...

Now we have both hardware and software contributing to defective stuff. Consider if all electronics have software running them, what percentage of failures are just bad software code instead of an actual hardware failures. If it's any conciliation, Samsung settled its class action law suit on February 23rd 2012. It seems they agreed to fix all TVs purchased before December 31st 2008 and give up to $300 to each TV owner experiencing power cycling problem. Hey, where is my $300 bucks...for pain (dealing with Samsung customer service), suffering (no TV), and compensation for my troubleshooting abilities!

Conclusion:
If you have an LN52A750 (or 40, 46) with a manufacturers date in 2008, turn off the Anynet+ feature IMMEDIATELY or risk ending up in my situation. You will just have to change the input source with the remote instead of automatic source switching. My profession and abilities armed me with facts to build a case for a free repair. Most of you would be stuck with a $130 to $500 repair bill for a TV you bought 3 years ago for $2200!

Good Luck!

Hello newmytitanic, and anyone else out there who wants to weigh in on this.

I have a Samsung 46"(model 4665) that I purchased about 4 years ago. It first began with a pixel problem about 6 months ago. There would be some spots on the screen when it was truned on, but a simple off/on and they would clear up, usually with just one off/on. Then at about the same time I noticed that some times it would click on/off, like it was trying to come on, then it would come on the 2nd time. Now it has just begun taking 3 times of clicking, before it comes on.

My question is, has anyone had any luck with getting Samsung to pay for it. I noticed that newmytitanic said they honored their "extended" warrenty. I did not purchase an extended warrenty, so does that mean that Samsung will do nothing? Is there a good number to call to get any response from Samsung?

I've read were people have replaced capacitors, but that sounds pretty tough to do. I may try that when the TV doesn't come on at all.

I've read where it can cost as much as $400.00 for a tech to "fix" the problem(new power supply, motherboard?). That may not be worth it when you can buy the same, or better TV now for $1000.00 or less.

Any thoughts, advice, help, is greatly appreciated.

Kevin

Repeating my info from previous entry:

I have a Samsung 46"(model 4665) that I purchased about 4 years ago. It
first began with a pixel problem about 6 months ago. There would be some
spots on the screen when it was truned on, but a simple off/on and they
would clear up, usually with just one off/on. Then at about the same
time I noticed that some times it would click on/off, like it was trying
to come on, then it would come on the 2nd time. Now it has just begun
taking 3 times of clicking, before it comes on.

New:

After calling a couple of local(San Luis Obispo area) service shops, I took it into a place that I felt knew the problem best after talking to them on the phone. They ended up replacing all 4 capacitors on the power supply with slightly more powerful ones(?), and also re-soldering the light inverters. It cost $140.00. It seems to have fixed the issues, although I've only used it for about 2 days so far. It comes on the first time, with no pixel issue.

Thanks for all the information on this forum. I felt like I had a good idea about the problem and what it would take to fix it. I even thought about doing in myself after reading some of the how-to posts out there. I figured I should play it safe this time and get a professional to do it while the TV still had some more good years in it.

Kevin

The only reason Samsung was so gracious as to repair you TV is because they got sued for making faulty products. For reasons unknown, the class action lawsuit they settled was limited to TV's manufactured prior to 1/1/2009. My LN52A750R1XZA had the exact same capacitor problem identified in the lawsuit and Samsung refused to pay for the repair. I had to eat the cost myself. Their customer support kept telling me they COULD NOT make the repair because it was not covered under the lawsuit. No, that just means you DO NOT HAVE to make the repair so they refused. I climbed as many heads in customer support as I could and got the same response. They only made these TV's for maybe the first half of 2009, but probably only for another 3 months. Mine was manufactured in March 2009 with the same crap capacitors (I actually think the specs were wrong) so they failed (bulged) and my TV starting doing the on-off dance. They sent repair guys out quickly and the repair was taken care of for $130 bucks so the cost was not that bad, but I will NEVER BUY A SAMSUNG PRODUCT AGAIN. I made the point repeatedly to them that they will lose more than $130 by losing me as a customer (anyone want to buy a Samsung cell phone). For all you Apple haters out there, this is why I am a loyal Apple customer. Similar situation: my 2008 Macbook Pro had a bad NVIDIA video card soldered into the motherboard. It was out of warranty, but rather than losing a class action lawsuit, Apple just fixed it and kept me as a customer. I guess that's why Apple is not making any money these days.

Samsung just lost the lawsuit for the 10V rated capacitors they put on 12V powerboard. The capacitors ramp up the current to turn on the TV, and rated too low, eventually fail. It's for certain models.
Go to
www.samsung.com/capacitorsettlement, or 888-899-7602
You may be able to get the TV repaired for free.
The clicking is the retry on the power board after it fails. It will continually try to turn on, but the capacitors have trouble supplying the required voltage. To check yourself, remove the back, you'll see bad capacitor tops bowed upward, maybe some black tar leaking also. They'll be labeled 10V on a 12V rated board.

This is for everybody in this thread. I have this exact same model. unfortunetely with a cracked screen.have been tryin to look for a replacement screen. cant find anything. so if anyone is interested i can sell you parts for this tv. message me or comment .. and i will post parts on ebay. PAYPAL only please.

Thanks for reading.