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3 flashing lights, bad power board?

Posted: Thu Aug 13, 2015 9:16 pm
by Xtrattitude4u
Hi all,



Have a Samsung HLS6187W with intermittent 3 flashing lights issue.

Replaced the lamp with OEM phillips lamp twice (to ensure I didn't get a bad lamp)

Replaced Color wheel just to be thorough.



Noticed when the TV shuts itself down, or sometimes when powering on , I could hear a buzzing sound in the back.

Pulled rear panel off and shorted the Lamp door switch with a paperclip, found the buzzing noise was the lamp arcing but not lighting, then it may light or it might not.

At this point I'm convinced it's the ballast, so ordered a brand new one from Discount Merchant.



Unbelievably, the issue continued after replacing the ballast.



The tv usually shuts down after about 5 seconds of being turned on, and power cycling it a few times seems to warm it up enough that the issue goes away.

After it settles down it will stay on for hours, or all day without any issues. occasionally it will shut itself down later, but not very often.



The only thing left to replace I can think of is the DMD board or the Power board.

I'm leaning toward the power board, as I cant see how the DMD would cause the ballast to arc the lamp, but not provide enough power to light it.



I also have a symptom that has happened a few times, where while it is cycling on and off trying to light the lamp, the lamp will light but there will be no picture (or menu) until I turn the tv off and back on again. This was leading me to believe it could be the DMD, but that could be also caused by the DMD not getting enough power?



Does anyone know what voltage should be present at the power connector to the ballast?



Thanks for any help.

Re: 3 flashing lights, bad power board?

Posted: Sat Aug 15, 2015 1:05 am
by ChubbsTech
Hello,



The issue certainly sounds like the ballast board although you say you purchased one already. I am leaning towards the ballast maybe not performing as it should. Keep in mind that the power supply could be not providing the proper voltage to the ballast. Please give me a couple days and I will provide the information as to what voltage should be going to the ballast from the power supply. Keep in mind that the voltage from the ballast to the lamp is real high that a regular meter will not help you. I apologize for not having the information as far as voltage to ballast but I will Post more information shortly. For now have a good day be on the lookout for a Post regarding your issue.

Re: 3 flashing lights, bad power board?

Posted: Sat Aug 22, 2015 5:12 pm
by Xtrattitude4u
So I think it's the power supply at this point.



I pulled the power board out and immediately noticed there is a scorched area around a group of 3 resistors, and the general condition around the area underneath the board is poor at best.



I also have a new symptom, where before the unit shuts down, several random white pixels will appear on the screen, which is indicative of a bad DMD chip.

However, this only happens when the problem is occurring, so I believe the DMD is fine.



It makes sense that several separate components would show signs of failing if they were all not receiving the correct voltage.



I would think if the resistors were failing, they would be allowing more voltage to pass than intended.

Would the lamp also not light if too much voltage were supplied to it?



I referred to the service manual and the resistors are listed as 6.9K Ohm, 2Watt with 5% tolerance.



I think I'm going to remove them from the board and test them today, since I don't yet know what voltage should be present at the Ballast connector.



Please let me know if anyone knows what voltage should be present, as the service manual doesn't seem to list that.

I remember seeing the info online somewhere but can't find it now.

Re: 3 flashing lights, bad power board?

Posted: Sat Aug 22, 2015 6:50 pm
by Xtrattitude4u
I pulled the resistors off the board and I guess they are 68k Ohm, not 6.8.

They tested all within spec, between 68.2-68.5k ohms.



I desoldered/resoldered them onto the board, and carefully inspected the rest of the board.

No swollen caps or any other sign of damage.



Re-installed the board and the issue continued.



I'm kind of torn right now as I'm kind of out of ideas.



The only reason I don't think it's the DMD is the lamp arcing but not lighting.

As I understand, the DMD sends a 5v signal to the power board to power the ballast, but the power board is what provides the voltage.

I don't see how the DMD could cause the ballast to arc the lamp, but not light it.



Please correct me if I'm wrong here.

Re: 3 flashing lights, bad power board?

Posted: Sat Aug 22, 2015 11:31 pm
by Xtrattitude4u
So I connected a multimeter to the pins on the power board and it is maintaining 308-309 volts while on. When it shuts itself off and the lamp starts arcing and buzzing it will rise to 315 - 320 and then drop to around 10 after the tv shuts down.



This seems like normal operation to me.



Any ideas?

Re: 3 flashing lights, bad power board?

Posted: Tue Aug 25, 2015 12:43 am
by ChubbsTech
Hello,



I looked into this and from what I was able to find out is that on average there should be 350 volts going to the ballast. It sounds like you are under that. This makes me believe that the power supply could be the problem. I hope this helps you some. Remember we are here to assist so don't hesitate to ask further questions.



Best Regards,

Re: 3 flashing lights, bad power board?

Posted: Fri Aug 28, 2015 6:34 pm
by Xtrattitude4u
Well, I've been looking for the power supply but it seems no one carries it anymore.

If I cant find it then my only option left would be to try to test/replace comonents on the board.

I don't see any bubbled capacitors on the board.



I noticed there was a scorched area around a group or resistors, but those tested fine when off the board so I soldered them back on.



Is there anyone left that is selling this power board?

Re: 3 flashing lights, bad power board?

Posted: Mon Aug 31, 2015 10:45 pm
by ChubbsTech
Hello,



You mentioned you had replaced the color wheel previously. How long ago was this ? The reason I ask is that you also mentioned that this buzzing sound would be noticeable at times when the TV would shut itself down. Color wheels when starting to fail will make more of a humming sound which sometimes can easily be mistaken for a buzzing sound. When the TV shuts down you will hear a failing color wheel as it comes to a stop. Just wanted to mention this in case maybe this was at all a possibility. Please advise.



Regards,

Re: 3 flashing lights, bad power board?

Posted: Tue Sep 01, 2015 4:47 am
by Xtrattitude4u
Hi Chubs,



I have determined the sound is the lamp arcing but not lighting. I watched the lamp with the cover off, and the instant the lamp lights the buzzing stops. I can also see the lamp arcing coinciding with The noise.



So the lamp won't stay lit even though it's a new lamp, and I bought 2 of them.



I have replaced the ballast and the symptom didn't change.



I have a used power board on the way because I don't think a new power board exists for this TV anymore.



I just discovered 2 very interesting clues tonight though:



1. THE TV WILL STAY ON IF NO HDMI CABLE IS PLUGGED IN.



Seriously, I could not get the TV to stay on for even 1 minute tonight. I unplugged the hdmi cable, and it had been on solid for 90 minutes no issues.



Never has the "Check Signal Cable" message been so beautiful, but makes it all the more painful that I can't watch anything on it! It's sitting here mocking me: "Plug in the cable. I dare you."



So I did, and it shut off within 30 seconds, lamp buzzing and all.



My thought immediately is the lack of voltage being used by the digital board to display video is allowing enough voltage to pass to the DMD and ballast.



2: THE TV SHUTS OFF BEFORE THE LAMP



I just observed the screen going blank before the lamp went out, by about 1 second when it shut itself off. So to me that means the lamp itself did not cause the shutdown. It seems if the DMD wasn't getting enough power it could cause this issue.



I really hope this power board fixes my issue, but at the same time I'm disappointed because I think it's the one part that isn't available anymore.

I could only find a used one on ebay , and of course there's no guarantees about that.



My only other option would be to try to replace individual components on the board, but I'd be willing to do that too.

Re: 3 flashing lights, bad power board?

Posted: Wed Sep 02, 2015 2:31 am
by Xtrattitude4u
I want to clarify that the tv will stay on if no video signal is being sent to it.

The HDMI cable can stay in, but the instant I turn on the device feeding the video signal the tv shuts off.



Could a defective digital board cause an issue where the lamp won't light?

Re: 3 flashing lights, bad power board?

Posted: Fri Sep 04, 2015 1:06 am
by ChubbsTech
I bad digital video board can't prevent the lamp from turning on. I must say your situation does seem a little odd. I will do a little research and see if maybe I can track one of these power boards for you. Also I want to look further into your symptoms. I will post a reply for you tomorrow. I am thinking the DMD could be the problem but I want to get a little more information. Please allow me till tomorrow to get back to you regarding your issue.



Regards,