2008 Samsung HL61A750 LED DLP owners thread and FAQ - Page 523 - AVS Forum
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post #15661 of 15805 Old 05-23-2014, 04:56 PM
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Originally Posted by Piratefan View Post

SUCCESS!!

The guy that I bought the board from replied and gave me a tip. The connector with the wires has a tab on it, like most, and I was pushing it in like you're supposed to. But my fingers were too fat, and it wasn't releasing at the bottom (the whole tab was being pushed in). You push the TOP of the plastic clip/retainer and the bottom of it pops out, releasing the connector to be pulled out. A pair of needle-nose did the trick, once I knew what I was supposed to be looking for. I then took the entire sub-chassis out, so it will be easier to install the new board without reaching inside the TV chassis.

Many thanks for the assistance. Awesome forum!

Have a great day. smile.gif

Well, the power supply board is installed. Guess what? It does the same thing it did prior to installation. It won't stay on long enough to install the updated firmware through the WiseLink USB port. I guess it must be the sub-power supply board????? Incidentally, I had to replace the fan behind the sub-power supply board two years ago, if that matters. Might have damaged the caps by getting to warm????

Anything special I should look for? It looks fine to the naked eye, which means little, I know. But I can't see any cooked caps, like I've seen in some cases.

I believe this is the correct part # for the sub-board: Samsung BP96-01726A. If it's not, please advise. I haven't removed it, yet, so the numbers are a little hard to read. I didn't want to remove and buy that part, if someone had a better suggestion.

Based on what I've read, the DMD DLP chip usually fixes the "white dot" problem. I don't have that problem, but does anyone know if the "cycling on and off" problem has taken the chip to repair that problem? I don't want to just keep buying parts helter skelter, although the cost of the main power supply board wasn't bad, and neither is the sub-board. In every case I've heard, the problem was cured by replacing one of these three parts.

Thanks, in advance.
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post #15662 of 15805 Old 05-25-2014, 12:00 AM
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...
I believe this is the correct part # for the sub-board: Samsung BP96-01726A. If it's not, please advise.

The last letter is wrong; you want a BP96-01726B.
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post #15663 of 15805 Old 05-25-2014, 09:22 AM
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Thanks cosmicvoid,

I have it out, now. Your correction is confirmed. Figures, they are about 50-100% more expensive (that I have found) than the "A" model. Doesn't really matter much, though.

I think I should try to find some lovsl reputable TV repairman to check the sub-board, and the original main board I have replaced, before I just keep buying parts. What do you think?

As I mentioned, the tech from the parts house I bought the main board from thinks it's in the LED(s), but I've found no evidence online that the on & off cycling is caused by them or the DMD DLP chip. (Usually fixes the whtie dot problem).
Your opinions are appreciated.

Thanks, again.
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post #15664 of 15805 Old 05-25-2014, 09:01 PM
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Originally Posted by Piratefan View Post

... I think I should try to find some lovsl ?? reputable TV repairman to check the sub-board, and the original main board I have replaced, before I just keep buying parts. What do you think?
My first thought is that the fee for this repairman would probably pay for a few replacement parts.

My second thought is that I would start by following the troubleshooting guide in the service manual ( which can be downloaded ), assuming you have the skill and some test equipment.

But I was an electronic engineer/programmer (before retiring), so I don't hesitate to dig into appliances that need repair. I don't know how motivated you are.
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post #15665 of 15805 Old 05-25-2014, 10:10 PM
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I've got a spare main input board assembly if anybody is interested. I bought it on eBay a few years ago. It's a take out that was removed from a new TV by a Best Buy tech back in the day. It wasn't faulty and causing the TV's issue so they found out. I tested the board in a problem set that I ended up returning, and all the inputs worked fine without any problems noted while testing. I paid $275 for it.
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post #15666 of 15805 Old 05-25-2014, 10:50 PM
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CLIFF NOTES:  TV acted as if it was powering on/off along with a "hot electronics" (I wouldn't call it "fried electronics") smell. I unplugged for 20 minutes and replugged in. At that point it wasn't cycling, had no picture but it did have sound. I unplugged/plugged it again and this time I dont get anything just a couple on/off cycles, then all three LEDs flash, then it on/off cycles again, LED flash etc. Questions: 1)  I need to either confirm the power supply is the correct fix, or be pointed where to start trouble shooting. 2) Did I experience the on/off cycle issue? 3) Which components are worth money in this thing, and is there a good resource for identification, removal and pricing? 4) Best resource for additional troubleshooting/fixing?

 

LONG VERSION:

Hey guys, my A750 decided to crap out on me today. I've been doing research for the past few hours and am starting to come to the conclusion that I need to replace my power supply but would like to verify this seems like the correct assumption for the symptom im experiencing. Typically I'm more than happy to read through an entire thread, but after getting through about 30 pages (plus numerous other forums/videos), the 500+ pages left discouraged me a bit.

 

When it first happened, the TV started cycling on/off and there seemed to be a "hot electronics" smell - not like something completely fried but rather something got really hot, not sure if that makes sense. I tried the power button and it didn't work, so I just unplugged it, mainly because of the burning smell. At this point I did not know about the LED lights in front giving the error codes, so I am not sure what it was saying if anything.

 

I then plugged it back in about 20 minutes later. It was no longer cycling and I dont believe it had any errors on the LED's (I still haven't found out about that yet, so I cant say for certain) - it didn't have any picture at this point but I was already looking around online and found no picture with sound is a "common" issue. I think I was actually on a tube DLP forum at that point, but regardless I did have sound with no picture.

 

I took apart the back of the TV, feverishly searching for some magical blue switch tube DLPs have (again, not realizing I was comparing apples to orangutangs), unplugging and plugging back in any connectors I could find and half-ass-ingly cleaning the 5 years of dust accumulation. After another 20 minutes of non-sense, plugging and unplugging the TV, yelling at my dog for really no reason at all and loud cursing - I've conceded that I officially have a broken TV with three flashing lights which seem to indicate the lamp is defective, but info I've read on this forum I'm not so convinced its truly a lamp issue.

 

It seems as if there is an on/off cycling issue that can be fixed with firmware. I've never updated my firmware, so it seems that could possibly apply to me?.

 

Few additional questions:

Does it sound like typical power supply issue?

 

What is my best source for additional trouble shooting/repair instructions?

 

Did I experience what you guys on the forum are referring to as the on/off cycle and if so is there any way to update the firmware without having any picture?

 

If I can't fix it, it looks like some of these components are worth money. Is there a good source to look at removal, testing, and pricing for these components?

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post #15667 of 15805 Old 05-25-2014, 11:05 PM
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Quote:
Originally Posted by remerbt View Post

... but after getting through about 30 pages (plus numerous other forums/videos), the 500+ pages left discouraged me a bit.

You should have looked at the last 20 or 30 pages, to see what the late-life problems are. This issue has been discussed recently.
Quote:
... cycling issue that can be fixed with firmware. I've never updated my firmware, so it seems that could possibly apply to me?.

I guess you'd have to wait until you can get a picture to see what version your firmware is. There is an upgrade if you have a version lower than 1005.3.
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post #15668 of 15805 Old 05-26-2014, 01:03 AM
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Quote:
Originally Posted by cosmicvoid View Post

My first thought is that the fee for this repairman would probably pay for a few replacement parts.

My second thought is that I would start by following the troubleshooting guide in the service manual ( which can be downloaded ), assuming you have the skill and some test equipment.

But I was an electronic engineer/programmer (before retiring), so I don't hesitate to dig into appliances that need repair. I don't know how motivated you are.

"LOCAL" reputable TV repairman, I meant. Sorry for typo.

Encompass has the sub-board for $56, new. I can always sell it, or possibly return it. It's an easy remove/install. That would be about as far as I would go on my own. Can't get much labor for $56, but I'm not married to that idea, yet.

I'm pretty much a plug and play guy. I have a multi-meter, but I don't claim to be an expert with it. I'm an old musician (as a hobby), so most of my electronics experience is with tube guitar amps, and related electronics like speaker wiring, etc. I'm not a circuit board guy, but I can follow instructions well. I'm pretty patient and I enjoy learning how to fix, and fixing, most anything.

Where is the best place to download the service manual? I'm not sure I will go beyond the sub-board replacement on my own, though. Still undecided.

Thanks.
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post #15669 of 15805 Old 05-26-2014, 01:04 AM
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Quote:
Originally Posted by remerbt View Post

CLIFF NOTES:  TV acted as if it was powering on/off along with a "hot electronics" (I wouldn't call it "fried electronics") smell. I unplugged for 20 minutes and replugged in. At that point it wasn't cycling, had no picture but it did have sound. I unplugged/plugged it again and this time I dont get anything just a couple on/off cycles, then all three LEDs flash, then it on/off cycles again, LED flash etc. Questions: 1)  I need to either confirm the power supply is the correct fix, or be pointed where to start trouble shooting. 2) Did I experience the on/off cycle issue? 3) Which components are worth money in this thing, and is there a good resource for identification, removal and pricing? 4) Best resource for additional troubleshooting/fixing?

LONG VERSION:
Hey guys, my A750 decided to crap out on me today. I've been doing research for the past few hours and am starting to come to the conclusion that I need to replace my power supply but would like to verify this seems like the correct assumption for the symptom im experiencing. Typically I'm more than happy to read through an entire thread, but after getting through about 30 pages (plus numerous other forums/videos), the 500+ pages left discouraged me a bit.

When it first happened, the TV started cycling on/off and there seemed to be a "hot electronics" smell - not like something completely fried but rather something got really hot, not sure if that makes sense. I tried the power button and it didn't work, so I just unplugged it, mainly because of the burning smell. At this point I did not know about the LED lights in front giving the error codes, so I am not sure what it was saying if anything.

I then plugged it back in about 20 minutes later. It was no longer cycling and I dont believe it had any errors on the LED's (I still haven't found out about that yet, so I cant say for certain) - it didn't have any picture at this point but I was already looking around online and found no picture with sound is a "common" issue. I think I was actually on a tube DLP forum at that point, but regardless I did have sound with no picture.

I took apart the back of the TV, feverishly searching for some magical blue switch tube DLPs have (again, not realizing I was comparing apples to orangutangs), unplugging and plugging back in any connectors I could find and half-ass-ingly cleaning the 5 years of dust accumulation. After another 20 minutes of non-sense, plugging and unplugging the TV, yelling at my dog for really no reason at all and loud cursing - I've conceded that I officially have a broken TV with three flashing lights which seem to indicate the lamp is defective, but info I've read on this forum I'm not so convinced its truly a lamp issue.

It seems as if there is an on/off cycling issue that can be fixed with firmware. I've never updated my firmware, so it seems that could possibly apply to me?.

Few additional questions:
Does it sound like typical power supply issue?

What is my best source for additional trouble shooting/repair instructions?

Did I experience what you guys on the forum are referring to as the on/off cycle and if so is there any way to update the firmware without having any picture?

If I can't fix it, it looks like some of these components are worth money. Is there a good source to look at removal, testing, and pricing for these components?

This is the exact same problem I have/had. That is what cosmicvoid and I are discussing the fix for.
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post #15670 of 15805 Old 05-26-2014, 12:46 PM
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Quote:
Originally Posted by Piratefan View Post

... I have a multi-meter, but I don't claim to be an expert with it.
That is probably adequate, as you'd be doing voltage or resistance checks.
Quote:
... Where is the best place to download the service manual?
I'm not sure. The site that I downloaded from years ago is no longer online, so you will have to go searching. As a last resort, you can buy the pdf file from Samsung for $12.

http://www.samsungparts.com/Products/Parts_and_Accessories/PID-SM-HL61A750A1F.aspx

There are 5 modules that do most of the work:
Main PS - power to everything except LED driver
Sub-PS - power to LED driver
Main board - Tuner, inputs, video & audio proc
LED driver - drives LEDs (duh)
DMD board - DMD chip and driver

and a few small boards that rarely fail.

There may be a heat-related problem, so check that the fans are working, and the heatsinks are not clogged with dust.
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post #15671 of 15805 Old 05-26-2014, 01:19 PM
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Finally replaced my DMD chip after it set on table for a couple of months.
Pretty easy, didn't need any adjustments after install (took about 30 minutes).
Only precaution is to be sure and replace heat sink pad with heat sink
compound. Mine was completely dried out which may have caused chip
failure due to excess heat.
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post #15672 of 15805 Old 05-26-2014, 01:31 PM
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Quote:
Originally Posted by cosmicvoid View Post

That is probably adequate, as you'd be doing voltage or resistance checks.
I'm not sure. The site that I downloaded from years ago is no longer online, so you will have to go searching. As a last resort, you can buy the pdf file from Samsung for $12.

http://www.samsungparts.com/Products/Parts_and_Accessories/PID-SM-HL61A750A1F.aspx

There are 5 modules that do most of the work:
Main PS - power to everything except LED driver
Sub-PS - power to LED driver
Main board - Tuner, inputs, video & audio proc
LED driver - drives LEDs (duh)
DMD board - DMD chip and driver

and a few small boards that rarely fail.

There may be a heat-related problem, so check that the fans are working, and the heatsinks are not clogged with dust.

I don't know if I mentioned this above, but the fan behind the sub-PS died two years ago. I replaced it, and had no problems until the on and off cycling began a couple weeks ago. In considering the replacement of the sub-PS, the fact that the fan behind it died at some point has made it more of a suspect. All of the fans are working properly, now, and I have cleaned them all, plus every other surface I could reach.

I'm leaning toward buying the sub-PS board for $60 incl shipping. That's a brand new board. I have the old sub-board out now, so that would be a super-easy installation. With the prior fan issue, and the fact that it controls the power to the LED's, makes me lean towards that being the culprit. If I get it and that doesn't fix it, then either I'm out $60, I can sell or return it, or I have a spare for the future, since they do fail fairly frequently.

If it does not fix it, then I think it's over my head, and I need to take it to a Pro, at least for diagnosis. Mainly because of the cost of the DMD board and LED driver. (not like spending $50-60 and taking a small chance). I know I can install the DMD board, but I wouldn't invest that much money without first diagnosing it was the problem, for sure....... I may download the service manual anyway, and if it looks like something I can do with my multi-meter, then I can attempt to diagnose it myself. Either way, the sub-PS board would be as far as I would go without careful diagnosis either by me w/ service manual, or by a professional repairman.

Does that sound like a "sound" plan?
Thanks.
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post #15673 of 15805 Old 05-26-2014, 04:50 PM
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Quote:
Originally Posted by Piratefan View Post


 I have a multi-meter, but I don't claim to be an expert with it.

Where is the best place to download the service manual? I'm not sure I will go beyond the sub-board replacement on my own, though. Still undecided.

Thanks.

 

Here is the manual - I found it in a post a few pages back: http://www.epanorama.net/sff/Video/Products/SAMSUNG%20HL67A750.pdf

 

There is a flow chart in there to diagnose, it recommends checking power coming from the sub board, it is the 6 wire (1 black, 5 gray) plug right in front. Its by fair the easiest thing to get a reading on with the multimeter. You should get 16v on pins 2/4/6 (the very top black wire is #1 and is ground, as are 3 and 5)... I dont know that that would tell you exactly if its bad or not, perhaps someone else could chime in as to what that may mean.

 

Quote:
Originally Posted by cosmicvoid View Post


You should have looked at the last 20 or 30 pages, to see what the late-life problems are. This issue has been discussed recently.
I guess you'd have to wait until you can get a picture to see what version your firmware is. There is an upgrade if you have a version lower than 1005.3.

 

My apologies, I did look through the last 10 pages or so, somehow skipping yours and Piratefan's discussion.

 

Todays progress (sort of):

So I went through the service manual and did all the tests that it asked. I think I am more confused than I was when I started. My results:

 

"Check Logic Power" - had 12v on CN9007 pin 18, 5v  on 21/22 on both sides, at DMD and at the end of the cable that goes into the driver

 

"Check Driver Power" - had 16v at 2/4/6

 

It didn't ask for it, but the LED's had 16v each

 

I tried the R9010 ground as suggested, but wasn't exactly sure if I was doing it right or not. I basically used a small wire to "jump" the two connections outlined in the manual. They were extremely tiny targets, with shaky hands while also trying to look at the LED. However, I did eventually get a green dot.

 

The confusion parts:

 

#1 - The TV was doing the same thing this morning as it was last night - powering on, turning off, coming back on with all 3 lights blinking, power off, come back on with just green like blinking - repeat over and over

 

2# - First thing I did was take out all components (all 3 assemblys), blow them off with condensed air and put it back together. I fired it back on and it was no longer cycling - it was just "on" with no picture (I moved the TV to my office to work on it, so it wasnt connected to any video source - so I dont know if the volume was working or not).

 

#3 During my testing, I noticed that the tv would do the cycling any time any of the cables were disconnected. When I had them all connected it would not cycle. HOWEVER - it is now cycling again and all cables are connected.

 

#1 - What should I consider a succesful LED light up? An 1/8" dot, or full on glowing?

 

#2 - When I got the green dot on the grounding test, it stayed on for a while. I even unplugged it, then plugged it back in and it came on. I put the assembly back together and the green dot went away. Cycled it a couple times and it came back on, but would "cut out" like it was a bad connection. While the green light was on I tried to push the assembly back in the housing to see if the screen would have picture, but alas it did not. I dont know if its because the green light went off, or because that 1/8" dot isn't truly the LED lighting up.

 

#3 - All 3 LEDs gave that same 1/8" dot with a 9 volt battery.

 

4# There didn't seem to be any mention in the manual how to test the main SMPS or the main board. Perhaps I missed it and perhaps its discernable from the schematics. I'm not an electronics guy, and while I can figure out schematics it would take me quite some time to try to decipher through all of them to find "the answer"

 

#5 - 4 hours of researching and trouble shooting, and I still have no idea what the hell is going on, but for some reason I have a particular eye on the main board and the LVDS cable from the main board to the DMD board (it just feels like a weak connection).

 

Specific questions:

 

#1 - How do I check the LVDS cable - just continuity?

 

#2 How do I check the main board?

 

#3 How do I check the main SMPS?

 

 

Thanks for any advice in advance as well as any other suggestions/comments etc are appreciated.

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post #15674 of 15805 Old 05-26-2014, 06:09 PM
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Thanks for the manual, Remerbt.
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post #15675 of 15805 Old 05-27-2014, 03:15 PM
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I ordered the BP96-01726B today from Best Buy Parts store. Brand new, and they will take it back for full return if it isn't the cure for my problem. Other than time and trouble, no cost to me if it's not the source of the problem. $54.19 w/free shipping, fyi.

Somehow, I don't think its the DMD chip, since the picture was perfect before the turning on/off began.

So, in summary, main power supply board has been replaced, sub-power supply board is on its way, and updated firmware is on a memory stick, ready to install. Fingers crossed.
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post #15676 of 15805 Old 06-07-2014, 12:31 PM
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Quote:
Originally Posted by cosmicvoid View Post

That is probably adequate, as you'd be doing voltage or resistance checks.
I'm not sure. The site that I downloaded from years ago is no longer online, so you will have to go searching. As a last resort, you can buy the pdf file from Samsung for $12.

http://www.samsungparts.com/Products/Parts_and_Accessories/PID-SM-HL61A750A1F.aspx

There are 5 modules that do most of the work:
Main PS - power to everything except LED driver
Sub-PS - power to LED driver
Main board - Tuner, inputs, video & audio proc
LED driver - drives LEDs (duh)
DMD board - DMD chip and driver

and a few small boards that rarely fail.

There may be a heat-related problem, so check that the fans are working, and the heatsinks are not clogged with dust.

Well, I installed the sub-power supply board (already installed main power supply board), and I still have the exact same problem. No picture, one green light blinks for a while, then the Samsung jingle plays, and all three LED's start blinking, then it goes off again, with only one light blinking. Rinse, repeat... Won't turn off until I unplug it. Cleaned it all well, while I was in there, especially the fans.

To me that leaves only the DMD chip, and the LED's. Too expensive to keep doing the trial and error thing, so I think it's time to call somebody that is more experienced with the proper tools for diagnosis. I'm just not that comfortable with that duty. I don't mind keeping the power supplies that I have bought. Only have about a $100 in them, and since they seem to fail and are somewhat scarce, it would be worth it to me to have them here. I just wish I had a TV tech around here that I trusted. Most are either real old-school, and don't like to work with newer LED TV's, or are just plug and play guys.

Thanks for all the help, regardless.
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post #15677 of 15805 Old 06-07-2014, 05:07 PM
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Quote:
Originally Posted by Piratefan View Post

Well, I installed the sub-power supply board (already installed main power supply board), and I still have the exact same problem. No picture, one green light blinks for a while, then the Samsung jingle plays, and all three LED's start blinking, then it goes off again, with only one light blinking. ... To me that leaves only the DMD chip, and the LED's.

Yeah, it looks like you've narrowed it down to the LED driver board. I don't suspect the DMD chip/board, but thats my gut feeling. I don't remember whether you tested the individual LEDs with a 9v battery, and I'm too lazy to read your previous posts. With the light tunnel open, do you see any LED light during startups?
Quote:
Too expensive to keep doing the trial and error thing

Perhaps, but the LED driver modules pop up on ebay every few weeks; I bought one for my board stash a few months ago, cost me $68. You have to set up email notification on ebay for that item, as they tend to sell out almost immediately.
Quote:
I think it's time to call somebody that is more experienced with the proper tools ... snip... Most are either real old-school, ... or are just plug and play guys.

With the modular construction of electronics now, there isn't much you can do except plug and play. Actually fixing a bad module is not for the faint of heart, as beside needing the test equipment and a set to host the module, you need to understand how its supposed to work and what the signals should look like. And then good luck if you need to replace one of the custom LSI chips (i.e. where to find them except from another module).

So I can give you free advice and encouragement to persevere, but ultimately it's your money.
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post #15678 of 15805 Old 06-07-2014, 05:38 PM
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Quote:
Originally Posted by cosmicvoid View Post

Yeah, it looks like you've narrowed it down to the LED driver board. I don't suspect the DMD chip/board, but thats my gut feeling. I don't remember whether you tested the individual LEDs with a 9v battery, and I'm too lazy to read your previous posts. With the light tunnel open, do you see any LED light during startups?
Perhaps, but the LED driver modules pop up on ebay every few weeks; I bought one for my board stash a few months ago, cost me $68. You have to set up email notification on ebay for that item, as they tend to sell out almost immediately.
With the modular construction of electronics now, there isn't much you can do except plug and play. Actually fixing a bad module is not for the faint of heart, as beside needing the test equipment and a set to host the module, you need to understand how its supposed to work and what the signals should look like. And then good luck if you need to replace one of the custom LSI chips (i.e. where to find them except from another module).

So I can give you free advice and encouragement to persevere, but ultimately it's your money.

I haven't even gone that far, cosmicvoid. All I have done is replaced those two power supply boards, so I haven't discovered the light tunnel, and obviously haven't checked to see if there was any LED on during startup. All I have really done is read a lot, looked at a lot of videos and replaced those two power supply boards. It's been down long enough now that I don't mind taking the time to be extra careful I don't screw something up. I've used a multi-meter so little, I don't trust myself to do what needs to be done with it. And I haven't checked anything for voltage.

When I said that about the money, I was thinking a long the lines of a DMD chip costing nearly $200, and that money might be better spent getting an experienced person to diagnose that actual problem. If it's the LED driver board, how would I diagnose that? So you won't have to look back, the picture was absolutely perfect before it started shutting down. No white spots. No green screen. Perfect. If it wasn't I would just go buy a new TV. My only thing about the money is that I spend it where I should.. wisely. Not trying to be el cheapo, though.

If you would be kind enough to offer some diagnostic steps, I will give it a go.
Thanks,
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Quote:
Originally Posted by Piratefan View Post

... If it's the LED driver board, how would I diagnose that?

You've pretty much done that already.
Quote:
... the picture was absolutely perfect before it started shutting down. No white spots. No green screen...

So there's no reason to suspect the DMD area.

The LED driver module is on the right side (looking from the rear), and has 3 two-wire cables on the top (blue/white, green/white, red/white). You have to remove the optical section ("the engine") from the chassis to get to this module. That is shown in section 3-1-8 of the service manual. There is probably a video that shows how to do this, but I haven't looked. There are cables that must be disconnected from the optical section (from Sub-SMPS and main board) before sliding it out.

I guess if you are not confident about doing this, then maybe a repairman would be an easier path. But you would still need the LED driver module, regardless of who replaces it, and I doubt a repairman could get it any cheaper than you could (I don't know about faster). I'm thinking that perhaps you should assume the individual LEDs are OK, and not try testing them with a battery, because if you connect backwards, you could fry the LED.

Have you seen any video about this repair? Are you willing to dig into this yourself? Have you tried to get an estimate from a repair shop?
http://www.avsforum.com/t/1493442/samsung-hl61a750-led-driver-fault-heatsink-on-replacement

I don't want take time to go into details unless you want to do this yourself.
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post #15680 of 15805 Old 06-08-2014, 06:47 AM
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Quote:
Originally Posted by cosmicvoid View Post

You've pretty much done that already.
So there's no reason to suspect the DMD area.

The LED driver module is on the right side (looking from the rear), and has 3 two-wire cables on the top (blue/white, green/white, red/white). You have to remove the optical section ("the engine") from the chassis to get to this module. That is shown in section 3-1-8 of the service manual. There is probably a video that shows how to do this, but I haven't looked. There are cables that must be disconnected from the optical section (from Sub-SMPS and main board) before sliding it out.

I guess if you are not confident about doing this, then maybe a repairman would be an easier path. But you would still need the LED driver module, regardless of who replaces it, and I doubt a repairman could get it any cheaper than you could (I don't know about faster). I'm thinking that perhaps you should assume the individual LEDs are OK, and not try testing them with a battery, because if you connect backwards, you could fry the LED.

Have you seen any video about this repair? Are you willing to dig into this yourself? Have you tried to get an estimate from a repair shop?
http://www.avsforum.com/t/1493442/samsung-hl61a750-led-driver-fault-heatsink-on-replacement

I don't want take time to go into details unless you want to do this yourself.

I will read the service manual section you listed above, and check for videos..... In the morning, I will call and get a couple of service estimates, also. Then, I'll know better how to proceed.
Really appreciate all your time and trouble.
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post #15681 of 15805 Old 06-08-2014, 10:52 PM
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FYI, a few months ago, I picked up a used HL67A750 (same set that I have) that had "no picture", and I figured I'd see if I could fix it. The previous owner had replaced the sub-SMPS (which had a bulging cap), which didn't fix it. So I thought the first thing to try was replacing the LED driver module. Surprisingly, that didn't fix it. I checked the LEDs, and they each work. With the optical chassis part way out, but still connected, a power-up cycle shows a brief spot of white light from the lens (as expected), which then goes away and after about 15 seconds nothing has happened, so the cycle repeats.

I'm guessing this is similar to what your set is doing. Anyway, since the simple module swap didn't fix it, now I need to go digging deeper to see what is wrong.

I'm just telling you this so you know that some sets are "easy fixes", and some are not. But I guess nothing ventured, nothing gained.
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Hi all... I quoted one of my older posts below. I did edit the quote slightly to be more on topic...

Basically, I've (just now) removed the entire light engine board (leds, lens, fans etc) and am looking to do two things.

One is to replace some bad thermal paste, but the main topic is my light distortions. Based on a PM I from "jeffbon" (the one who posted the below pic) he stated that a tech cleaned and polished his lenses and that corrected the issue... based on that, I'm going to attempt the same.

Any speedy tips on this will be very helpful... even if you don't know exactly what I'm doing... providing tips on removing parts or where to look to replace any thermal paste will be helpful and save me tons of time searching this HUGE thread on the few bits of info I need.

I'm sitting here... looking at the light engine and eagerly awaiting any replies.

Thanks.

Quote:
Originally Posted by Teknomedic View Post


I have a slight "light distortion" problem... Here's a pic from another post....





My issues isn't nearly as bad, but I do have several light "circles" identical to the above pic

Any tips on correcting this issue? I've already ensured that the mirrors and lens are clean and are not the issue so the problem lies on the inside of the lens or deeper... and since this started just after blowing out some dust I suspect it's a dust issue or I blew something lose.

Thanks for any help or tips

TK
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post #15683 of 15805 Old 06-16-2014, 04:42 PM
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tore the DMD board apart and cleaned the chip and mirror as best as I could, seemed like a lot of crap was on the chip after I removed so crossing fingers that was causing my light issue. Also been cleaning the lenses as much as I can. I replaced the thermal tape for the DMD chip with some high quality CPU thermal paste I used for my Intel 4770k CPU so should help keep the chip a little cooler... very disappointed in the quality of the heat-sinks though.

Does anyone know if I can separate the lenses?? I ask because I can clean the back and the front of the lenses, but can see dust between the layers. Lame.

Also, does anyone know if anyone makes a pure copper or better heat-sink for the DMD chip?

Thanks!

Will update if this cleaning job helped my problem or not soon.

TK
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post #15684 of 15805 Old 06-16-2014, 05:20 PM
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SUCCESS!!!

So if you see that type of "light circles" as pictured above, it's basically dust... most likely on the DMD chip. You'll need to pull the light engine board out and start cleaning.

Here are some details:

NOTE: Be aware of ESD and take ESD precautions. You're dealing with electronics and you can fry a CPU or board without even feeling a shock... be sure you're grounded.

Tools needed: Service Manual or other directions on removing the light engine, philips screw driver, needle nose pliers may be needed to assist with removal of wire harnesses, compressed air cans/small air compressor to give you clean and fast air to blow dust off, Q-tips or other cotten cleaning to help remove dust build up the compressed air can't remove. Also consider some high quality CPU thermal paste if you'd like to replace the crappy thermal tape. Probably an hour or two of free time so you don't feel rushed. You also may want to consider buying some nitrile type gloves (the ones paramedics/nurses use) to help keep hand dirt and oil off the mirrors or lenses.

What I did: Pulled the light engine assembly, then removed the "Actuator (smooth picture)" board. This allowed me to clean the front and rear of the lenses and housing. As well as clean the mirror surface of the "Actuator". I then removed the DMD board and DMD chip. I then cleaned the DMD (be super careful here) as well as the mirror and whatever else I could safely reach inside the light tunnel area that the mirror on the DMD chip faces. After this I then decided to replace the thermal tape on the heat sink with some high quality CPU thermal paste.

Once I thought I cleaned as much as I could I put everything back together and found all my little light circles were gone! Woot Woot.

TK
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post #15685 of 15805 Old 06-16-2014, 11:32 PM
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Your tip about using nitrile gloves is an excellent idea.

Canned air is best; mechanically compressed air can have water and oil vapor in it. Bad for optics.

Last edited by cosmicvoid; 06-16-2014 at 11:37 PM.
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yeah...I'm a paramedic by trade, so I always have a few boxes of those gloves around. they come in handy for tons of things, lol.


good tip on the mechanically compressed air too.... didn't know. luckily my little compressor didn't give me any problems like that for this project.

TK
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post #15687 of 15805 Old 06-17-2014, 10:04 PM
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I have another question regarding my 67A750. Purchased the set used, it has always bothered me that with this set that in the service menu Cinema CCA is turned off. If I turn it on, the PQ is whacked (very dark, saturated yellow/orange). This isn't normal for the 750's?

The whacked look with CCA turned on reminds of a 650 once I (somewhat) accidentally activated HDMI calibration. I did get that set straightened out (and in the end it looked notably better) with the help various test patterns via HCFR and a fair amount of fine tweaking with various source material. I'm suspicious the previous owner poked around in there and did the same thing (calibrate HDMI). I can't find an "ADC Result" area on the 750 to investigate this theory. (on the 650, this is where you manually correct/tweak the HDMI calibration: its simply a color temp/gain adjustment, 3 primaries @ black and 100%)
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post #15688 of 15805 Old 06-17-2014, 10:44 PM
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Have you looked at the Lee Bailey service menu threads?

2008 Samsung HL61A750 LED DLP owners thread and FAQ
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post #15689 of 15805 Old 06-19-2014, 10:27 PM
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Quote:
Originally Posted by cosmicvoid View Post
FYI, a few months ago, I picked up a used HL67A750 (same set that I have) that had "no picture", and I figured I'd see if I could fix it. The previous owner had replaced the sub-SMPS (which had a bulging cap), which didn't fix it. So I thought the first thing to try was replacing the LED driver module. Surprisingly, that didn't fix it. I checked the LEDs, and they each work. With the optical chassis part way out, but still connected, a power-up cycle shows a brief spot of white light from the lens (as expected), which then goes away and after about 15 seconds nothing has happened, so the cycle repeats.

I'm guessing this is similar to what your set is doing. Anyway, since the simple module swap didn't fix it, now I need to go digging deeper to see what is wrong.

I'm just telling you this so you know that some sets are "easy fixes", and some are not. But I guess nothing ventured, nothing gained.
Hello again. Had a hellacious week that precluded me from working on the TV at all. I did call a couple of recommended local TV repair shops, and both demanded I take the TV to them, and pay a "bench fee". Pretty normal, but I thought I would take you up on your offer to help me diagnose my TV's problem. I need to take it one step at a time, because this is uncharted territory for me.

Where should I begin, given that both power supplies have been replaced, and the fans are all operational, quiet, and clean? Be gentle. lol
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post #15690 of 15805 Old 06-20-2014, 03:33 PM
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I decided that for my set, the next easiest thing to try is the 'color sensor' board, so I ordered one on ebay last week (for $18), and received it a couple days ago. I'll try replacing that in the next few days. If that doesn't help, then the next thing to try is the DMD board, since that controls the signal to the LED driver. I won't be replacing the DMD chip, just the logic board, but that is a big hassle because once you move the DMD board, I will probably have to adjust the image centering and focus. Thats why I'm trying the color sensor first. Since I know the LEDs are producing light, my theory is that the color sensor is failing to tell the software that light is being detected. But the sensor signal routes through the DMD board, so either could be bad.

As for your set, you could remove the two screws that hold the light engine (optical chassis), and slide the optical chassis out an inch or so, so that the lens is visible. Be careful not to catch the plastic shroud on the brown & blue wires at the top of the compartment. Do not disconnect the cables to the light engine, as you will need to have it operational while you try a power on cycle. Watch the center of the lens to see if you get a spot of light. If no light, then the sub-smps supply or the LED driver or the color sensor or the DMD board could be bad, since they are somewhat inter-dependant. The results of this test will determine what to check next.
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