2008 Samsung HL61A750 LED DLP owners thread and FAQ - Page 529 - AVS Forum
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post #15841 of 15855 Old 11-24-2014, 11:12 PM
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2008 Samsung HL61A750 LED DLP owners thread and FAQ

half a turn counter clockwise of the horizontal adjustment knob should do it

Last edited by MagicPotatoes; 11-24-2014 at 11:15 PM.
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post #15842 of 15855 Old 11-25-2014, 06:45 AM
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Originally Posted by MagicPotatoes View Post
2008 Samsung HL61A750 LED DLP owners thread and FAQ

half a turn counter clockwise of the horizontal adjustment knob should do it

I found this image on the link you posted and find that it's a pretty common issue. Have you done the adjustment yourself? Is it as easy as sticking my hand back there and turning the knob? I hope to mess around with it this weekend. Thanks

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post #15843 of 15855 Old 11-25-2014, 08:17 AM
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Originally Posted by eddysnake View Post
I found this image on the link you posted and find that it's a pretty common issue. Have you done the adjustment yourself? Is it as easy as sticking my hand back there and turning the knob? I hope to mess around with it this weekend. Thanks
Yes, very easy. Just have someone watching the TV while you're in there turning it..they'll be able to see the shadow either getting bigger or smaller, and then can tell you when to stop.
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post #15844 of 15855 Old 11-25-2014, 08:24 AM
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Yes, very easy. Just have someone watching the TV while you're in there turning it..they'll be able to see the shadow either getting bigger or smaller, and then can tell you when to stop.
Thanks, is this just a temporary fix to a much bigger issue that I should prepare for down the road? Didn't really see too much on what is causing this to happen out of nowhere.

also, this is the first time I'll be in the guts of the TV, should I get dust off and give anything a good cleaning while the back is off?
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post #15845 of 15855 Old 11-25-2014, 09:03 AM
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Originally Posted by eddysnake View Post
Thanks, is this just a temporary fix to a much bigger issue that I should prepare for down the road? Didn't really see too much on what is causing this to happen out of nowhere.

also, this is the first time I'll be in the guts of the TV, should I get dust off and give anything a good cleaning while the back is off?
No bigger issue...the knobs tend to drift for some reason.

Yes, you should vacuum where you can. If you're a bit more ambitious, slide the "light engine" (where the LED's are mounted) out, remove the cover, and vacuum those heatsinks.

Search for replacing the LED's for instructions on how to do that part. I would highly recommend doing this, you'll be amazed at the dust on those heatsinks.
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post #15846 of 15855 Old 11-25-2014, 09:17 AM
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Originally Posted by bahill View Post
No bigger issue...the knobs tend to drift for some reason.

Yes, you should vacuum where you can. If you're a bit more ambitious, slide the "light engine" (where the LED's are mounted) out, remove the cover, and vacuum those heatsinks.

Search for replacing the LED's for instructions on how to do that part. I would highly recommend doing this, you'll be amazed at the dust on those heatsinks.
thank you, do I need anything else but power to the tv connected to fix the shadow issue?
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post #15847 of 15855 Old 11-25-2014, 09:20 AM
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thank you, do I need anything else but power to the tv connected to fix the shadow issue?
Power and a signal so your 'spotter' can see a picture on the screen with the shadow visible.
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post #15848 of 15855 Old 11-25-2014, 07:42 PM
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Well....i took apart my baby tonight. Getting more brights spots and dark spots. I heard one of the fans starting to whine so I had to do something before something burned up.

I pulled the Engine out. Something rattled. I turned it upside down and a component fell out. Turns out it was one of the inductors in the LED driver module. I could solder it back in, but why did it come off in the first place? No real signs of over heating......
Also checked out the PS....yep....leaking caps. Again....no biggie as I have a nice Pace kit that doesn't get enough use.

So....needing the following:
- replacement caps for the PS board
- replacement DMD
- 3 new fans
- LED driver module

I couldn't find the LED driver module. I'm sure I could find suitable replacements for the fans. Caps are easy. DMD is $350......
I don't want to use pulled parts since I could spend $1500 and it be dead in another month. I, like most here, love this TV, but it has me a bit ticked. I should get more than 5 years out of a TV.

So......is this even possible to repair? $3k can get me a nice 75" with a warranty.
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post #15849 of 15855 Old 11-25-2014, 07:46 PM
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A DMD is only $189 new at many many online places.
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post #15850 of 15855 Old 11-26-2014, 12:40 PM
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I should get more than 5 years out of a TV.
i had a nice conversation with the tech who repaired mine, he does a lot of tv repairs and seemed like he really knew his stuff. I asked him about life expectancy on new tv and he said that he sees most of them getting 7 years at most. i was pretty depressed when he told me that.
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post #15851 of 15855 Old 11-26-2014, 01:47 PM
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Originally Posted by larrylwill View Post
A DMD is only $189 new at many many online places.
i found it at a vendor and ordered it. Got the three fans coming too. The only thing I couldn't get was the LED Driver module. I was going to unclutter my hobby desk anyway.....I just need to get it done this weekend. Then I can set up the Pace kit and put the inductor back on.

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Originally Posted by detroit_fan View Post
i had a nice conversation with the tech who repaired mine, he does a lot of tv repairs and seemed like he really knew his stuff. I asked him about life expectancy on new tv and he said that he sees most of them getting 7 years at most. i was pretty depressed when he told me that.
thats why i couldn't see paying $3000 for something that won't last very long. the way i see it, if i can fix this and it lasts another 4 or 5 years, it'll be time to upgrade, because by then 4k TVs will be old technology.


wish me luck.
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post #15852 of 15855 Old 11-26-2014, 04:47 PM
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Quote:
Originally Posted by tribbler View Post
... Turns out it was one of the inductors in the LED driver module. I could solder it back in, but why did it come off in the first place? No real signs of over heating..
Sounds like your LED driver might be missing the heatsink bar across the row of inductors. I've seen driver modules with it and without it, and sometimes you have to move the bar from the old module to the replacement, if it doesn't have one.
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I don't want to use pulled parts
That may not be an option for the modules, as there are no "new" ones anymore. You can get new LEDs and DMDs, but not modules.

As for LED driver modules, they show up on ebay periodically, and are snapped up almost immediately. You need to enter a search with a 'notify' option, to get an email when a part becomes available. I scored a LED driver earlier this year by that method.

You may luck out by just remounting the loose inductor, if nothing else is wrong. I use the lower LED brightness settings (i.e. not 'auto' or 'dynamic') to minimize the thermal stress on the driver. Those LEDs can draw 25~30 amps peak, and I imagine that heats up the driver a lot. Just my $.02.
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post #15853 of 15855 Old Yesterday, 10:32 AM
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Originally Posted by cosmicvoid View Post
Sounds like your LED driver might be missing the heatsink bar across the row of inductors. I've seen driver modules with it and without it, and sometimes you have to move the bar from the old module to the replacement, if it doesn't have one.
i've attached a pic of the driver board. You can see where the one inductor is supposed to be. You're saying that there should be a heatsink across the top of those? If that is true, I'd like to get my hands on that. as it is, there is only some "heatsink tape" across the top of the heatsink for the mosfets there behind the inductors.


Quote:
Originally Posted by cosmicvoid View Post
You may luck out by just remounting the loose inductor, if nothing else is wrong. I use the lower LED brightness settings (i.e. not 'auto' or 'dynamic') to minimize the thermal stress on the driver. Those LEDs can draw 25~30 amps peak, and I imagine that heats up the driver a lot. Just my $.02.
I weighed that......the TV "seemed" to be working fine without it so I'm betting that just resoldering it will be ok. Hoping is more like it. I don't have my brightness up very high either, which is probably why it lasted as long as it did. 2 cents much appreciated.
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post #15854 of 15855 Old Today, 12:05 AM
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Quote:
Originally Posted by tribbler View Post
i've attached a pic of the driver board. You can see where the one inductor is supposed to be. You're saying that there should be a heatsink across the top of those?
Here is a pic of a driver module with the inductor heatsink. There are actually 2 heatsink sections end-to-end, each about 3" long. There is room for a 3rd section, but I haven't seen a module with 3 sections. Maybe those last 3 inductors don't need it so much.

But, IMO, the inductor heatsink looks like an afterthought. The sinks aren't fastened on other than by the stickyness of the thermal foam, which is like the white stuff under the mosfets. The dark gray thicker foam on the top on the sinks is squeezed by the module lid (you can see the bumps from the lid perforations), which holds the sinks in place.

If you were to add sinks to the inductors (or move them to another module) it would be best to buy some thermal pad material, which can be had from DigiKey for $7 per 9"sq sheet:

http://www.digikey.com/product-detai...115-ND/2445395

or search Amazon for "thermal pads heatsink".
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post #15855 of 15855 Old Today, 02:18 AM
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Screen Size

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Originally Posted by cosmicvoid View Post
The picture size is not electrically adjustable. It depends on the mechanical relation of the DMD to the lens and mirrors. So the only thing to try is adjusting the position of the DMD circuit board. There are 3 screws, protected by plastic caps, that allow that adjustment. Loosten those screws and use your fingers to slide the DMD board assy around. This is a tedious thing to do, as you need a big mirror or a 2nd person to watch the screen. You need to display a grid type of test pattern that has centering lines, and its kind of fussy to get it right, and you may not really gain much change in image size.

My experience on this is limited, so you may wish to experiment a bit.
Too bad about it not having electronic adjustment. What you say makes sense though re: DMD Board positioning via the screws as I believe that while I finally got good H/V positioning I may not have tightened down the 3 screws as much as original. Perhaps that means board is 'further' out from mirrors effecting picture size and being further away would mean larger. Thanks.
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