Samsung LE26R88BD Strange Fault (Main Board??)

[jpalmeida]

Re: Samsung LE26R88BD Strange Fault (Main Board??)

selldoor, thanks for suggestion!
I'll do that.
Best regards.
Joao Almeida

[selldoor]

Re: Samsung LE26R88BD Strange Fault (Main Board??)

Signup has not posted since July -as I said even though your board has the same part number it may not have those ICs - We need a good clear picture of your main board

EDIT
Cross post - ok - I will look out for it.

[Dang]

Re: Samsung LE26R88BD Strange Fault (Main Board??)

Just to clarify here, there's two distinct versions of this board, the one for the M87 has two big ICs just below the "CAM slot" that the R87/88 don't have, I'm quite certain these are there to process the 1080p signal.

[jpalmeida]

Re: Samsung LE26R88BD Strange Fault (Main Board??)

Sorry guys! I didn't see it properly. And yes this board also has the IC1107 & IC1106 but at the other side of the board. They have the same ref but a bit different termination.
So, signup wrote that his ICs are 1117 07152L and mine are 1117 07135L.
Now the problem is to find them to buy :-)
Let's see what I can find!
Joao Almeida

[selldoor]

Re: Samsung LE26R88BD Strange Fault (Main Board??)

What about testing them? these sound like 1117 voltage regulators - pictures?

[suriips450]

Re: Samsung LE26R88BD Strange Fault FIXED

Decided to stop being a wuss when it comes to main boards and did a little more investigation, checked the voltages on the VR's on the underside of the board and found 2 giving funny readings when the fault was happening, against when the TV was working

Board PN= BN41-00813B-MP

IC positions IC1107 & IC1106

Both Voltage regulators were labelled 1117 07152L

Replaced and the TV has been playing for 5 hours now and not a hiccup

Hi Tom,

Hope you are well, do you reckon above regulator is an adjustable or 3.3 or 5V one? I much appreciate your help.

Thanks

[tom66]

Re: Samsung LE26R88BD Strange Fault (Main Board??)

Given the lack of a suffix I'd say adjustable.

[suriips450]

Re: Samsung LE26R88BD Strange Fault (Main Board??)

Many thanks for that Tom66. Plz could u confirm I will be alright with AP1117DG-13, with min input vol 6.4v?

Thanks

[tom66]

Re: Samsung LE26R88BD Strange Fault (Main Board??)

I'd check the input voltage currently and see if it's higher than that, but if that is FARNELL figure, I would take it with a pinch of salt and check the datasheet yourself directly.

[suriips450]

Re: Samsung LE26R88BD Strange Fault (Main Board??)

Many thanks tom66. Just checked with supplier that part is marked as 1117 which is same as the faulty one that I have. Going to place an order. Hopefully I will be alright!

I am concerned about min input vol on this part I am buying is 6.4V and max input vol 18V, as the main boardruns with +13v off PSU I am hoping that I will be alright. Just being bit lazy removing back cover and checking with voltmeter on the input pin of that IC, that's all!

[tom66]

Re: Samsung LE26R88BD Strange Fault (Main Board??)

These main boards also use +5.3V so I would be careful with checking that, though, I have not heard of a 1117 with that low of an input, why not use TLV1117? I use that for all my repairs, a lot more reliable than generic, it is made by Texas Instruments.
http://www.ebay.co.uk/itm/TEXAS-INST...item3f2375d092

[suriips450]

Re: Samsung LE26R88BD Strange Fault (Main Board??)

Thanks for that tom66. I will order.

[Rickig]

Re: Samsung LE26R88BD Strange Fault (Main Board??)

I have this same issue. On looking at the board by those regulators I have a few small burnt out components. Don't suppose anyone knows what they are and what value so that I may replace them
C1123
C1184
And the one below c11?? Can't see as burnt
Board bn41-00813

[glerant]

Re: Samsung LE26R88BD Strange Fault (Main Board??)

Errrmmm so sorry, I need to pay more attention, and look more closely at the boards when checking, I have just spotted a nice rust patches and what looks like water/fluid damage on the main. All under the metal sheilding that looks like a pain in the arse to get off...A new main it is I am not chasing tails to resolve this one

Thanks again Tom

Yep. I had a Samsung LE26R87 with the exact same fault. TV resets every 30 seconds or so - not so much when cold. Video on all inputs good (while the thing is on!) - blanks out and restarts (restart process takes about 20 seconds).

I changed all the NXB electrolytics on the PSU - was just about to pat myself with a job well done and the problem returned. PSU itself behaving itself perfectly on all voltages.

So, I turned my attention to the Mainboard. Here, I saw the exact same thing you described - a brown residue around and on the CPU/GPU shielding. It looked like someone had poured a cup of coffee in the back!

I cleaned it up - fault persisted. Don't have any 1117 5V SOT-252 regs in hand so I took a look at the shielding. Luckily I have a ZD-915 desoldering station so it was fairly easy to take off the board.

Turns out the residue comes from a couple of crappy rubber heatsink blocks stuck to the underside of the shielding that are meant to cool a couple of PGAs. I guess it is left over from some kind of heat transfer grease. The surfaces of the rubber blocks themselves were not in great shape either.

What I did was get a couple of copper shims from ebay - 15mm and 25mm square - 1.2mm thick.
I then put a small layer of heat transfer compound on the chips - and placed and pressed hard down the shims. Then put a little hot snot on the bottom side to stop them slipping being careful not to get any on the upper shim surface. Then put a layer of heat transfer on the underside of the rubber blocks. The hot snot probably an overkill - the extra pressure from the additional 1.2mm shim probably enough to keep the shims in place - but may as well take no chances! :-)
No the tricky bit! Put the small underside shielding/support in place - then the top shielding - somehow kept the pressure on the solder tabs whilst soldering - I know I really needed 4 hands for this but I don't have any helpers! Anyway - all solder tabs soldered whilst putting pressure on the shielding.
Reassembled - the TV has sat all day playing HD video and hasn't reset once - the shielding/heatsink is noticably warmer and so appears to be efficiently removing heat from the chips. I think the design means that once this original heat transfer stuff dissapates the blocks become more insulator than heatsink.

Hope this helps someone with a similar issue - I guess this heat death will happen to all these main boards at some point.

[dick_barton]

Re: Samsung LE26R88BD Strange Fault (Main Board??)

A nice bit of advice for someone with a similar fault.

[vinceroger69]

Re: Samsung LE26R88BD Strange Fault (Main Board??)

Yep. I had a Samsung LE26R87 with the exact same fault. TV resets every 30 seconds or so - not so much when cold. Video on all inputs good (while the thing is on!) - blanks out and restarts (restart process takes about 20 seconds).

I changed all the NXB electrolytics on the PSU - was just about to pat myself with a job well done and the problem returned. PSU itself behaving itself perfectly on all voltages.

So, I turned my attention to the Mainboard. Here, I saw the exact same thing you described - a brown residue around and on the CPU/GPU shielding. It looked like someone had poured a cup of coffee in the back!

I cleaned it up - fault persisted. Don't have any 1117 5V SOT-252 regs in hand so I took a look at the shielding. Luckily I have a ZD-915 desoldering station so it was fairly easy to take off the board.

Turns out the residue comes from a couple of crappy rubber heatsink blocks stuck to the underside of the shielding that are meant to cool a couple of PGAs. I guess it is left over from some kind of heat transfer grease. The surfaces of the rubber blocks themselves were not in great shape either.

What I did was get a couple of copper shims from ebay - 15mm and 25mm square - 1.2mm thick.
I then put a small layer of heat transfer compound on the chips - and placed and pressed hard down the shims. Then put a little hot snot on the bottom side to stop them slipping being careful not to get any on the upper shim surface. Then put a layer of heat transfer on the underside of the rubber blocks. The hot snot probably an overkill - the extra pressure from the additional 1.2mm shim probably enough to keep the shims in place - but may as well take no chances! :-)
No the tricky bit! Put the small underside shielding/support in place - then the top shielding - somehow kept the pressure on the solder tabs whilst soldering - I know I really needed 4 hands for this but I don't have any helpers! Anyway - all solder tabs soldered whilst putting pressure on the shielding.
Reassembled - the TV has sat all day playing HD video and hasn't reset once - the shielding/heatsink is noticably warmer and so appears to be efficiently removing heat from the chips. I think the design means that once this original heat transfer stuff dissapates the blocks become more insulator than heatsink.

Hope this helps someone with a similar issue - I guess this heat death will happen to all these main boards at some point.

Thanks for posting the fix im sure it will help a lot of us out in the future.

[rgreair]

Re: Samsung LE26R88BD Strange Fault (Main Board??)

I Have A very similar problem but in reverse. when cold will not turn on leave it for 15 min it will turn on. i've checked the 1117 on my reader, one comes up as uf = 1.34v c= 84. 8uf and says diode. 0ther one says diode as well uf = 1.34v c= 0nf. and warm in hand c80.6uf and longer c84.8uf. this 1117 is from ic1106. ->l- flow. ic1107 stays steady at any temperature. order theses NCP1117 regulated not fixed. 1A 2.5v min 12v max. handels upto 20v. in. see if these repair the board.

[steviewonder]

Re: Samsung LE26R88BD Strange Fault (Main Board??)

Replace the two 1000uf 10v caps under the heatshield,just right of centre.That should sort yours out rgreir!

[rgreair]

Re: Samsung LE26R88BD Strange Fault (Main Board??)

Thanks steviewonder. replaced them capacitors. C1110 had 4.1% loss C1177 had 1.4% replaced them both with 1000 AFP 6J5 105C. had to order a new solder station as this one has packed in so using gas iron, will finish off when new iron station arrives. thanks

[licbal]

Re: Samsung LE26R88BD Strange Fault (Main Board??)

Estes 1117 são de voltagem fixa ou regulavel , é que não encontro a referencia igual ao que aparece nas Boards , Obrigado