Samsung UN39FH5000FXZA LCD TV power on cycling

[Surrey]

Just out of warranty at one year old, this started out intermittently then got progressively worse, now it takes many cycles for it to work if at all before giving up ;-)

Turn the TV on and it makes the Samsung powerup noise, backlighting comes on but nothing on the screen. After about 15 seconds, it will cycle through the powerup again and keep cycling until it eventually comes on. When it is cycling you can't turn it off to stop this, it has to be unplugged. Plugging it back in results in the same cycling until it finally comes on or until you unplug it. Once on, the TV will work fine for hours till turned off.

No swelled caps or cold solder joints on the PS board, unplug the main board and the backlighting comes on and all voltages seem to be normal and stable at 5.25V and 13.05V, have not load tested them yet. Cursory inspection of the main board under magnification shows no obvious flaws or solder problems.

When the TV finally comes on and you shut it down, the 5V standby voltage is present and stable. Tried unplugging the power button as well as the TCON cable with no change.

The two PS test points indicated in pic read 13V during cycling, the one marked 13V (EY80) goes to 0V when cycling, then back up, but the one marked 15V (EY76) cycles up to 15V and back. With main board unplugged EY80 stays at 13V and EY76 measures 15.4V.

PS BNN44-00666A
Main BN94-07695D

I have basic electronics skills, Fluke meter, good soldering skills, temp controlled iron but no hot air station.

Any help is greatly appreciated.

[budm]

Re: Samsung UN39FH5000FXZA LCD TV power on cycling

Connector CNM803 pin 14 POWER ON-OFF swinging LO and HI (<1 to >2V)?
Pictures provided by SHOPJIMMY.

[Surrey]

Re: Samsung UN39FH5000FXZA LCD TV power on cycling

Yes, 3.5V while backlighting is on for 15seconds then drops briefly to 0V, then next cycle, repeat.

Sorry I didn't upload pictures of the board both sides, and thanks for the help.

[budm]

Re: Samsung UN39FH5000FXZA LCD TV power on cycling

Since the STBY Voltage for the main board is steady by the PS-ON is not, then you have the problem on the main board somewhere.

[Surrey]

Re: Samsung UN39FH5000FXZA LCD TV power on cycling

OK, have I eliminated a TCON problem by disconnecting it with no change?

Also, do you think it may be repairable? I'll have another close look at it under magnification.

Thanks.

Included pics of the back of the TV and both sides of the main board for future.

[CapLeaker]

Re: Samsung UN39FH5000FXZA LCD TV power on cycling

intermittent PSon = main board problem. I think your mainboard is a BN94-06778C. In order to trace, you would have to remove the sticker. Better look for a replacement board.

[Surrey]

Re: Samsung UN39FH5000FXZA LCD TV power on cycling

You are correct on the part number, screwed that up in original post.

PS BN44-00666A
MAIN BN94-06778C

Thanks, will update the thread when repaired.

[Surrey]

Re: Samsung UN39FH5000FXZA LCD TV power on cycling

Update: A close look at the main board under magnification revealed a few questionable solder joints on the regulators, one IC, and the pins of the PS connector. Reflowed them and no change, so I guess without any info on the main board I will just replace it.

I also did voltage checks at the main board connector and all voltages that should be there are present and stable, ruling out a bad cable.

Will update when the board gets here and I install it.

Thanks for the help.

[retiredcaps]

Re: Samsung UN39FH5000FXZA LCD TV power on cycling

Just out of warranty at one year old,

Some credit cards double the original manufacturers warranty. Check yours if you paid by credit card.

[fzabkar]

Re: Samsung UN39FH5000FXZA LCD TV power on cycling

Have you checked for thermal problems with a hair dryer or spray freeze?

Apparently Canada has similar statutory warranty laws as Australia:
http://globalnews.ca/news/1906671/th...ranty-in-sask/

Although many people aren’t aware, statutory warranty rights have been around for 50 years, for issues including durability.

Suppliers are deemed to give minimum warranties known as statutory warranties whenever they sell a new or used consumer product.

The minimum statutory warranties include that:

• the product belongs to the buyer without undisclosed liens or other claims;
• the product is of acceptable quality;
• the product is reasonably durable and fit for the use intended as well as for any specific purpose stated by the retailer;
• the product matches its description and the quality of any samples shown to the consumer; and
• spare parts and repair facilities will be available for a reasonable period of time.

Here in Australia a TV that only lasts 1 year would be deemed to have failed to meet reasonable expectations of durability. This means that the supplier is bound by law to rectify the problem at no charge to you.

BTW, the statutory warranty is mandated by law. The manufacturer may or may not provide an additional voluntary warranty, but the statutory warranty always takes precedence.

[Surrey]

Re: Samsung UN39FH5000FXZA LCD TV power on cycling

A locally sourced main board solved the problem, thanks for the help.