Recently inherited a nonworking Samsung LN40C630 with no signs of external damage to either the screen or front and back body.

While this is the first LCD I have worked on, have been taught to check for burnt and broken components and PC boards, and count flashes and beeps when turn unit on/off.

To date I have only plugged the set in and turned it on and off with these results.

When plug in the AC cord the set makes a short musical sound(MS) and the power light(PL) flashes 6x then off.

When turn the set on get shorter (MS) and (PL) stays on but there is no screen light.

When turn the set off get shorter (MS) and (PL) flashes 5x then off.

After opening the back checked the 2 fuses and the front and back sides of the Power Board (PB) and Main Board (MB).

The 2 fuses were OK and I did not notice any burned/broken components or traces on either board. Upper left of MB noticed Switch SW701.

Then removed the MB connector and plugged the AC cord in and the LCD back light came on.

Pushed SW701, reconnected MB and when connected AC cord got 5 power LED flashes and short music, touched power and LED came on and stayed on (no flashes) but no screen came up and the Input Mode and Menu did not work.After ~ 1 minute touched power and got 5 flashes and short music and set turned off.. Also got same results with a DVD player connected to AV2.

Wonder if these flashes are same as PC BIOS "No Boot" beeps?

Appreciate any suggestions!

Thanks

Ken

On Wed, 03 Sep 2014 13:24:45 -0700, KenO wrote:

Recently inherited a nonworking Samsung LN40C630 with no signs of
external damage to either the screen or front and back body.

...snip....
Appreciate any suggestions!

Thanks

Ken


The absolute first place I'd look is at ALL the SMPS capacitors to make
certain their Resr's are as low as they should be.


I had a Vizio that very reluctantly would come on, kind of like yours,
almost but not quite. So, we left it on all the time, keeping all the caps
warm, so everything kept working. We had a power outage! I turned on,
turned off, turned on, turned off, until the heat finally came up enough
that it stayed on, so again never turned it off. until, another power
outage, so bought another.

Checking the caps, some had 1.7 ohms!! heat up with a soldering iron, and
that resistance would drop down to 0.3 ohms no wonder the TV would stay
on, once on!.

Anyway, check those first. standard failure mode on these TV's [my
understanding]

If you're short test equipment to do the resistance check try Bob Masta
DAQARTA v7.50?
Data AcQuisition And Real-Time Analysis
www.daqarta.com

He has a new release that includes an LCR meter! Just use your soundcard.

Hi Robert,

Thank you for the suggestions!

"If you're short test equipment to do the resistance check try Bob Masta DAQARTA v7.50?"

What hardware are you running DAQARTA on?

At this time my Dell Dimension 2350 WinXP only has the onboard audio.

Do you know if DAQARTA v7.60 will work?

Thanks again for your help!

Ken