Samsung LN40A530P1F Blinking LED

[Pentium4]

This is our display TV in the lobby at work, has ~14,500 POH. Couple days ago it made a loud monotone static sound, and the picture froze. The receptionist said the power button wouldn't turn it off. Once unplugged, it would not turn back on. The front LED blinks, and when you hit the power button, it does make that beep sound that Samsung TV's normally make.

I unplugged the Tcon board, and it does the same thing.
The NTCs look like they run hot. They both read 3.2Ω when cold, in circuit
Pulled and checked all electrolytic caps, all tested good. Getting 383V DC over both input caps. 5.3V standby reads 5.09V.
Power on/off reads 4.32V
13V reads 12.89V on PSU and on mainboard

Any ideas?

[budm]

Re: Samsung LN40A530P1F Blinking LED

It points out to the main board problem when buttons do not response.
The power supply is getting the PS_ON signal to turn on the PFC Voltage booster otherwise you will not get the 385VDC on the main filter cap.
As to where the problem on the main board is, I don't know.
SJ sells main board repair kit:
http://www.shopjimmy.com/catalogsear...ng+LN40A530P1F

[Pentium4]

Re: Samsung LN40A530P1F Blinking LED

Thanks for the response budm. Not sure I have the skill to replace those chips. If it's definitely the mainboard, I see a few for sale on ebay. My shop is just going to buy a new TV, so they said I can have this one if I fix it

Also worth mentioning: On the CNI803 plug, Inverter on/off only gets 0.040V DC on the PSU and mainboard. PWM DIM fluctuates between 4.07V and 4.52V. DET_5V reads 5.08V

[Shinju]

Re: Samsung LN40A530P1F Blinking LED

I have had a few of these mainboards fail, I did manage to get one limping again by doing a reflow as the CPU was not put on very well.

The panel is still working, every once in a while when it hasn't been used when powered on the screen is scrambled and you hear a squeal after a few self power cycles it comes back fine.

I live with it as its a TV in the work out room

[Pentium4]

Re: Samsung LN40A530P1F Blinking LED

How did you figure out that the CPU on the mainboard was bad?

Is it still possible that the problem lies with the PSU?

[Shinju]

Re: Samsung LN40A530P1F Blinking LED

I applied pressure to it and it came on perfectly.

[Pentium4]

Re: Samsung LN40A530P1F Blinking LED

Gotcha. I guess it wouldn't hurt to hit it with the heat gun

[dominicMc]

Re: Samsung LN40A530P1F Blinking LED

If you're looking for parts, I might be able to help....

[Pentium4]

Re: Samsung LN40A530P1F Blinking LED

Oooo, thank you dominic! I may...I just started looking at this thing again. All I did was reseat all the cables on the mainboard, and it powered on normally. The picture was steady and almost normal for about 10 seconds:


And then I plugged it in via VGA, and the picture was flashing and rolling up and down:


After about 30 seconds, the picture became readable, but was shaky:


Putting pressure on the mainboard CPU made no difference. The thing will run as long as I let it, and hitting the power turns it off now, it makes the noise it's supposed to, and goes into standby with a solid light like normal. Does this help narrow it down at all?

[Pentium4]

Re: Samsung LN40A530P1F Blinking LED

Okay so I got this thing working flawlessly now. I reflowed the CPU on the mainboard. This got it working well, but after 15 minutes would start having the previous symptoms. So I recapped the entire power board with much lower ESR caps, and put a good sized heatsink on that chip next to the mainboard CPU under the cable going to the Tcon board, now it isn't having any issues even after hours of being powered on playing 720p

[veikra]

Re: Samsung LN40A530P1F Blinking LED

LN40A530P1Fxzc it's a c but samsung would probably give me the finger, being Im in canada

I have red blinking led. it responds to remote signals and it beeps when you press power on the tv. It doesnt turn on.

I checked psu voltages, they are within specs and I can turn on the psu including backlight . Changing a few caps got rid of the high pitch sounds of the psu.

I replaced c102 and C131 on the main board with used ones I had. It made the optical out light comes on. It stays on for 25 sec, goes off, then on from another 25 seconds.
Something seems to work in there.

pressing on the cpu does nothing. Heating the caps of the psu nothing either

Any ideas?

[Pentium4]

Re: Samsung LN40A530P1F Blinking LED

I believe it's the sound chip that is failing. That, or the CPU on the mainboard.

I think this is the culprit:

[veikra]

Re: Samsung LN40A530P1F Blinking LED

im thinking of removing it and see if the thing boots up....in the meantime, I put a toshiba board in the tv and got it working. Some kits are sold with that audio chip and the one underneat near the 2 capacitor I replaced. Need to order those and try

[Pentium4]

Re: Samsung LN40A530P1F Blinking LED

Interesting, what was the model of the Toshiba board?

[veikra]

Re: Samsung LN40A530P1F Blinking LED

Interesting, what was the model of the Toshiba board?

SRF40T VTV-L40613 from Toshiba 40E220U

You can check the video on my channel https://www.youtube.com/watch?v=qwNro0Y_EI8

but it was a little more involved than just the mainboard. I put the toshiba power board in there, added a relay to turn on the samsung powersupply from the toshiba's 24V rail so I wouldnt have 2 cords and having to manually turn off backlight

The samsung's tcon board works with that board, despite the toshiba 40E220U tcon having a separate backlight dimmer connector, the samsung doesnt.

So no backlight control, full bright.

[kevinm34232]

Re: Samsung LN40A530P1F Blinking LED

I have worked on many, many of these, and usually when you just get relay clicks every 20-25 secs it is something with the main CPU (I've been guessing bad solder) as reflow usually temporarily helps. It's not the audio IC. The voltages are usually all good as well when having this symptom.

LN40A530P1Fxzc it's a c but samsung would probably give me the finger, being Im in canada

I have red blinking led. it responds to remote signals and it beeps when you press power on the tv. It doesnt turn on.

I checked psu voltages, they are within specs and I can turn on the psu including backlight . Changing a few caps got rid of the high pitch sounds of the psu.

I replaced c102 and C131 on the main board with used ones I had. It made the optical out light comes on. It stays on for 25 sec, goes off, then on from another 25 seconds.
Something seems to work in there.

pressing on the cpu does nothing. Heating the caps of the psu nothing either

Any ideas?

[veikra]

Re: Samsung LN40A530P1F Blinking LED

You are right, I have removed the audio chip with no difference in behavior.
I am considering reflow of the cpu

there is no relay clicking. the optical does a 25 sec cycle. Nothing click, red light flashes.