Samsung TV

Hi Baron

I don't have access to service info for that tv unfortunately, but if it's like most LCDs, the dead set symptom is mostly down to psu trouble, and most are not that difficult to sort without schematics. Often, it's just caps, as I'm sure you've seen mentioned on here many times. You will often find the voltages marked on the psu boards. By connectors is a good place to look. Typically, there will be a standby supply of 3v3 and/or 5v. The main switched rails are usually some or all of 3v3, 5v, 12v, 24v for the backlight supply, and 33v for the tuner. Occasionally, the odd negative rail.

If it does come down to psu, and you can't fix it, a replacement board is available here

for a very reasonable price. In the meantime, I will ask my mate who does a great deal of LCD tv repairs, if there is anything common on that model that he knows of.

Arfa

Have you checked SAM"S PHotofacts?

Arfa Daily Inscribed thus:

Hi Arfa, Thanks. I did pull the back off today and as you say the voltages are marked on the PSU PCB. All the ones that I could identify I probed without finding one that wasn't correct.

I did note that the red led in the middle of the power button seems to have a weird flash sequence, so I suspect that its some kind of fault code, a bit like the BIOS beep codes.

Once again I'm grateful for any help I can get. Many Thanks.

snipped-for-privacy@att.net Inscribed thus:

No ! But I will. Thanks for the pointer.

Arfa Daily Inscribed thus:

Hi Arfa, It was running just fine, then without any warning the display went off and the little red standby LED in the middle of the button started flashing. 3short, delay, 1long, off, delay then the sequence starts again.

No I haven't disconnected the backlight panel. There seems to be 6 or 8 inverters on a separate panel running vertically up the left side, viewed from the rear. There is a single multiway cable connecting the inverter panel to the PSU board. The backlight panel is under a metal screen, making it hard to see underneath without removing fairly substantial metalwork.

Thanks:

It's only the plug to the inverter board that you need to remove. From the described symptoms, I doubt that the problem is going to be that, but it is common for backlight inverters to fail on all makes of LCD TV, and the excess load then placed on the PSU's 24v rail can cause some odd and bizarre startup problems, depending on how and where the supply monitors it's output voltages and the current draws on the various rails. Normally, although the connector to the inverter board has a lot of wires, most of them are just paralleled-up +24v and gnd. There is often a control wire also.

I was unable to check further with my mate today, as he is off with man-flu. The other guy in the shop is more computers than TV, so doesn't know a lot about TV faults. Arfa

Arfa Daily Inscribed thus:

Hi Arfa,

Yes I did disconnect the cable from the main board to the inverter board where it connects to the PSU board. It made no difference ! :-(

I've a sneaky feeling that the flashing sequence of the power LED is trying to tell me something, but I haven't been able to find out what.

I'm afraid thats the camp I'm in. 35+ years ago TV's were much more understandable, read simple, to understand.

Your help is very much appreciated. Thanks:

PS. At least the old 28" Bush and digibox still work... (*)