Re: Samsung LCD Power Board turning on and off.

I would have replaced 'em all but did not have the 3300uF cap. They measured ok though, and the TV boots up nicely this morning too. I have some cap values on order now and will replace the rest if the tv comes back to me :-)

Re: Samsung LCD Power Board turning on and off.

I worked on a Samsung LE32A465 from my friend which turned on and off randomly. The power board is BN44-00214A and it had one bulging capacitor, the 2200uF / 10V connected to the stand by circuit. Its ESR value was actually not as bad as I thought, about 0.6 ohms. Replaced it with Panasonic low-ESR type. Other caps measured good, close to zero ESR. The TV turned on, and stayed on for a few hours without problems so I gave it back yesterday.

Today it didn't start again, and I found this thread about the dried up solder...

Re: VierwSonic VX922 and VX724 Bad CapXon

I repaired yesterday a VX724 which was salvaged from the company dumpster.

I have to say that at first the inverter board look beyond repair since the large 100uF / 400V cap had leaked badly and the board was also pretty red due to overheating. All other caps were also bulging. I immediately suspected that the switcher IC (SG6841S) could be damaged because of the primary side cap failure... Strangely enough not even the fuse was blown and all semiconductors tested ok. Replacing all small caps with new low ESR ones and using...

Re: DELL 1907 FPT power supply



Hi Alexanna, if you don't have access to a scope you can try using a multimeter with Hz measurement capability! Expect the inverter frequency to be between 20-70 kHz. You can touch the circuits on the primary side but may fry your multimeter on the secondary (HV) side. Or you can use the probes as an antenna like in this example:

[url]http://www.fonerbooks.com/test.htm[/url]

I have to try this with my Fluke 117 at home too Re: DELL 1907 FPT power supply<br />...exanna, if you...

Re: DELL 1907 FPT power supply



My monitor is alive! I transplanted the CCFL lamps from the Acer monitor, and now the Dell monitor works perfectly. One of the original lamps glass was broken, and I could smell ozone when testing it. The Acer lamps fitted almost perfectly, I did'nt even need to solder anything. I just moved the lamps and cable assemblies into the lamp holders. Thanks again for your encouragement!

Now I have a working power supply & inverter board for Acer AL1716 if anyone wants it. Sadly I cracked the LCD a bit while putting it back...

Re: DELL 1907 FPT power supply



Thanks for the tip! I'll try to move the wires a bit and see if there is any change to the noise. Can you suggest an easy/safe way to resolder the CCFL wires? I've got no prior experience on dismantling LCDs, but am willing to take the risk in this case Also, is it safe to test the inverter without all tubes connected, like one at a time? If the safety circuit kicks in without a load then it doesn't work...

By the way, I read the inverter driver chip to be BD6D24 or BD6D2H with a production code P607. It's really hard...

Re: DELL 1907 FPT power supply



I would like to add that there is an audible 'white' noise which seems to come from one corner of the LCD panel when the monitor is turned on. I tried to localize it and it doesn't seem to come from the power supply/inverter board. The sound ends when the backlight is switched off in about 2 seconds after powerup.

Is it possible for the CCFL tubes to emit noise? I'll try to switch the inverters and backlights from the Acer monitor mentioned above tonight, and see where the real culprit is...

-- Jussi...

Re: DELL 1907 FPT power supply



Hi! I have exactly the same board here with similar symptoms. It's from a Dell 1707fpt I rescued from the dumpster recently I checked all power supply and logic board caps with an ESR meter and didn't find anything too suspicious, all were 0.1-0.3 ohms. I replaced all the inverter caps anyway but there was no change. Next I'll have to try with good lamps from another monitor I rescued (Acer AL1716A, has problems with VGA syncing but steady backlight ).

Is there a schematic of the inverter on these Dell boards? There...