Philips 40pfl7505d/f7 clicking noise

[landyboy]

I picked up a Phillips LED that all it does is make a repeating clicking noise when plugged in. If I unplug the main board connector (circled in yellow) the clicking stops. I found a fuse circled in red in the picture that was blow. Replaced the fuse and it blew as soon as I plugged it in. I unplugged the main board replaced the fuse and plugged the set in and the fuse did not blow and I had 5v standby on the PSU. As soon as I plug in the main board the fuse will blow.

[tom66]

Re: Philips 40pfl7505d/f7 clicking noise

There are relays on the SMPS, once the main board sends the power-ON command, the relay clicks on and the fuse "sees" a short, blowing.
I would check all FETs on the primary for shorts, you'll probably find one or two bad.

[landyboy]

Re: Philips 40pfl7505d/f7 clicking noise

Thanks,
Just to be sure before I desolder the fets, the fet's circled in blue are the primary side fets correct?

[tom66]

Re: Philips 40pfl7505d/f7 clicking noise

Those are them (although left hand one is for 5V standby and so should be OK), plus there are two others under the other metal heatsink on the primary side, test those too.

No need to desolder FETs for now. Just check for shorts. If you find shorts then desolder them to confirm the diagnosis.

When replacing the FET always replace the driver IC, resistors, and diodes on the gate tract of each FET to prevent repeated failure.

[landyboy]

Re: Philips 40pfl7505d/f7 clicking noise

Just a follow up, three of the fets were bad. I couldn't find them to replace. I did find the entire board cheap. The new power supply did the trick. Thanks

[tom66]

Re: Philips 40pfl7505d/f7 clicking noise

Out of interest, which three were bad?

[landyboy]

Re: Philips 40pfl7505d/f7 clicking noise

Circled in Blue. All three had a Source to drain short.

[tom66]

Re: Philips 40pfl7505d/f7 clicking noise

One is a diode, probably only the two on that small heatsink were bad.

[landyboy]

Re: Philips 40pfl7505d/f7 clicking noise

What generally causes these to go bad? Lightning? Power surge?

[tom66]

Re: Philips 40pfl7505d/f7 clicking noise

Statistically random failure due to limited operating lifetime, if they run hot they will fail faster, ALL electronic components have a lifespan.

If a component has a 100,000 hr MTBF (mean time between failures) then you can in fact expect a group of 100 of them to fail on average every 1,000 hours.

[sspoonmann]

Re: Philips 40pfl7505d/f7 clicking noise

Did you figure this one out. I have same 23 blink. Nothing blown on power board that i cant measure. power board does have 2 terminals for troubleshooting. ps-on and bl-on. I shorted both and got good back lighting. all hooked up I get ps-on from main but no bl-on like main is waiting for a trigger. also with back lighting on there is no osd or video just blue while it goes through the 23 blink to click. any help thanks.

[sspoonmann]

Re: Philips 40pfl7505d/f7 clicking noise

no bl-on . replace main solved

[deciphe]

Re: Philips 40pfl7505d/f7 clicking noise

I have picked up a simular tv and tho i can find a complete board i usually rather fix then just replace parts. The fets look unmarked from what i can see what is the best way to determine the specs so i can get them so i can attempt the repair.

thanks

[rjamesp75]

Re: Philips 40pfl7505d/f7 clicking noise

I know this is and old forum but I just got the same tv and all it does is blink 23 times click and blink 23 times again. What is the problem? Main board?

[budm]

Re: Philips 40pfl7505d/f7 clicking noise

Did you do any visual inspection of all the boards? Voltages checking on the power supply board?
Pictures of YOUR board will also help.

[demonspride]

Re: Philips 40pfl7505d/f7 clicking noise

I got this problem too, the fets you said where probably bad on the smaller heatsink, replaced them with new one of exact model same problem, replaced all the diodes and resister compnesnt/gates etc to and from them too, no dice, i plan on ordering a new board, just didnt want to wait. any other guesses?