Philips 46pfl5505d/f7

[Agent24]

Re: Philips 46pfl5505d/f7

Looks like D951 is the one that's shorted. See how the meter shows a very low reading in both directions?

What you are looking for is the forward voltage drop (average is 0.6v or 600mV) in forward bias (that is, the positive lead connected to anode and negative to cathode) and in reverse bias you should have no voltage drop at all, or rather, an open circuit (your particular meter shows this, or other out-of-range condition as a "1" on the far left of the display).

What your diode shows is 2mV voltage drop both directions which means the diode is now acting much the same as a piece of wire.

[budm]

Re: Philips 46pfl5505d/f7

This is D951

Bad. You should put in new battery for you meter.

[krygods]

Re: Philips 46pfl5505d/f7

Diode says SB260 on it.

[budm]

Re: Philips 46pfl5505d/f7

Schematic shows as SB260.
https://cdn.badcaps-static.com/pdfs/...778b06be8a.pdf

[krygods]

Re: Philips 46pfl5505d/f7

Anything I can find one of these in or is it easier to just order one and wait for it to arrive?

[Agent24]

Re: Philips 46pfl5505d/f7

For reliability it might make more sense to upgrade to a single, higher current diode and install that in the unused D952 space. (If one suitable exists)

[budm]

Re: Philips 46pfl5505d/f7

The spec recommends 0.375" lead length on each side for it to handle If rating based on Ta of 25C.
It looks like the leads are cut too short, I would replace both of them and keep the lead length as long as possible. The bad thing about using two diodes in parallel is that the Vf should be matched otherwise one will conduct more current than the other.

[krygods]

Re: Philips 46pfl5505d/f7

So it makes sense to buy a good quantity of them and find two that are closely matched?

[CapLeaker]

Re: Philips 46pfl5505d/f7

I don't really like installing 2 diodes in parallel, I rather like to upgrade the single diode with something bigger and heavier... I't doesn't have to be a SB260, as long the replacement has at least the same voltage and current capabilities, is a fast switching schottky diode.

[budm]

Re: Philips 46pfl5505d/f7

I myself would use TO-220 case type DIODE mounted on a heatsink.

[krygods]

Re: Philips 46pfl5505d/f7

I like the idea of upgrading to prevent future failure. What is required to upgrade to a single diode? what diodes are removed, where does the single one go? Do I have to jump any traces due to the missing diodes?

[CapLeaker]

Re: Philips 46pfl5505d/f7

you have to keep ZD951, that is your overvoltage protection. But D950 and D951 you can take out and put a single heavy diode in its place. Depending on the casing style diode (lets say TO-220) you have to add a heat sink.
The SB260's are 2 amps, 60V each. So whatever diode you chose has to be at least 4 amps, 60V, since they were two in parallel. So you don't want that to happen again, put an 5 or 8 or 10 amp, 80 to 100V schottky into it. Where does it go? D950 and D951 have to be removed and you could use either D950, D951 or D952 to put the new large single diode in.
So a SB5100 (5A/100V), a SB580 (5A/80V) axial or a 8TQ100 (8A/100V) TO-220 with heat sink etc. I am sure you get the idea now.
No, you don't put any jumpers.

[krygods]

Re: Philips 46pfl5505d/f7

-

[krygods]

Re: Philips 46pfl5505d/f7

I have an NTE573 60V 5A, is this suitable for as a single diode or does the voltage need to be higher?

[budm]

Re: Philips 46pfl5505d/f7

That should be OK, but you must keep the legs length as long as possible ans noted in NOTES 1 of the spec sheet (but it is not likely that the ambient will be at 25c). You can use it and see how hot it gets.

[krygods]

Re: Philips 46pfl5505d/f7

Okay so I installed the diode. TV turned on and functioned properly. I turned the TV off and now when I try to power it on the White LED blinks 21 times pauses for a second and continues to blink 21 times over and over until the power is unplugged.

[CapLeaker]

Re: Philips 46pfl5505d/f7

Start a new diagnosis. Check all voltages, force on the PSU without the main board etc.

[krygods]

Re: Philips 46pfl5505d/f7

So I re-checked all the diodes, all test good. I checked for voltage at CN2 here is what I've found. No voltage at Pin 9 or any other Pin at CN2, except Pin 11 at CN2 shows -6VDC.

[CapLeaker]

Re: Philips 46pfl5505d/f7

This doesn't make sense. Pin 9 is your 5.3 STBY and pin 11 is GND. So if pin 9 is zero Volts, nothing would work at all... no blinking led, nuttn.

[budm]

Re: Philips 46pfl5505d/f7

Must be measurement error.