Smd diode D640

[woodman45]

I have repaired an Emerson LC320em2 before with a repair kit for power supply and I have another one that I'm working on.
I'm hoping someone can help me with the smd diode on D640
I tested diode in circuit on continuity mode of dmm & it beeps continuously.
Does this mean it's shorted? I have the old smd diode that I replaced on the other Emerson I repaired & it has the same out come with same test on dmm.
If any one could give some direction on how to properly test this & maybe some other components of this board I would greatly appreciate because I would love more about how to properly test & diagnose other than throwing parts at it.

[woodman45]

Re: Smd diode D640

Here's some pics of the board I couldn't post multiple pics for some reason.

[CapLeaker]

Re: Smd diode D640

D640 that's where the trouble starts... there is more wrong with it yet! So read this: https://www.badcaps.net/forum/showth...hlight=emerson
btw your diode is shorted. But sometimes things measure a short in circuit. So always double check the parts out of circuit too!
BTW... replace D640 with a beefier diode in amp and power rating. I used a FR207 as that is what I had on hand at that time but a 3A diode would be better.

[woodman45]

Re: Smd diode D640

D640 that's where the trouble starts... there is more wrong with it yet! So read this: https://www.badcaps.net/forum/showth...hlight=emerson
btw your diode is shorted. But sometimes things measure a short in circuit. So always double check the parts out of circuit too!

Thanks CapLeaker,
I've read as many threads on this board.
Should I start with testing R608 resistor?
I know that I'll end up getting a repair kit any ways but I would like to learn how to test the most common failed components.again all help & suggestions are greatly appreciated.

[CapLeaker]

Re: Smd diode D640

Sure you can start with R608. Resistors can change values (higher than they should be or open circuit), diodes fail short, same as mosfets. Some parts may measure a short in circuit, so you have to lift a leg or take it totally out and measure it again. It's easy to spot an open resistor, but it is much trickier to find one that changed in value, as you would have to compare the measured resistance with the colour coding to the body of the resistor. Good luck!

[woodman45]

Re: Smd diode D640

Thanks again for your advice.in the pic would you recommend this diode?

[CapLeaker]

Re: Smd diode D640

I can't remember anymore exactly what voltage rating the original diode d640 was. However that's diode in your last post isn't strong enough in your last post. I thought something like a s320 or mbrs3200, 3A 200V Shottky. Iam trying to remember, but I think the original d640 was a 2A 100V?

[woodman45]

Re: Smd diode D640

Update: I got power supply kit,as I removed parts from the board I discovered that the diodes on d604,d607 were shorted as well as the d640.also the 2 cement resistors were shot and I replaced as well.
The tv power right up after I replaced all new parts.Thanks for the advice & help CapLeaker.

[woodman45]

Re: Smd diode D640

Also here's a pic of the kit I used

[CapLeaker]

Re: Smd diode D640

Thanks for the follow up!

[woodman45]

Re: Smd diode D640

Here's a service manual in case there's no one posted in other threads.

[woodman45]

Re: Smd diode D640

Also here's a pic of the cement resistors that I replaced & the way to test them is simply by continuity.if they have continuous continuity there good if not there dead & should be replaced