HP LCD 2009F No Power Almost Done. but After 15 mins Backjob Always Short this Diode

[lorins_core]

Good Day to All Forum mates

I have HP LCD 2009F No power.

I trace the Problem i found D587 here the Image

Credit to armand666 Picture


i Edit and i Marking Arrow

I replace Already. i test for Burn-test. after 15 mins. turning off the no power Again.

i have a Stock these diode SR520. i Installed a New one. After a 30 mins Turn Off Again Same Problem.

Any One can help Me to trace the this and Why Diode Always Broken.


Update.
i Experiment Put and installed SP1060.
3 pin Diode
also Broken Around 1 hour.

Pin 1-2 Shorted
Pin 3-2 Good.




TIA

[budm]

Re: HP LCD 2009F No Power Almost Done. but After 15 mins Backjob Always Short this Di

What is the ORIGINAL diode P/N?
We need to pictures of the whole Bottom side of the board too.
BTW, those two diodes look to be connected in parallel, so only ONE of them failed?

[R_J]

Re: HP LCD 2009F No Power Almost Done. but After 15 mins Backjob Always Short this Di

I checked a different picture and they are in parellel, likely the other diode is damaged.
I would try something like SB560
Voltage seems low on SR520

[lorins_core]

Re: HP LCD 2009F No Power Almost Done. but After 15 mins Backjob Always Short this Di

What is the ORIGINAL diode P/N?
We need to pictures of the whole Bottom side of the board too.
BTW, those two diodes look to be connected in parallel, so only ONE of them failed?

Q: no1. What is the ORIGINAL diode P/N?
A: it is 2 pcs of SR520

Wait i captured again.

Anyway I have A question for now. way D857 Always Short if i Install new and Good SR520 Diode?

[lorins_core]

Re: HP LCD 2009F No Power Almost Done. but After 15 mins Backjob Always Short this Di

I checked a different picture and they are in parellel, likely the other diode is damaged.
I would try something like SB560
Voltage seems low on SR520

i Update...
I replaced the both Diode
For now I try to Installed SP1060 diode

Oh yes. have already Power up But only 3 Hours Used Only same Problem.

Backjob....

Pin 1-2 Shorted
Pin 2-3 Ok

Here's the Data Sheed of Diode : https://cdn.badcaps-static.com/pdfs/...241e775e6b.pdf

[lorins_core]

Re: HP LCD 2009F No Power Almost Done. but After 15 mins Backjob Always Short this Di

i Update...
I replaced the both Diode
For now I try to Installed SP1060 diode

Oh yes. have already Power up But only 3 Hours Used Only same Problem.

Backjob....

Pin 1-2 Shorted
Pin 2-3 Ok

Here's the Data Sheet of Diode : https://cdn.badcaps-static.com/pdfs/...241e775e6b.pdf

[budm]

Re: HP LCD 2009F No Power Almost Done. but After 15 mins Backjob Always Short this Di

Did the diode get very hot after running for a while before it failed in shorted out mode?

[momaka]

Re: HP LCD 2009F No Power Almost Done. but After 15 mins Backjob Always Short this Di

From the silkscreen on the board, you can see these two parallel diodes are installed in a spot where there was supposed to be a heatsink with a TO-220 rectifier mounted on it. If I had to guess, the manufacturer probably cheaped-out on the design and used the SR520 diodes, which may not be adequate, and over time, as components age, there may be something that is killing them.

Make sure the output caps are good - if you have a capacitance + ESR meter, pull them out and check them. Otherwise, replacing them with new (good Japanese quality ones) might be the only safer way to go.

Next check the resistor and ceramic capacitor right next to those SB520 diodes - I think this should be the low-side (output) snubber network (please upload a picture of the solder-side of the board so that we can check). If if is, and that ceramic cap is leaky, that could well be the reason why those diodes are blowing.

Speaking of the SB520 diodes... their reverse (blocking) voltage rating (20V DC) seems really really low. I suggest going with 45V or higher rated Schottky diodes. Better yet, remove those SB520 diodes and grab something like a MBR2045CT, MBR2060CT, or BYQ28E (TO-220 rectifier) to put in place of them. Really, any 10-20 Amp schottky rectifier with a 45V or higher rating would be recommended here. If you have a small piece of aluminum to make a heatsink for the TO-220 part, that would be even better.

Lastly, check the output voltage of the PSU once you get it fixed again, to make sure it is what it should be.

[lorins_core]

Re: HP LCD 2009F No Power Almost Done. but After 15 mins Backjob Always Short this Di

From the silkscreen on the board, you can see these two parallel diodes are installed in a spot where there was supposed to be a heatsink with a TO-220 rectifier mounted on it. If I had to guess, the manufacturer probably cheaped-out on the design and used the SR520 diodes, which may not be adequate, and over time, as components age, there may be something that is killing them.

Make sure the output caps are good - if you have a capacitance + ESR meter, pull them out and check them. Otherwise, replacing them with new (good Japanese quality ones) might be the only safer way to go.

Next check the resistor and ceramic capacitor right next to those SB520 diodes - I think this should be the low-side (output) snubber network (please upload a picture of the solder-side of the board so that we can check). If if is, and that ceramic cap is leaky, that could well be the reason why those diodes are blowing.

Speaking of the SB520 diodes... their reverse (blocking) voltage rating (20V DC) seems really really low. I suggest going with 45V or higher rated Schottky diodes. Better yet, remove those SB520 diodes and grab something like a MBR2045CT, MBR2060CT, or BYQ28E (TO-220 rectifier) to put in place of them. Really, any 10-20 Amp schottky rectifier with a 45V or higher rating would be recommended here. If you have a small piece of aluminum to make a heatsink for the TO-220 part, that would be even better.

Lastly, check the output voltage of the PSU once you get it fixed again, to make sure it is what it should be.

Thanks For Advice Master. I ll try later.