Help identifying blown part on Sony BDP-S590 Blu-Ray player.

[trnkyit]

I need some guidance. 

I really don't know where to begin.  I have never tried to fix anything before, but as I age, I'm getting tired of replacing hardware.  I swear this stuff is laughing at me, no, taunting me, and before I take a hammer to it, I'll give it a go and maybe learn something. 

Anyway, I have a few items around here in a constant state of laughter...


This is a Sony BDP-S590 Blu-Ray player that was most likely in a lighting strike.  The attached image is the power supply board with the 110 cord attached.  I've noticed a blown " transistor "?  At least I think its a transistor, as it has three leads....   Okay I don't know what it is.  Searching the Intertubes has proven very useful.

How does one figure out what that is?

I'm sure there are some threads that show you to to do trouble shooting like this, but I haven't clicked on one...


Corey

[theatrus]

The only semiconductor in this picture is the one labeled IC201 - is that the part in question?

Any chance of reading the markings on it? The SOT-23 won't have much. The pinout labeling (nice!) or A/K/R is also interesting, which might indicate a reference.

[trnkyit]

Yes, the IC201 is the blown part.  I can't read anything on it. 

On a different board there is another similar sized semiconductor labeled  " K-1 ".   What are the odds they are the same thing?

[theatrus]

Yes, the IC201 is the blown part.  I can't read anything on it. 

On a different board there is another similar sized semiconductor labeled  " K-1 ".   What are the odds they are the same thing?

Ok, I see it appears to actually be split in two. This is concerning, especially if it is after the transformer. Its likely this is not the only dead component, just the most visible. Can you trace out where, roughly, it lies in the circuit? There do the labeled K/A/R nets go?

The SOT-23-3 package is used from everything from diodes, to BJTs, to FETs, to references, and even sensors (1 wire).

[trnkyit]

Here are some expanded shots.  Front and Back of the board.
The blown IC is after the transformer I believe.  Well its on the ' secondary ' part of the board so I'm assuming that's after the transformer.

I'll do some traces and post tomorrow my results. 

Thanks for helping.  I realize it can get frustrating with newbies,  as were slow and stupid.




But hey, I've already learned how to look up a Z-1 IC.  Its a Fairchild Zener Diodes 22V 0.5W

[amyk]

I'm 99.999% certain it's the TL431 for the control loop, given the K, A, and R designations, and the fact that tracing the schematic (attached) reveals the standard circuit for one. According to the resistor values the output voltage of this PSU should be 2.5V * (82k + 22k + 27k) / 27k = 12.1V which also makes sense.

[Rasz]

start by  connecting 12V directly to the BD player and checking if its alive, no point fixing this psu if player got zapped by lightning

[Kjelt]

A warning before you get frustrated, devices that suffered a lightning strike usually have a lot (and I mean a lot) components damaged depending on the impact of the lighting and the way through the device.

[trnkyit]

I'm 99.999% certain it's the TL431 for the control loop, given the K, A, and R designations, and the fact that tracing the schematic (attached) reveals the standard circuit for one. According to the resistor values the output voltage of this PSU should be 2.5V * (82k + 22k + 27k) / 27k = 12.1V which also makes sense.

Amyk,  that looks spot on.  The front side of the board actually says UNSV 12V.  The chip being a Unisonic.

How did you come up with this?  Experience? Or were you able to figure out the source from other components on the board?  Curious.

[trnkyit]

start by  connecting 12V directly to the BD player and checking if its alive, no point fixing this psu if player got zapped by lightning

Rasz, keeping it newbie, how do I figure out the Amps required ?   I looks like pins 1,2,3 are + and pins 4,5,6 are ground.

[trnkyit]

A warning before you get frustrated, devices that suffered a lightning strike usually have a lot (and I mean a lot) components damaged depending on the impact of the lighting and the way through the device.

Lightning... Yea I understand its a long shot, but, there's still much to learn from this exercise.
I would have thought, I would see more damage everywhere, but this is the only spot I can see.  Everything else looks great.

[Rasz]

start by  connecting 12V directly to the BD player and checking if its alive, no point fixing this psu if player got zapped by lightning

Rasz, keeping it newbie, how do I figure out the Amps required ?   I looks like pins 1,2,3 are + and pins 4,5,6 are ground.

this psu does 5A max
http://www.mitsumi.co.jp/latest/Catalog/pdf/power_srv_e.pdf

old PC power supply will do

[trnkyit]

start by  connecting 12V directly to the BD player and checking if its alive, no point fixing this psu if player got zapped by lightning

Rasz, keeping it newbie, how do I figure out the Amps required ?   I looks like pins 1,2,3 are + and pins 4,5,6 are ground.

this psu does 5A max
http://www.mitsumi.co.jp/latest/Catalog/pdf/power_srv_e.pdf

old PC power supply will do

Rasz,

Thanks man!  I tried your suggestion and it works!   

So now I'll focus on trying to get that damaged part and see if I can fix the power supply.

[theatrus]

Cool!

I'd go through and verify the following on the power supply:

- capacitors are ok
- power semiconductors aren't shorted
- resistors are ok
- isolation from primary to secondary remains intact

Having just the reference explode is a bit unusual

[trnkyit]

Cool!

I'd go through and verify the following on the power supply:

- capacitors are ok
- power semiconductors aren't shorted
- resistors are ok
- isolation from primary to secondary remains intact

Having just the reference explode is a bit unusual

Theatrus,

Thanks for the checklist.   This should keep me busy.  I just wonder if I'm going to be able to find the blown part.  Maybe I can substitute for something else... 

[theatrus]

If it's actually a TL431 (seems likely), they are everywhere.


http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=ZTL431AFFCT-ND

[amyk]

How did you come up with this?  Experience? Or were you able to figure out the source from other components on the board?  Curious.

Just some experience with designing, modifying, and repairing SMPS. The TL431 is used in almost all the ones that do secondary-side sensing with feedback through an optocoupler, and the circuit has little variation; here's another one: http://www.electronicrepairguide.com/images/schematicsdiagram.jpg

Also, when you first test it, make sure to power it up with a small dummy load, preferably a power resistor - this is so that you can verify the output is regulated at the correct voltage and not risk further damage to your real load. Defective components in the feedback circuit can cause the output voltage to rise extremely high.

[SeanB]

I know, a nominal 5V supply with dead caps on the secondary side I checked with a resistor load, and it was happy to deliver over 50V to it. Replaced the caps, and it was 5V again. Too bad for the hotel that had to buy a new room card writer, it was well cooked. I did suggest the new one have a 6V8  5W transorb on the input side as added security.