Need help to id part

[tvtech]

I need new Glasses/Spectacles.

Or a bigger Monitor

Regards,
tvtech

 

[1-3-2-4]

PFC IC doc

https://www.electro-tech-online.com/custompdfs/2013/08/r03ds0026ej0400_r2a20113a.pdf

 

[throbscottle]

Did you check for a low resistance path from pin 8 to ground? One of those capacitors could be shorted. Try to trace the path back from pin 8 and test every component on the route from it to whatever is supposed to supply its power. Of course, when you've found what that is you should also check that it is providing the necessary voltage. Of course it's possible that the chip itself is faulty. The only way to test if it is in this case is to disconnect pin 8 and see if you then get a voltage on the pad it was connected to. You will have to unsolder and disconnect the pin because it's possible there's a micro via underneath it. Also test if pin 8 is shorted to any of the other pins. It may be easier to unsolder the whole chip. I hope you don't have to resort to this - a failed discrete component is more likely than a failed chip.

From looking at the photo it seems unlikely, but it's worth checking since smd orientation markings can be deceptive, it's possible you are seeing the chip the wrong way up. Check that what you think is pin 6 is actually connected to ground. If it isn't then the dot's at the other end, you just can't see it.

 

[1-3-2-4]

I know the picture should be the other way up, I just had it that way so you could see the board markings

if the chip is bad (hope not) they don't make a replacement.. at least not that I know of..

Also how do you desolderer a chip of this size without making a mess? Not that I'm going to try right now.. I do need to get myself a SMD rework station, I've been putting it off for some months now.

When you say pin 8 to ground I can touch anyplace like the screw for the heatsink right? I'm seeing 11.89 kohm

wait a sec..

OK at IC101 and C116 if I probe one way I get 11.89 kohm but the other way I get 11.77 kohm

 

[throbscottle]

Your isolation transformer (I presume you mean a dc supply here) idea has legs, but there's a couple of caveats. Use a severely current limited supply, since you want to minimise the chance of causing further damage. You should monitor its voltage, as there's a chance something else is drawing too much current, which will show up as a voltage drop on your current limited supply. Even if the chip works, you should think about how you are going to test it since it still may not result in the appliance working - and even if it does you shouldn't consider it a "fix", just part of the fault finding process.

 

[1-3-2-4]

You do have a point

 

[throbscottle]

Ok you've just established there isn't a short between pin 8 and ground. The difference in readings is because there's a semiconductor junction somewhere - like inside the chip itself - a good sign.

Can you identify the supply where the chip gets it's power from? If you can you should check that that is ok, and then everything in-between. It's possible you may be chasing a red herring if the power comes from the main supply, then this pfc circuit isn't your culprit. (I suppose that's another "leg" for your transformer idea).

I don't know enough about smp's or pfc to give any better help without more information.

It's my bedtime now, hope someone else can help meanwhile.

 

[unclejed613]

SG03 is a spark gap, and should read open circuit.

 

[1-3-2-4]

SG03 is a spark gap, and should read open circuit.

It's inline with a inductor but not reading OC so I assume I need to lift a leg off, really does not make any since if it's a spark gap. I assume they are fine because I get voltages on my rectifier.

Ok you've just established there isn't a short between pin 8 and ground. The difference in readings is because there's a semiconductor junction somewhere - like inside the chip itself - a good sign.

Can you identify the supply where the chip gets it's power from? If you can you should check that that is ok, and then everything in-between. It's possible you may be chasing a red herring if the power comes from the main supply, then this pfc circuit isn't your culprit. (I suppose that's another "leg" for your transformer idea).

I don't know enough about smp's or pfc to give any better help without more information.

It's my bedtime now, hope someone else can help meanwhile.

You know I was scrolling down more in the pdf about the PFC and yeah I see junction diagram, and it's what provides my 390VDC I need to start the ballast.. but all that aside i'm not sure how it relates into getting my two voltages I need the most.