Samsung 59" plasma PN59D550C1F seeking advice on mystery power board issue
I picked up this TV from Facebook Marketplace, original owner described it as "screen went black after a pop" and I hoped to see an obvious fuse or cap to replace. Doesn't seem to be the case, but my experience and electrical knowledge are kind of limited for this.
The power board (BN44-00445A, see attached) turns on and Vs and Va seem to momentarily have power, then they steadily drain to zero over a minute or two as if they're only getting power from capacitors. I've been measuring Vs and Va from the test pads, with and without the other boards connected to the power board and power cycling it with the on/off button, which doesn't change the result. Am I missing something simple here?
I've checked quite a few components on the power board following all the posts and videos I can find online, but I haven't found anything which measured wrong with my multimeter. There are two FETs in the PFC circuit (QP802 and QP804) that seem to be the most common failure, I removed them to test and they looked okay. Is it possible for them to be bad anyways?
This video in particular is good and I followed everything in it (https://www.youtube.com/watch?v=dswtNRiZwN8), his method to check the FETs is at 4:40 which is what I did.
Any and all feedback would be greatly appreciated! The attached schematic is for BN44-00445C, but is nearly identical to the A version I have.
The power board (BN44-00445A, see attached) turns on and Vs and Va seem to momentarily have power, then they steadily drain to zero over a minute or two as if they're only getting power from capacitors. I've been measuring Vs and Va from the test pads, with and without the other boards connected to the power board and power cycling it with the on/off button, which doesn't change the result. Am I missing something simple here?
I've checked quite a few components on the power board following all the posts and videos I can find online, but I haven't found anything which measured wrong with my multimeter. There are two FETs in the PFC circuit (QP802 and QP804) that seem to be the most common failure, I removed them to test and they looked okay. Is it possible for them to be bad anyways?
This video in particular is good and I followed everything in it (https://www.youtube.com/watch?v=dswtNRiZwN8), his method to check the FETs is at 4:40 which is what I did.
Any and all feedback would be greatly appreciated! The attached schematic is for BN44-00445C, but is nearly identical to the A version I have.
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