[drussell]

Originally Posted by YamahaFreak

Yeah, there is a large black multi-pin unit (assume IPM) under that black heat sink, which definitely has a chunk missing. I don't know how I'd ever get it unsoldered!

Yeah, that is one of the IPM (Intelligent Power Module) or hybrid module or whatever you want to call it. It is just a bunch of discrete components mounted to one substrate without plastic cases on each device to save on cost. Annoying when one FET/IGBT/diode or whatever blows because you can't just easily replace one $2 part but, whatever... Cost reduction and all that. The advantage, though, is you are replacing most of the drive circuitry within it so you don't have to check a bunch of parts that drive the gate of the blown IGBT or whatever... Everything that is likely to blow is in the IPM.

It's not nearly as difficult as it looks. Using solder wick, you just heat each pin, one at a time, though the wick and it will slurp the solder right out. I find it is easier to melt a little real lead/tin solder on each pin first before trying to wick out the lead free stuff they use during assembly. Solder wick is the key, here. If one pin is stubborn just refill it with lead/tin solder and wick it again. It will come totally loose and just lift right out.

I generally desolder using a solder-slurper vacuum tool but on the IPMs it is WAY easier with solder wick. I've done it on-site with an old 33 watt Ungar iron, so it's not like you need state of the art equipment!

Once you desolder all the pins you lift the whole thing out with the heatsink still attached because the screws are from below, mount the new one to the heatsink and solder it back in.

I have been buying my IPMs from a local guy that imports them himself and sells on eBay. I usually pay about $40 each and haven't had a bad one yet or a repeat failure. Many people suggest replacing both of them on the Y-sus board at the same time (one is the drive, one is for energy recovery usually) though I have had good success replacing just the failed one unless I have reason to suspect it was killed by the other or it seems flakey in some way.

Coppel TV repair is well known for supplying thousands of them in the US market with good results. Buying from a reputable dealer that buys quality supplies in bulk means not worrying about them being used pulls from China or something but they are available all over the place, it is a VERY common failure.

I'm wondering if it'd just be easier to replace the entire YSUS board?

EASIER, sure, but where is the fun in that!??

There is a 'VZB' mark near those two film caps, but I'm unsure of where exactly to measure. There is a double-ended arrow pointing both ways next to the right-most cap.

You simply measure the voltage across the cap...
One multimeter probe to one pin and the other probe to the other pin.

That generally always applies to Vscan but Ve/Vzb being across a cap is more unusual, most of the time it is one test point to ground but since this indicates across the cap, across the cap we measure!

I'll check again for panel glow tonight in pitch darkness.

It is certainly possible to have no glow, it just wasn't what I expected.

It doesn't mean the TV is toast or something, especially if the IPM that is blown is the ERC one, that is usually rigged up to feed recovered power back to the Z board's panel bias supply.