Working on a Maxent MX-42HPM20 and had a thought that I think merits a separate thread.
My thought process is as follows:
My Plasma TV seems to have a bad ZSUS IPM (unconfirmed) and maybe a bad YSUS also (no reason to think this yet), and while doing research on these IPM's I get the impression that it's a common failure, and while there isn't much consensus on what causes these expensive IPM's to go bad, most people assume that it's heat, as they run hot, and there's this (11mm thick) thermal pad behind them. You'd think it was there for a reason. They get hot.
When I pulled my ZSUS board off, there was an obvious trace of liquid emanating from the pad, and some of the material from the pad stuck to the IPM, and it was almost "glued" to the IPM. I interpret all of this as a breakdown of the thermal pad material. So, while doing research on replacing this pad, maybe with a larger and more effective pad (it's too small, IMO, 19mm x 41mm x 11mm (thick), and it could easily be twice that large, or even larger), I note that a lot of the thermal pads listed by Digi-Key contain the words "Aluminum Oxide" in the description, which seems appropriate because my bad is unusually heavy, dark grey and it might have some aluminum oxide in it, and then I had the idea.
The idea is that, what if these pads work okay when they are new, and are not conductive, or capacitive, or whatever, but after (in my case) 7+ years the material breaks down (seeping liquid, glues itself to the pc board and material rips away when pad is removed), the electrical characteristics of these pads change and THAT is what is killing-off these IPM's. I've read at least one anecdote that the ZSUS IPM fails after replacement, and that would make sense if it is the pad that is killing them off.
The idea of forcing the pins of a (small) mass of electrical components into a solid material made out of aluminum oxide seems highly counter-intuitive to me. You wouldn't mash a flat piece of metal into the back-side of a pc board; so why would you assume a spongy material filled with aluminum oxide is not going to short, or allow some conduction, or act as a capacitor, or whatever. Cause problems, is what I mean here.
Those are my thoughts. I'd be interested in whether or not I might be on to something, or (due to lack of knowledge) I'm missing something.
My thought process is as follows:
My Plasma TV seems to have a bad ZSUS IPM (unconfirmed) and maybe a bad YSUS also (no reason to think this yet), and while doing research on these IPM's I get the impression that it's a common failure, and while there isn't much consensus on what causes these expensive IPM's to go bad, most people assume that it's heat, as they run hot, and there's this (11mm thick) thermal pad behind them. You'd think it was there for a reason. They get hot.
When I pulled my ZSUS board off, there was an obvious trace of liquid emanating from the pad, and some of the material from the pad stuck to the IPM, and it was almost "glued" to the IPM. I interpret all of this as a breakdown of the thermal pad material. So, while doing research on replacing this pad, maybe with a larger and more effective pad (it's too small, IMO, 19mm x 41mm x 11mm (thick), and it could easily be twice that large, or even larger), I note that a lot of the thermal pads listed by Digi-Key contain the words "Aluminum Oxide" in the description, which seems appropriate because my bad is unusually heavy, dark grey and it might have some aluminum oxide in it, and then I had the idea.
The idea is that, what if these pads work okay when they are new, and are not conductive, or capacitive, or whatever, but after (in my case) 7+ years the material breaks down (seeping liquid, glues itself to the pc board and material rips away when pad is removed), the electrical characteristics of these pads change and THAT is what is killing-off these IPM's. I've read at least one anecdote that the ZSUS IPM fails after replacement, and that would make sense if it is the pad that is killing them off.
The idea of forcing the pins of a (small) mass of electrical components into a solid material made out of aluminum oxide seems highly counter-intuitive to me. You wouldn't mash a flat piece of metal into the back-side of a pc board; so why would you assume a spongy material filled with aluminum oxide is not going to short, or allow some conduction, or act as a capacitor, or whatever. Cause problems, is what I mean here.
Those are my thoughts. I'd be interested in whether or not I might be on to something, or (due to lack of knowledge) I'm missing something.
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