So a customer brings in a computer today from a few years ago... Asus P5K-VM... It's a G33 motherboard that takes anywhere from a 775 P4 to Core2Quad...
The customer called and said it wasn't working... Now he has it in a pretty tame environment... He uses it to check email. It has a 350-watt Fortron with all Teapo caps (None of which were bulged) and a very mediocre Pentium 4 6xx CPU. This system is never going to go anywhere near the maximum PSU output. I'd be surprised if it was drawing even 150 watts.
No problem I thought... Most likely there are some UCC KZGs in the VRM high as is usual with Asus. Replace them with those famous 8mm Nichicon HMs which I keep some stock of and away we go.
Imagine my surprise when I find out the motherboard has all solid caps, mostly from UCC, a few from Enesol or Apaq or whatever Asus uses.
Odd, I thought... When I cleaned everything in the garage, the PSU looked fine... Teapo usually does well when not stressed, and I have other customers with Teapo FSP PSUs which haven't complained... OK, let's change the PSU with a personally re-capped FSP. NADA!
After fidgeting with this system for a little while, I decided to try a brand new Seasonic S12-II series, which are famed for their reliability and all-Japanese capacitors. Maybe my refurbed PSU wasn't doing it (Eventhough I had tried 4 different PSUs I re-capped).
Same problem. Memory switched in from different system...
No beeps, nothing. Fans are spinning but no signal to screen.
At this point I try a re-capped Asus P5VD2-MX SE. SAME EXACT SYMPTOM!
Now I know that the problem with these boards are the shoddy transistors Asus uses. The P5K-VM used the infamous Taiwanese NIKOS brand FETs, and I couldn't tell what was on the P5VD2-MX SE.
We need to make some sort of Database of FETs like that which we have with caps... Manufacturers know now that they can no longer get away with using inferior capacitors... Even Capxon branded polymers are still probably reliable. Sot hey skimp a few cents for off-brand grab bag junk transistors...
I read a little about FETs in Britannica, And from what I know they have to introduce some sort of impurity to affect the flow of electrons a certain way. I know it's vague, but with capacitors we pretty much know that it's either the inferior aluminium or the inferior electrolyte or both combined which defines its quality (Or lack thereof). Maybe the quality of the impurity is what is important here... Maybe it's the quality of the lithography (Do they use lithography for FETs - I'm not sure)...
If someone could start a section, explain the phenomenon of transistors taking out whole boards and also creating a databse of known good and off-brand transistors, it would be greatly appreciated... There's about a million different off-brand FETs I see even on 10 or more year old boards. It seems that today, with the more complex engineering of modern boards, their weakness shows more readily.
STMicroelectronics, Intersil (Sorry, this is the one with the "i" logo - I know it's a reliable brand but I don't know the name), NEC, etc - boards with these FETs always last forever when coupled with good caps.
Is anyone interested?
The customer called and said it wasn't working... Now he has it in a pretty tame environment... He uses it to check email. It has a 350-watt Fortron with all Teapo caps (None of which were bulged) and a very mediocre Pentium 4 6xx CPU. This system is never going to go anywhere near the maximum PSU output. I'd be surprised if it was drawing even 150 watts.
No problem I thought... Most likely there are some UCC KZGs in the VRM high as is usual with Asus. Replace them with those famous 8mm Nichicon HMs which I keep some stock of and away we go.
Imagine my surprise when I find out the motherboard has all solid caps, mostly from UCC, a few from Enesol or Apaq or whatever Asus uses.
Odd, I thought... When I cleaned everything in the garage, the PSU looked fine... Teapo usually does well when not stressed, and I have other customers with Teapo FSP PSUs which haven't complained... OK, let's change the PSU with a personally re-capped FSP. NADA!
After fidgeting with this system for a little while, I decided to try a brand new Seasonic S12-II series, which are famed for their reliability and all-Japanese capacitors. Maybe my refurbed PSU wasn't doing it (Eventhough I had tried 4 different PSUs I re-capped).
Same problem. Memory switched in from different system...
No beeps, nothing. Fans are spinning but no signal to screen.
At this point I try a re-capped Asus P5VD2-MX SE. SAME EXACT SYMPTOM!
Now I know that the problem with these boards are the shoddy transistors Asus uses. The P5K-VM used the infamous Taiwanese NIKOS brand FETs, and I couldn't tell what was on the P5VD2-MX SE.
We need to make some sort of Database of FETs like that which we have with caps... Manufacturers know now that they can no longer get away with using inferior capacitors... Even Capxon branded polymers are still probably reliable. Sot hey skimp a few cents for off-brand grab bag junk transistors...
I read a little about FETs in Britannica, And from what I know they have to introduce some sort of impurity to affect the flow of electrons a certain way. I know it's vague, but with capacitors we pretty much know that it's either the inferior aluminium or the inferior electrolyte or both combined which defines its quality (Or lack thereof). Maybe the quality of the impurity is what is important here... Maybe it's the quality of the lithography (Do they use lithography for FETs - I'm not sure)...
If someone could start a section, explain the phenomenon of transistors taking out whole boards and also creating a databse of known good and off-brand transistors, it would be greatly appreciated... There's about a million different off-brand FETs I see even on 10 or more year old boards. It seems that today, with the more complex engineering of modern boards, their weakness shows more readily.
STMicroelectronics, Intersil (Sorry, this is the one with the "i" logo - I know it's a reliable brand but I don't know the name), NEC, etc - boards with these FETs always last forever when coupled with good caps.
Is anyone interested?
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