Chingy's F5 biased this weekend.
Detail of AC/transformer connections to the PSU PCB
I prefer Mica & silicone goo. Keratherm is bit ... $$$$ and nothing else will transfer the heat fast enough.
Screws and washers. Tighten nicely, but do not go crazy! When you see the goo stops escaping under the FET to the outside, that's the sign it's tight enough.
Mind the PCB/FETs clearance to the heatsink!
Always short the input first!
Warming up the 1st channel. Took close to an hour for the heatsink to start feeling just barely warm. The heatsink is about 4 times the necessary size, that's why... :whistler: You use waht's handy...
1st channel set to final bias (I'll explain...)
2nd channel warm up...
and finished
Bias explanation:
I set the final bias after the FETs are under the working temperature based on 225VAC. The reason why 550mV instead of 590-600mV as per manual is because of wild .za AC fluctuations. My own supply varies by nearly 10V on any given day, and if Chingy is on the direct pipeline from Koeberg... brrrr. Better safe than sorry. 550mV makes it perfectly safe for up to 240VAC.
Chingy? Happiness?
:dop:
Detail of AC/transformer connections to the PSU PCB
I prefer Mica & silicone goo. Keratherm is bit ... $$$$ and nothing else will transfer the heat fast enough.
Screws and washers. Tighten nicely, but do not go crazy! When you see the goo stops escaping under the FET to the outside, that's the sign it's tight enough.
Mind the PCB/FETs clearance to the heatsink!
Always short the input first!
Warming up the 1st channel. Took close to an hour for the heatsink to start feeling just barely warm. The heatsink is about 4 times the necessary size, that's why... :whistler: You use waht's handy...
1st channel set to final bias (I'll explain...)
2nd channel warm up...
and finished
Bias explanation:
I set the final bias after the FETs are under the working temperature based on 225VAC. The reason why 550mV instead of 590-600mV as per manual is because of wild .za AC fluctuations. My own supply varies by nearly 10V on any given day, and if Chingy is on the direct pipeline from Koeberg... brrrr. Better safe than sorry. 550mV makes it perfectly safe for up to 240VAC.
Chingy? Happiness?
:dop:
