So after faulty cheap Chinese module number 17 takes a trip to the woods, I have some little MP1584EN-based switchers on the way, but they'll take a week or six because China.
Engage
"getting the fuck on with my life" mode. All I REALLY care about at this point is powering the 12V/0.12A 80mm Arctic silent case fan I just got in; it replaces one of the screamin' mimi 40mm fans on the unit, the one that cools the mainboard. While I AM pretty certain there's a setting where I could dial down the PWM for that fan channel in the firmware, I'm already annoyed and decide to apply the KISS principle. 500mA L78M12, a 47uF/16V MMLCC cap strapped across the output for stability and a bit of 0.100" pin header.
"But wait..." you cry out
"There's no heat-sink, and that's still ~1.5W or so dropped across the poor thing." But there is: 200mm of 18ga copper soldered right to the heat-sink tab. Thermal Design Considerations, yeahahh. And another similar mass of copper on the Vout. Yes, it MATTERS. Testing
in situ reveals it gets just warm to the touch; maybe 45-50°C after 20 minutes. I sleeve it with some heat-shrink and plop the fan in place; put the bottom cover on the printer and set it upright. All told I've spent maybe an hour; that includes making a baffle and a filler panel for where the 40mm fan used to be. I really didn't expect it to make much difference yet; the hotend still has another 40x10mm & 30x10mm screamers on it. But it IS noticeable.
Of course, while I'm in there I find THIS:
Reviewing my original pics of the inside, I see that the heatsink is in fact loose there too. Whether I hamfisted it loose while I was in there poking around, or it was never attached correctly I don't know.
But this heatsink is just held on with cheap frag tape; unlike the ones on the TM2208s which are attached with silicone thermal cement.
So... I go shopping for some better heatsinks and maybe a tube of similar thermal cement, and I stumble across one of these MOSFET modules; following that rabbit-hole I find that while I can buy one for $11 and wait a month, I can get 4 of them PLUS wiring kit for $16 delivered TOMORROW.
https://www.amazon.ca/gp/product/B077PPWZLB/I'll let 'yall know how things look when it arrives; right now I'm trying to talk myself out of rebuilding the hotend with my kit of V6 parts, since I just found out the silicone socks I got with are NOT "close enough" to go on the Mk8 hotend.
Someday I'll actually get around to printing the Petsfang and these much quieter 5015 & 4020 fans installed. mnem
*hammering noises... chisel-chisel...!! braaap-braaaapppp...!! griiiiiiiiiiiind....!!!*