Update: Two Monarch have come in for servicing under the feed a homeless person program. And it looks like people will be fed this T-day. Good.
The first one was a 500gh Monarch that had the coolant leak out of it and was shorting out power supplies. Blown FETs as discussed. I've tried to put on new little metal ones, but I am running into three problems:
1) These boards are *heavy*. As in so much copper that they literally dissipate heat from my air tools faster than I can put it down. Even with a full 380F of pre-heat with a 15 minute preheat time *and* pulling off the back heat sink *and* using Kesterel liquid flux *AND* running my heat want at 425C I can barely get the metal FETs off.
2) I haven't figured out quite how to put them back on; the problem is the gate and source pins are *under* the FET and heating through those FETs with this much heat isn't the best of ideas. I might need a bigger preheater.
3) Did I mention these boards are heavy?
So I did what I usually do: I tried something else. BFL left on the old T-MAX pins for the bigger more traditional FETs, so I went to the Digi-Key cupboard and gave some a try.
I used two types of high frequency FETs on the Jalapenos: 052NE3LS types and CSD17506 types. The 17507s that were typically used had high gate capacitance, and running them in parallel was kind of a bad idea. 17506's and 052's have much lower capacitance, with the 052's trading some gate values for more power handling.
Bad idea here: Those Intersil drivers are running the FETs at way higher frequencies for power balancig. Gate float, blew the 052's. Boom.
Next up: 17506's. Put them on and even though they have lower on current max values they spend most of their time in transition switching and can get in and out of the death zone much faster. They don't even get *WARM* for Christ's sake.
So running 6 of them on the right side chip is giving me 275gh at 28c. Very cool, very smooth, running well. The left side is still shorted from the water damage, need to work on that a bit more to see what's up.
Now you may be thinking "How is he cooling the chip with a broken water block". Well...
BWAHAHAHAHAHA!!!!!!!!!
Yep. That's an old Single/50 heat sink on a Monarch with a Single fan on a stand-off. I actually used the little plate on the back as a gauge, went into the shed, and used the drill press to drill four holes around the edge, then tapped them with the 3mm tap. Then mounted it to the chip with AS5 heat sink compound and screwed it in the back with screws using the little springs to maintain tension without cracking the chip. The other side doesn't need a sink because the power FETs are not working (and three are removed).
Yep. It works. The back of the board behind the chip is reading a bit warm at 50c, but the heat sink is also reading 50c which means it's transferring heat optimally. And oddly enough it works, I haven't run it for more than 30 minutes but it is quite thermally stable.
I'm going to give Cool-IT another few days to respond, then try fixing the leak by potting the water block inside the housing. That should do it since the pressures are low, but it's water, so who knows.
More later. Moral: They can be fixed. Now you know how.