3 Questions, will my k40 mini power supply, power a

according to Thermal design tips for cooling your electronics - Embedded.com thermal pads are crap, the mosfet nder the power supply had 2, I am gonna lightly lap them then re-seat them with some thermal grease some good stuff, newegg stated changing your thermal grease is a yearly task, You guys always complain the power supplies are garbage, are you lapping your mosfets? Are you re-seating your mosfets or upgrading the heat sinks? This old news?

My power supply, I took it apart, unscrewed it saw the mosfets? they had 15% surface covered in thermal compound and squeese out where was not helpful, I spread the squeeze out to all surfaces evenly on them left and only in 1 spot, ordered some good thermal paste an am planning an upgrade.

1.) Will my k40 mini power supply, power a 720mm full size tube?

2.) Will my k40 mini power supply power a 50w tube?

3.) If I install a 100w tube and install the k40 mini power supply to it, What will happen?

4.) Can I install a 50w flyback transformer in this and power the 50w? or a 60? It seems like they are the same? Whats going on here?

5.) I have the bridge rectifiers in my shopping cart $2 for but id rather not, does anyone have an extra RS507, 700V, 5A bridge rectifier? Is my power supply an already upgraded model?

Not sure what you mean by an upgraded model? In the multiples of supplies, I have helped troubleshoot only a few had a bridge, diode, or MOSFET failure. Usually, the HVT goes bad before anything else. We mostly recommend just replacing the supply at failure as its usually not cost-effective, not to mention dangerous, to repair them

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Since my first post I have dug in really deep, learning some component level diagnosis and repair looking up how to power the capacitors and laser in my board before thinking about taking the apart. I am taking the necessary steps to discharge charged components and carefully asses the risk of any repair I undertake.

I needed to take the power supply apart to screw the fan to the power supply thinking I was gonna use nuts and bolts. Then noticed there were 2 mosfets screwed to the side of the power supply simply pressed against the side of the power supply housing with no thermal grease and 2 under the board. With thermal pads and grease. I figured, since I disturbed the connection and was worth while to move the pads and put new grease.

Heat sink paste dries out. Not in 1 year not in 2 or 3 but 4-6 and even longer there is always room for more thermal tranfer. Also, when you are in the mood to take a 17 dollar power supply apart and soup it up, you`re in the mood. I think I will chech my rectifier to see if it is the 1a unit if so, I will do the swap as preventative maintence when I am adding artic silver 5 to the mosfets. All of them including those in the wall.

1 more question, if I screw the fan to the power supply, should it be sucking air rhrough the power supply or pushing air through the power supply?

https://hawklaser.com/k40-parts/k40-spare-upgrade-parts/electronics/psu-repair-kit/ "Has your PSU gone boom-boom?
The most common problems with the PSU´s are a blown fuse, due to a burned bridge rectifier.

Since mid 2018 the manufacturer started to install better components in the power supplies. Check the writing on your rectifier, google the number/id and see if it has more than 4A and 600V – if it does, you do not need this repair kit!" that’s where I read that,

Another question, If I buy a 60w laser power supply will I be able to power my 25w 630mm tube and a 50w 830mm tube? Or does it need to be powering 60w tube or higher?

Note that the thermal pads under the power mosfets also isolate the mosfet electrically! If you replace them with just thermal paste, the mosfets will shorten with a loud bang… how do i know? I repaired mine 20 times. One of those times, the mosfet was blown due to a shortened HV coil. So i replaced the mosfet with the thermal pads but accident a small metal burr got under it and punched thru one of the thermal pads. The explosion was impressive but the rework wasn’t :slight_smile: Disassemble and assemble the whole thing again is a pain in the bum. Good luck.


Good thing I did not remove them and use only paste like I was planning! I guess I will clean the pads, clean the chip, and use the thermal grease.

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Upgraded my 35w one with no issues