The most important thing with electronics is sufficient cooling. You don´t need to follow this article and flip your PSU, but look into adding one or more fans to take out the hot air from the smaller compartment.

Electronics are sensitive for heat and high temperatures. The higher temps the less efficiency you get out of the PSU.
And now we are talking about Chinese middle class quality the temperatures are more important than ever.

Here is my solution to this problem. Tilt the PSU 90 degrees, so the fan in the PSU grabs air from the ambient temp in your room, instead of breathing the heated air inside the machine.
Check orientation of your fan – you want it to pull air from the outside towards the circuitboard, flip it if its the wrong way.

My example using a 3D-printed bracket to bolt the PSU tilted.
You can also use double sided tape if you do not own a 3D printer, just make sure you add a extra ground wire from the chassis to one of the bolts on the casing of the PSU.
Here is the link to the 3D-printed bracket on Thingiverse

I have done some extensive testing about this.
I just added some lines and let the machine run for 10 minutes, between every test the machine was resting and i was waiting for the water temp to reset to 19c.

I was checking the power output and the temperatures inside the PSU.
I have the digital version of the K40, i was using the same %-value in power every test, never touched the settings.

Test with the PSU inside the machine
Test 1: 64c – 14.4mA
Test 2: 65c – 13.7mA
Test 3: 64c – 14.2mA
Test 4: 64c – 14.4mA
Test 5: 65c – 14.0mA

Test with the PSU breathing ambient temps
Test 1: 34c – 16.2mA
Test 2: 34c – 16.4mA
Test 3: 33c – 16.8mA
Test 4: 33c – 16.6mA
Test 5: 34c – 16.2mA

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Jim Rohrer

Excellent site! Thank you for sharing you expertise. Back in my tv repair days we would identify a high voltage leak by a distinctive high pitch squeak. I notice similar sound in area of psu after a half minute of use and a 15% drop in current seems to support the leak theory but no visible arc or ozone. Any guidance on possible cause, locating and addressing? In the meantime, I plan to tilt my psu and reverse the fan to optimize breathing. hopefully cooling will help. Currently have a bench meter measuring current. Otherwise machine is still the digital version with no meter.

Jim Rohrer

You were right. The HV leak is inside the tube. I can see it arc sideways. Was using RO water but had not changed in a while. Cleaned and flushed and seeing much improvement. I’m now working through your cooling info. Thanks so much! PSU is tilted and permanent ammeter installed. 5 bad crimps found so thanks for that heads up.

Bill Lynch

Machine stopped working while setting up, was hesitating while jogging to position. Everything is dead no lights , ventilation , or digital read outs. Looked at fuse ,appears to be good, no visible burns on board . Machine has a jg-40w power supply ,rectifier bridge is a GBU 610. What should I look at next?


Thanks for the detailed website! There is a lot of valuable information here. I have a question about tilting the power supply 90Deg.

You said “Tilt the PSU 90 degrees, so the fan in the PSU grabs air from the ambient temp in your room, instead of breathing the heated air inside the machine.”

I have slots on the side of the machine where ambient temp air could be pulled into the housing that contains the PSU, but the fan on my power supply blows out away from the PSU not blowing INTO the PSU. Is this still correct? Because It would still grab warm air from inside the compartment and exhaust it out the slots on the side of my machine.

Or should I flip the fan around so it would draw air in from the slots, and blow it across the PCB of the Power Supply?