OK, so I got some real data just now with my dummy load. Without the temperature control circuit, just shorting pin 4 to pin 8, the fan speeds up to about 7.4 volts max. I ran it for about 20 min this way until the internal temperature of the PSU stopped rising. The transformer inside the PSU got up to a whopping 245 degrees Fahrenheit! Then I did the same test but with my temperature controlled circuit installed so the fan was going at max, the same transformer only got up to 165 degrees Fahrenheit, a difference of 80 degrees, I think that is a significant improvement.

Originally Posted by Ohio AV8TOR

I have been using the DPS-600 for a year now with no problems. I am just using one for a 12v power supply. I converted it per the TJinTech article. I just now came across this thread. I did not try soldering the pins but rather used the servo leads and twisted and soldered. Is the any advantage to using the 6-8-10 jump over the 6-9-10? I have never done the 4-8 jump to quite the fan, is there any risk of overheating the ps by doing so? It sure would be nice to quite this down some


Regarding this image from above post, if I wanted to connect binding posts would the center two silver round head screws on standoffs be the location internally to connect to? (The red #1 arrow is kind of pointing to them)

6-8-10 is the correct combination for power-up. 6-9-10 works but it uses -S for ground which is why the output voltage is different.

Originally Posted by feathermerchant

Dusey - W/O the fan mod. There are many helicopter pilots at my field.
Noise of 1 helicopter = noise of 100 power supplies W/O fan mod.

Andrew - I can build you a unit that will output 36V (actually 37.5) or a unit that will do 50V.
See my blog. It would be an interesting experiment.

Hello feathermerchant

Thank you for the offer but it was a project i was planning on completing for the holidays coming up I also already have a 26-27.2v pair setup that i built so adding a third (which i already have, i actually have ten spare for in case) shouldn't be too difficult to implement. I just need to find a way to make it look neat.

Xandrios, thank you very much for that link. There are however a few issues that will arise: Firstly, the output voltage is 51.4 which will be above the rated voltage of the icharger, although im sure that the voltage can be turned down a fair amount to a level that is liked by the iCharger. Secondly, that ebay seller doesnt offer shipping to South Africa, although he might if i contact him. Thirdly, although it is really cheap, one DPS-600PB is cheaper to add and then i ahve the flexibility of running 13,26,39v when needed and i already have lots of them lying around

I'd just like to know if there are any issues i might have overlooked that arent present with a 24v setup?

I appreciate all the help i can get

Sounds good Andrew_ZA.

You should be good Andrew_ZA. You will need to isolate the DC ground on two of them (the 24v & 36v taps).

Sometime facts get in the way of our best laid plans...while developing a temperature controlled circuit for this PSU, I discovered something quite unexpected...check out this video!

Note, we made a temperature controlled circuit that will make the fan start at min speed at room temperature and then increase as the internal temperature rises until it is at full speed when the PSU is running at full capacity and ambient temperature is around 75 degrees. But I no longer think it is needed, watch the video and you will see what I mean. However, if you want one anyway (i.e. you are in a hot environment and just want to stay ahead of the temperature curve) PM me and I will make you one. So, the PSU obviously has built in thermal control, but at room temperature under full capacity, the fan will not go up to full speed. My circuit will drive it to full speed, so it will keep the PSU cooler...like I said, PM me if you want one, but I no longer think it is needed.

DPS-600PB pin4 fan mod = safe (4 min 15 sec)

Great post. Thank you for that. Seals the deal on the pin 4 mod.

Good job jocanon! Thanks for confirming the operation of the DPS-600PB's built-in thermal protection circuitry and providing such a convincing video. It's nice to have the peace of mind that we can do the pin 4 fan mod without worrying about a meltdown.

Thanks guys...I just want to add also that the thermal protection does not kick in until it is under load. So for instance, in my experiement, if I were to turn my dummy load down to 0 amps, the fan would speed down even with heat applied. It speeds up progressively as current is turned up AND as it heats up. I think the guys at HP really knew what they were doing when they designed this PSU.

Jo, my two supplies (24 volts, each) are set up using the ribbon method, and Aschu (sp?) kit modifications: can you provide a simple "how to" on (1) the location of pin 4 on the ribbon and (2) grounding it?

Hey, I know, but there is no harm in asking.

Sure, it is the third wire counting from the red one, i.e. the red wire is wire number 1. You simply include this wire with all the other wires when connecting them to ground. So how ever you are connecting the other wires to ground to turn on the PSU (there are various points at which to connect to ground), just connect wire 3 in the same exact place and you should be good to go.

I am going to run some more experiments when I get home tonight, but I may still want to mod the fan further than just connecting pin 4 to ground, not that I don't trust the guys at HP know what they are doing, but we are not necessarily using these PSUs as they were designed to be used. I am going to try to see if there is a way to incorporate the existing thermal protection but lower the temperature at which it reaches max speed just to keep things running cooler.

Originally Posted by jocanon

I am going to run some more experiments when I get home tonight, but I may still want to mod the fan further than just connecting pin 4 to ground, reason being, when I ran it at full capacity for about 10 to 15 min the case of the PSU got to about 120 degrees, almost to hot to touch. Now it's not that I don't trust the guys at HP know what they are doing, but we are not necessarily using these PSUs as they were designed to be used. I am going to try to see if there is a way to incorporate the existing thermal protection but lower the temperature at which it reaches max speed just to keep things running cooler.

Hmmm i wonder if the two pots on the one daughter board have anything to do with that...maybe given them a little play with

Thanks I will...I don't recall seeing those pots, where are they located, are they easy to find?

If you are looking at the binding posts, to the left of them is the largest daughter board. On that board there are two small pots that are silver about half way in the middle of the daughter board