Log book

I was previously never been a fan of switch mode power supplies due to their reputation for RF noise, but I came across a project using one salvaged from a HP server claiming to be very quite RF wise.

At £7.79 from eBay I thought they were worth a punt and ordered one. I ended up converting a number of them and they are my stock PSU often built into speaker cabinets.

The specification for these are very impressive

i) Designed to run at 12V at 63A at 100% duty cycle for 7 years without interruption.

ii) Unmodified can run at 12.5V

iii) Modified can run at 13.8V at 50A (choose model carefully they are not all easy to modify and do differ by model).

iv) Fitted with over voltage, over current and over temperature protection.

v) High quality construction.

Getting it up and running

There are two common versions of the power supply and the conversion method is different.

HSTNS-PD18 version

The PD18 version requires a link between pin 33 and the negative power pad and a 22K resistor between pins 36 and 37 to power

up. If you want a simple on/off switch route the kink beteen pin 33 and earth via a off/on swith to put the PSU into standby.

Start wiring

HSTNS-PL18 version

This is even easier and just requires a link between pin 33 and 36 (the short one). I used the small header terminal rather than the

terminal pads to make it look tidier.

13.5V modification (PD18 Version).

i) Install a 1/4W 22K resistor from earth connection 4th pin from left on bottom connection to LHS tab of the 3rd variable resistor.

ii) I adjusted the voltage to 13.5V rather than 13.8V as it sometimes tripped on over voltage on start up.

Voltage adjust

13.5V modification (PL18 Version).

I) Remove and bridge 100 ohm resistor.

II) Adjust variable resistor to give 13.5V rather than 13.8V as it sometimes tripped on over voltage on start up.

HSTNC-PL18

Power supply build into Yaesu SP101 speaker cabinet.

SP101 Speaker PSU

Further info

Start mod for PD-18 Version:-

https://makenotes.de/2020/04/turning-on-a-hp-dps-750rb-server-power-supply/

Voltage mod video for PD-18 version:-

https://www.youtube.com/watch?v=tqDNg_HCvFk

Convertion info for PL-18 version:-

A power supply at a low price – ON5VL Use google translate to convert it from French.

Disclaimer

Information is beleaved to be correct but you modify at your own risk as I cannot accept responsiblity for errors and/or omissions. Some
parts of the poer supply are at mains voltage so keep fingers clear.