Picture of High Voltage Power Supply from Laser Printer
Laser Printers are treasure troves of electronic goodies from gears to lasers to high voltage power supplies. High voltage is required in laser printing to create electrostatic charges to determine where the toner sticks, creating letters and images on paper. However, modern laser printers with their power saving designs and multiple safety features makes the power supply unusable unless connected to the cpu on the laser printer itself. Today, I will be showing you how you can trick the power supply into giving out juicy high voltage with just a bit of soldering.

SAFETY: Do not touch the circuit board when it is connected to mains voltage. Many heatsinks are live and will give you a dangerous and nasty shock from the mains. This is even deadlier than the high voltage produced by the power supply.

The printer i will be using is a SAMSUNG ML-1670. Its power supply outputs 4 different voltages.
1)Transfer High Voltage (THV+)
- Input Voltage : 24 V DC ± 15%
- Output Voltage : THV+: max +3.5kV ± 10 %,(Duty Variable, no loading ) @ 6.5uA
THV-: -1kV±20% (when cleaning,200 ㏁)
- Output Voltage Control Method : Transfer Output Voltage is outputted and controlled by changing Duty of
THVPWM Signal.

2) Charge Voltage (MHV)
- Input Voltage : 24 V DC ± 15%
- Output Voltage : -1.0KV ~ -1.8KV DC ± 3% @ 26uA
- Output Control Signal(MHV-PWM) : CPU is HV output when PWM is Low

3) Developing Voltage (DEV)
- Input Voltage : 24 V DC ± 15%
- Output Voltage: -200V ~ -500V DC ±3% @ 8.6uA
- Output Loading range : 10MΩ ~ 1000 MΩ
- Output Control Signal (BIAS-PWM) : the CPU output is HV output when PWM is low.

4) Supply
- Output Voltage : -350 V ~ -650V DC ±50 V(ZENER using, DEV ) @ 11.6uA
- Input contrast of the output stability degree : under ± 5 %
- Output Loading range : 10 MΩ ~ 1000 MΩ
- Output Control Signal (BIAS-PWM) : the CPU is HV output when PWM is low.
agulesin10 months ago

Hello there. Thanks for this interesting Inst. I love taking printers apart but never thought about getting the power supply to work "on it's own".

I'd just like to comment about your step 7 - 3rd item:

"3) Test the high voltage outputs with your fingers."

Even though you say its a joke, we have to be careful as anything we say might be taken literally by some people and YOU would be responsible. OK no-one is going to knock on your door or call the police, but imagine how bad you'd feel if you learnt someone was injured afterfollowing your instructions. Have a nice, safe day! ;-)