Hi guys,
I'm looking for some help in trouble shooting my solder station. It's a Duratool D00673 also sold as a Zhongdi ZD 916. The problem is that, when switched on the tip heats up but instead of stabilising at the set temp, it continues until it is glowing RED hot.
At first I thought it was probably the sensor, but I swapped that out for a new one, and this did not fix the issue. The LCD works and reports the tip temperature but for some reason the control system fails to work.
I opened up the box and inside are three circuit boards:-
The main board consists of some power supply circuitry, amplification circuitry (for the sensor ), an LCD driver and the micro-controller. There is a 2 wire connection from the handpiece, this gives a measurable and rising voltage as the tip heats up.
There is a two wire connection from the main board to the power supply board, this gives a steady voltage until the temperature reaches the set point, when it drops away to zero.
The power supply board contains a rectifier, a MOSFET and an opto-coupler for isolation.Whilst testing the two wire connection from the main board, I noticed that the Mosfet was providing power to the handpiece regardless of whether the control wires from the main board were connected or not. I think the problem lies here.
Perhaps someone could explain how the power supply circuit works, or point me in the right direction towards resolving this situation.
I have included some photographs, data-sheets and a schematic that I traced from the power supply circuit (this my first time at reverse engineering, so please forgive any errors).
TIA Steve.
I'm looking for some help in trouble shooting my solder station. It's a Duratool D00673 also sold as a Zhongdi ZD 916. The problem is that, when switched on the tip heats up but instead of stabilising at the set temp, it continues until it is glowing RED hot.
At first I thought it was probably the sensor, but I swapped that out for a new one, and this did not fix the issue. The LCD works and reports the tip temperature but for some reason the control system fails to work.
I opened up the box and inside are three circuit boards:-
- Power supply board
- Main board
- Push button board
The main board consists of some power supply circuitry, amplification circuitry (for the sensor ), an LCD driver and the micro-controller. There is a 2 wire connection from the handpiece, this gives a measurable and rising voltage as the tip heats up.
There is a two wire connection from the main board to the power supply board, this gives a steady voltage until the temperature reaches the set point, when it drops away to zero.
The power supply board contains a rectifier, a MOSFET and an opto-coupler for isolation.Whilst testing the two wire connection from the main board, I noticed that the Mosfet was providing power to the handpiece regardless of whether the control wires from the main board were connected or not. I think the problem lies here.
Perhaps someone could explain how the power supply circuit works, or point me in the right direction towards resolving this situation.
I have included some photographs, data-sheets and a schematic that I traced from the power supply circuit (this my first time at reverse engineering, so please forgive any errors).
TIA Steve.
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