This behavior is more like a broken
Posted: Mon Feb 17, 2025 4:12 am
The PWM tny264 and uln2003 were replaced, as well as the network and secondary capacitors. As a result, there is a surge in voltage from 0 to 6 instead of 12 volts and from 0 to 2 instead of 5 volts. I changed everything in the PWM strapping, the result is the same. Is it possible to short-circuit in the transformer? I found a diagram of the power supply, maybe you can advise something.
Judging by the diagram, I assume that you are tormenting the EVO-II board. I did not understand how it was possible to connect the heating element incorrectly, if it threw the phase to the case, then most likely there oman telegram data was a short circuit, and the result may well be that the microcircuit was broken. How does the control panel behave, what is blinking. Why did you change uln2003, was it clearly broken or are these just your assumptions. It is not advisable to check the transformer on the board, it is better to remove it and check.
A short circuit on the transformer is quite possible, but it behaves differently, there would hardly be pulses. diode, zener diode, capacitor or transistor, and also - the PWM is definitely working. Did you take measurements from the transformer? And if so, then you need to dig up the chain before it. In short, there can be a lot of reasons. From personal experience, in such cases, I first check the parts that I indicated in the photo, their values are under the photo, then unsolder uln2003 and check without it, then according to the circumstances. And write about the result
Zener diode = 4.35V, SMD capacitance 0.1 μF, but I don’t know the voltage, I take it from other boards, I don’t remember the transistor rating either - again, I take it from another module, somehow there was no need to look.
Judging by the diagram, I assume that you are tormenting the EVO-II board. I did not understand how it was possible to connect the heating element incorrectly, if it threw the phase to the case, then most likely there oman telegram data was a short circuit, and the result may well be that the microcircuit was broken. How does the control panel behave, what is blinking. Why did you change uln2003, was it clearly broken or are these just your assumptions. It is not advisable to check the transformer on the board, it is better to remove it and check.
A short circuit on the transformer is quite possible, but it behaves differently, there would hardly be pulses. diode, zener diode, capacitor or transistor, and also - the PWM is definitely working. Did you take measurements from the transformer? And if so, then you need to dig up the chain before it. In short, there can be a lot of reasons. From personal experience, in such cases, I first check the parts that I indicated in the photo, their values are under the photo, then unsolder uln2003 and check without it, then according to the circumstances. And write about the result
Zener diode = 4.35V, SMD capacitance 0.1 μF, but I don’t know the voltage, I take it from other boards, I don’t remember the transistor rating either - again, I take it from another module, somehow there was no need to look.