Hello,
The PSU was totally dead, the following parts were burnt O/C or SHORTED in the primary section:
R14 -> R17 - Burnt O/C - 2.4 ohms,
R18 -> Burnt O/C - 910 ohms,
Q1 -> P7NK80ZFP - SHORTED,
U1 -> PWM Controller UC3843B - SHORTED.
I have ordered all the parts but there is also a Zener SHORTED and need help to know what to repace it with as no markings and the schematics are not available as far as I could find online.
It is ZD1. I have attached pictures showing the location and drawn out the part of the circuit it is on...
I would like to know it's function please as well as the other resistors and zener in the same path from the OUTPUT pin of the PWM to the MOSFET Q1.
I have attached the datasheets for the PWM and MOSFET. The PWM datasheet states it can be connected directly to the MOSFET Gate yet it is not so an explanation of their functions would be great please.
Also can the blown ZENER be omitted? Is it critical to functionality or some sort of protection for the PWM or MOSFET? My experience of zeners is only when used as a voltage regulator so I am not sure of their functions in this case.
The pictures are off the internet as they are clearer than mine came out.
Many thanks.
The PSU was totally dead, the following parts were burnt O/C or SHORTED in the primary section:
R14 -> R17 - Burnt O/C - 2.4 ohms,
R18 -> Burnt O/C - 910 ohms,
Q1 -> P7NK80ZFP - SHORTED,
U1 -> PWM Controller UC3843B - SHORTED.
I have ordered all the parts but there is also a Zener SHORTED and need help to know what to repace it with as no markings and the schematics are not available as far as I could find online.
It is ZD1. I have attached pictures showing the location and drawn out the part of the circuit it is on...
I would like to know it's function please as well as the other resistors and zener in the same path from the OUTPUT pin of the PWM to the MOSFET Q1.
I have attached the datasheets for the PWM and MOSFET. The PWM datasheet states it can be connected directly to the MOSFET Gate yet it is not so an explanation of their functions would be great please.
Also can the blown ZENER be omitted? Is it critical to functionality or some sort of protection for the PWM or MOSFET? My experience of zeners is only when used as a voltage regulator so I am not sure of their functions in this case.
The pictures are off the internet as they are clearer than mine came out.
Many thanks.
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