Nordac SK500E-301-340-A-ERS Not turning on repair

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Nordac SK500E-301-340-A-ERS Not turning on repair
Device
Affects part(s)
Needs equipment
Difficulty
Type

Problem description

Repairing a problem with this Nordac inverter where the upon connecting it to power, the inverter doesn't turn on or react to it. This issue is cased by a fault in the DC-DC (figure 1) circuit.

DC-DC circuit on the inverter in the smaller board. (Figure 1)

The vertical PCB (Figure 2)

DC-DC transformer (Figure 3)

Symptoms

• Not turning on
• Not reacting to power

Solution

Diagnostic Steps

• Disassemble the device, make sure there is no physical damage.
• On the vertical PCB (figure 2), make sure there is no short circuits on any of the capacitors, if there is any, you need to find where with voltage injection.
• If there are no shorts, measure the power MOSFET, make sure it's working properly.
• If everything is good, confirm the pwm controller is working fine. Find it's datasheet and measure VCC etc.
• If all is good, measure the transformer's windings (Figure 3), the pins that are further from the rest are the primary. In this case it was Open Line which means it is faulty and needs replacement.

Repair Steps

Replace any faulty components you find. The PWM controller, MOSFET, or transformer. If you look up the transformer's name on eBay, you can find replacement but it's rather expensive. Unfortunately there is no way to regenerate this transformer since it's filled with resin. There's no way to know the number of windings to make a new one either, so the only way is to buy a new one.