2000 watt harbour freight inverter

Thread Starter

twister007

Joined Feb 29, 2012
58
I think I damaged the on and off circuit on this inverter. I may have accidentally grounded the power switch or applied 12 volts to it.
This is the IC that the power switch applies 5V to, to turn on the inverter.
EM78P176M5018J What does this chip do and how to test it?
There is another IC, KA3525A SMPS.
If I applied 12V to pin 15 and pin 13, of the SMPS, would that let the inverter start?
In the pictures, the 2 pads on the end, of the multiple pin IC is where the 5V is applied which 0514221754.jpg0514221749.jpgdrops to 2.4V when on. But the inverter doesn't turn on.
I could not find any model number anywhere.
 

Thread Starter

twister007

Joined Feb 29, 2012
58
How did you manage to do that?

Those chips are complex devices and would require specialized test setups to determine if they work.
I run everything on solar power. The problem with inverters is that when the battery voltage gets low, they shut off. When a refrigerator is running they will shut off but when the inverter shuts off, the battery voltage recovers and the inverter turns on again and the refrigerator tries to start again. Over and over again till the refrigerator is ruined. I designed a circuit to monitor the voltage and the sunlit that would control the inverter. It worked great for a year but somehow some wires came unhooked and I may have shorted out the control wire. My theory is, that the control chip is bad, but I can't get any data for that chip or where I can get another one. I'm able to understand complex circuits. Cann you help? Or not?
 

Thread Starter

twister007

Joined Feb 29, 2012
58
EM78P176 is a microcontroller. You don’t know what it is programmed to do, but it’s a pretty safe bet that is is OK if there is a signal on the clock out pins.
https://www.electronicsdatasheets.com/download/534cf558e34e2406135f4443.pdf?format=pdf
KA3525 is a cheap-as-chips switched-mode IC, also known as SG3525
https://www.onsemi.com/pdf/datasheet/sg3525a-d.pdf
Thanks a million for the help. Mabe I can figure out how to just bypass the chip and get the inverter to turn on and off. My circuit works far better than that chip did anyway!
 

Thread Starter

twister007

Joined Feb 29, 2012
58
Well, there is no oscilator signal that I can detect with an oscilloscope, so I guess this IC is dead. I will have to buy a new inverter. Thanks for the help.
 
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