Author Topic: fixing a cheap inverter  (Read 2035 times)

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johnnym

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fixing a cheap inverter
« on: June 03, 2018, 12:55:54 PM »
Hello all, can someone tell me what parts of small dc-ac inverters go bad? This inverter I have was used to power a small chicken coop and got full of chicken crap... feathers, poop, etc... Embedded inside. It has been cleaned and it looks fine. All the components are still intact. I am just trying to pinpoint what part has gone bad. Saving electronic components is becoming a hobby of mine. You never know what you can salvage and use later. I would say I have used maybe 2% of all electronic components I have dissected but I find it very educational. Unlike when I was a kid and just took stuff apart for the hell of it, I am slowing learning to put them back together or successfully use the components on something else. 

Are certain parts more likely to fail before others in a dc-ac inverter? It is a 300 watt inverter with two outlets and usb. If I can't pinpoint the main problem then maybe I can just use the essential components. As in, what are the main/major components that make an inverter work. I hope this makes sense.

Mary B

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Re: fixing a cheap inverter
« Reply #1 on: June 03, 2018, 05:04:15 PM »
Start with the electrolytic capacitors... if any are swollen on top they are bad and it is a super common failure. But I would suspect corroded IC legs and board traces killed it. Chicken crap can eat metal.

OperaHouse

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Re: fixing a cheap inverter
« Reply #2 on: June 04, 2018, 01:59:44 PM »
What does it do now, blow fuse, alarm buzzer, won't turn on?

DanG

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Re: fixing a cheap inverter
« Reply #3 on: June 04, 2018, 07:08:26 PM »
Sounds more like an interconnect cable/plug/switch being held open by the merest excuse of chicken-sheet...

johnnym

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Re: fixing a cheap inverter
« Reply #4 on: June 04, 2018, 10:24:59 PM »
It simply wont turn on.

XeonPony

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Re: fixing a cheap inverter
« Reply #5 on: June 06, 2018, 01:46:31 PM »
Bird crap has high ammonia levels this will cause etching of copper that will not be easily seen, I'm afraid you have irreparably killed it by leaving it open to such contamination, let this be a lesson and protect the new one.

Care fully dismantle the old one and study it with a magnifying glass to see where all the corrosion is and how it degraded it.
Ignorance is not bliss, You may not know there is a semie behind you but you'll still be a hood ornimant!

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johnnym

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Re: fixing a cheap inverter
« Reply #6 on: June 10, 2018, 12:16:29 PM »
Cool, thanks for the tips every one. As I said, collecting components is becoming a hobby of mine. For example, I have used a ps4 lithium ion battery and usb and voltage controller from an old e-cig for a backup battery. Comes in handy sometimes. These are the types of things I like to do. I imagine if you have extensive knowledge in doing things like this (as a lot of you do) the possibilities of building something out of spare/scrap parts would be limited only to your imagination.

The essential parts of a dc-ac inverter are what exactly? I know you need a voltage regulator or controller, transformer, resistors, capacitors, transistor, maybe step up transformer depending on size?, etc... As a layman, it is difficult to know exactly what parts are needed. I tend to use my instinct more often than my brain which is not very efficient and potentially dangerous.

I think the problem is with the little plates on the sides but not positive. The capacitor is fine. I have no magnifying glass but behind the plates was a lot of poo and feather type crap. My idea is that is what killed it as you all have suggested.

Can someone tell me the main parts that make a dc-ac inverter operate?

Thank you everyone, this forum is always helpful.

Mary B

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Re: fixing a cheap inverter
« Reply #7 on: June 10, 2018, 06:27:22 PM »
Basic block diagram of a DC-AC inverter:

Input circuit/oscillator that takes your 12 volts and converts it to a pwm waveform

Driver circuit that takes the oscillator output and amplifies it to drive the FETs

FETS that drive the transformer

Transformer

Output filtering circuit(in some cheap inverters this is missing)

And a feedback circuit from out put to the PWM oscillator to keep the output voltage steady

tinyt

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Re: fixing a cheap inverter
« Reply #8 on: June 10, 2018, 08:52:23 PM »
Oztules did a lot of work in creating and testing an inverter design which is very popular (google ozinverter). He creates his PCBs without schematics. So I traced his PCBs and created the attached. Lately, there were issues with power on/off connection of J9 in the control PCB, pin 2 of J9 should never be left floating. Be adviced that the schematic is not updated to correct it.