Transformer help

[DesireGood]

This may not even be doable, but I am willing to try.

My son and I miscommunicated, and I accidentally left his electronic generator in the weather. And, yes, it rained. And, yes, it got really wet inside. I read a lot about moisture sensitive component levels. I have no idea what MS levels these parts are. The manual said not to get it wet or things like happened to me could happen. I am hoping that that was more because of the quality of parts rather than it being an extensive problem.

My son said that there was what he thought to be a bad design with the unit, in that, it would drain of power on it's own, which is what I think led to its downfall in being problematic to moisture while also conducting electricity. My hope is that this is a transformer issue or perhaps some other easier to solve components - like typical components to fail with moisture exposure. Could it be that the transformer's coil wires overheated and are creating the dead short?

The batteries still have voltage, but when trying to plug the power source (batteries) into the circuit board in the pictures, there is a dead short. I tested it with an ohmmeter, and I got the same result - a closed circuit.

Where should I begin on this project? Even if it is a dim hope? Also, I contacted the manufacturer, and I was told to buy the most current unit and that they didn't have any way of fixing nor refurbishing the unit. I wanted to simply buy the board, but they said it wasn't available.

Thanks!

 

[NOON Design]

Do you mean this is an inverter, used to convert battery DC voltages to mains AC voltages? It should be like any other circuit board, if it's alliwed to dry very thoroughly before power is applied it will probably be ok. If you applied power while there  was still moisture in some components then there could be all sorts of things wrong now.
Try giving it a good wash and scrub with some pure isopropyl alcohol and then let it dry for a few days or put it in a very low oven for a few hours.
Then try measuring impedances and checking components for damage.

[DesireGood]

Thank you for your reply!

Yes. It is a bunch of things. (see pics)

Well, it was hooked up while rain was coming down on it. After we got it apart, we disassembled it.

I'll try the alcohol. I am really a noob on this. Do I just buy some like 93% and pour it over it, and then set it out in the sun? I think our oven goes only down to 200 or somewhere there abouts.

[Alti]

"Moisture sensitivity" and "pouring rain" are different things.
You could search for term "liquid damage" and look for someone who could deal with this.
If you applied power to a flooded electronics - I doubt there is economical way to bring it back to reliability. It is not necessary to start it to destroy it, just connecting battery leads to irreversible damage.

[DesireGood]

I think I already covered what we did and how it is made. But just in case ...

It was already connected. When we took it apart, we disconnected it. It's the way it is made. It isn't made to be taken apart by the consumer. We took it apart to inspect it.

[jonpaul]

hello, exposure to moisture, water, contamination when operation causes electrolysis of the copper and other metal, eg transistors ,diodes, PCB traces.

The green solder mask is not  protection

Usually the board,and parts need a very through inspection for corrosion and bridging, then cleaning with 99% isopropyl alcohol, and possibly stronger cleaners.

Small wire brushes, toothbrushes....

Expect it may be dead or blow up upon full power, use caution.

If a cheap Chinese device, just get a,new one.

Jon

[DesireGood]

Thank you, Jon. I'll do that and hope for the best. 

[jonpaul]

the destruction by electrolysis is the amount of metal etched or redeposited.

is dependent on integral of current over time. ( Faraday's law)
and purity or contamination of the water.

Every conductor pair Spacing , insulation, voltage will be an issue.

In some Tektronix scopes with leaky  SMD capacitors, many components are destroyed or changed and PCB traces opened up or bridged.

4 layer boards have internally damage, very hard to find all the damages.

As the max power and voltage on the board increased the issues are worse.

For,really bad damage, flush with distilled water, use baking soda if acid damage.
Scrub.
Then isopropyl alcohol
Finally we use heat gun or oven on very low heat, to throughly dry

Then carefully test the board.

Jon

[DesireGood]

So when I clean it, and, if after I test it, if it still has issues, and if I just want to have the satisfaction of finding the faulty part, which would be the most likely component or components to remove and test?

[jonpaul]

Rebonjour Cher Monsieur

The water and electrolysis damage may be seen with strong light and magnifier, but any component or PCB trace,may have invisible damage.

There isn't no most likely suspect, it,can be anywhere and in many places.

Even if it,runs a,bit, I would not depend on continuing reliable use.

Jon

[DesireGood]

Ah! That paints a clearer picture for me (noob here)!

I bought some alcohol. A guy I know who was a Navy Petty Officer (I gave him a ride today), he recommended putting the component in rice to help draw out the moisture too.

[srb1954]

Thank you for your reply!

Yes. It is a bunch of things. (see pics)

Well, it was hooked up while rain was coming down on it. After we got it apart, we disassembled it.

I'll try the alcohol. I am really a noob on this. Do I just buy some like 93% and pour it over it, and then set it out in the sun? I think our oven goes only down to 200 or somewhere there abouts.

200℉ is a little too hot to be entirely safe with all electronics. I would recommend no more than 160℉ (71℃).

[srb1954]

Ah! That pains a clearer picture for me (noob here)!

I bought some alcohol. A guy I know who was a Navy Petty Officer (I gave him a ride today), he recommended putting the component in rice to help draw out the moisture too.

Rice won't help much and it will be extremely slow to draw out the moisture.

Repeated applications of the 93% iso-propyl alcohol followed by plenty of warm (not hot) air from a heat gun or hair dryer will be more effective and much faster at extracting any residual moisture.

[DesireGood]

Cool! So how much alcohol? Do I dip it, leave it in a bath, spray it on with a mist, pour it on by just taking the cap off and chugging it over the board? 

[jonpaul]

Cher Desire,

,

use syringe or small tube/ baister, carefully load a few cc at a time 91..99% isopropyl alcohol

hold board vertica, inject alcohol over upper surface start top to bottom

Use toothbrushes or Q tips, to Scrub affected,areas.

Repeat on board bottom

Repeat procees and cleaning till all traces,of dirt, corrosion etc are gone.

Let dry in the sun or use hair drier, heat gun to gently warm from distance 75..150 mm

Do not use oven.

test after throughly clean and dry

Bon chance

Jon

[DesireGood]

Got it! Thank you! I will probably try at it tomorrow.

[jonpaul]

Rebonjour Cher Monsieur

Re-reading this,tale, saw,the photos,, PCB and "dead short" just now.

If unit was,energized during rain, likely  power transistors were,destroyed by disrupted,drive.

That will explain the dead,short.

QThe unit is just consumer junk with a poorly designed cheap PCB, worth perhaps $10 in BOM parts.

Suspect that you paid,$150 retail for the device.

As a power electronics engineer since 1970s, I am sad to say cleaning the board,will not revive and troubleshooting requires special lab .equipment and experience.


try anyway but perhaps a lost cause....
very sorry....live and learn,

Jon

Jon

[Eraldo]

Dead shorts in invertors in my experience would mean only one thing, a power mosfet has failed in the circuit. I would start  desoldering the mosfets and check them if they are still shorted.

I found a UPS one time in the dumpster which had this problem (but it was not caused from the rain though) and in my case there were 2 pairs of mosfet (2 per line in parallel) so just removin one of the defective one fixed it. But of course i won't use it until i find a replacement for that component and buy some new fuses which were burnt.

But even after replacing those mosfets there will definetly be more problems inside so you definetly need to dry it and clean it well like ppl said above. And don't connect any batteries until the short is resolved. Another thing there should be also some fuses blown in the battery side so definetly replace them with same rated ones.

Good luck

[DesireGood]

Thanks for the help, y'all! I will be tackling this project with your advice and thoughts in mind. 

[DesireGood]

I came across two links. Both seemed plausible though the first one, especially, the second reply, seemed easier for me to imagine that I myself could do because it seemed to make more sense though the first reply helped a lot as well. The second link was quite technical, but, with time and tools, I can imagine myself trying its options as well.

Can y'all give me a heads up on which way(s) to go?

https://electronics.stackexchange.com/questions/414698/how-can-you-conduct-a-simple-test-for-a-mosfet

https://www.wellpcb.com/testing-a-mosfet.html

[Eraldo]

Start by desoldering one of the mosfet at random (mosfet roulette)  and check if the short is still there after removing it, remove the other one too. Check the mosfets if they have a short and then the board too just in case. I assume the 2 mosfets are the ones closest to the battery cables (the 2 smaller chips in the heatsink) but just in case check out the datasheet of those components in alldatasheet.com.

That's it. Good luck

[DesireGood]

Thank you!

My son said that the ends where the fans go is where most of the water was. I noticed too that there is like a protection type of caulk around certain components. I wonder if they are more susceptible to problems. So I will start as you wrote for me to do.