Completely destroyed this fan driver

Airwalker16

Airwalker16

Well-Known Member
Hey guys I wanted to add a few fans to my veg area today so I had these small drivers that ran the fans inside my old EcoSun Chinese light. So I popped the covers off of them to see why so many wires were coming out and like I expected the input just had multiple wires all going to the same Trace. So I removed all but one pair to make it less jumbled(see pics). But anyways on an American plug there's a wider prong that I thought was line but maybe I'm wrong. Anyways I wired the input up positive to The Wider prong on the cord and wanted to plug it in to test with a multimeter the outputs and just see what the different wires were showing. But when I did, a big POP!!! and my entire room went dark and quiet.
I tripped my breaker. Thank God they work so well cause it scared the shit out of me. Can anyone explain to me what exactly happened? And what are all these different outputs for because they don't all go to the same Trace? The 2 separate pod and neg outputs are on the very left of the PCB. Pos and neg on the top 2 close through holes and the other pos and neg are on the lower 2.
IMAG0426.jpg IMAG0424.jpg IMAG0421.jpg IMAG0414.jpg IMAG0415.jpg IMAG0420.jpg IMAG0417.jpg
 
JavaCo

JavaCo

Well-Known Member
Shorted to ground or neutral , AC looks to be in the right spot. All it can be really testing with a ohm meter before plugging it in would have shown the short.
 
JavaCo

JavaCo

Well-Known Member
Renfro said:
Sure looks like the board got toasted, are you sure the AC wasn't put on the DC output?
Click to expand...
The front view shows the AC input on the bottom right hand corner flip the PCB over and it goes to the top right hand corner. So he didn't switch them around just have to account for the board being flipped over.
 
Renfro

Renfro

Well-Known Member
Can't really tell whats hooked to what but unless the output was shorted out somehow I don't see how that got so burnt, heck even if it was shorted that looks like AC was on the DC side.
 
Renfro

Renfro

Well-Known Member
The wider prong on an american AC cord is neutral. Switching the neutral and Line wouldn't cause this though.

I really think AC was applied to the DC side.
 
Airwalker16

Airwalker16

Well-Known Member
These pics are of TWO separate boards. I should have mentioned that. My bad. I have two drivers and opened them both.
No, I definitely put the wires right. It popped loudly. At the board and the outlet.
The wires all exit the case on the right side. Input wires are bottom right hole and the output wires stretch back across the board and go out the TOP right out a larger hole.
WTF happened? All the surface mounts exploded. I saw small explosions as the room went dark too. Small little quick glow of orange.
 
Airwalker16

Airwalker16

Well-Known Member
Also, you can see in the pic the output wires have connectors on the ends of them. So those touching together to short isn't possible.
 
Airwalker16

Airwalker16

Well-Known Member
The Larger prong on plugs is not the Hot/Line/+ wire? It's the Neutral/- wire?
I wired it wrong then. Are you sure @Renfro this wouldn't cause it to blow?
 
Renfro

Renfro

Well-Known Member
Airwalker16 said:
The Larger prong on plugs is not the Hot/Line/+ wire? It's the Neutral/- wire?
I wired it wrong then. Are you sure @Renfro this wouldn't cause it to blow?
Click to expand...
It's alternating current so it wont really matter if they are reversed. The smaller prong is the Hot. Either way its toasted on the DC side. That to me looks like the AC was applied to the DC output.

Only other thing that can cause that is a short on the DC side but I dont see 12 watts causing that severe a burn.
 
Airwalker16

Airwalker16

Well-Known Member
If I did indeed wire the AC side plug to the DC output side accidentally. Which I might have, how would I properly wire power to the one I havent destroyed then? It has Two separate PAIRS of wires (2+/2-)
that all go to a different trace throughole. Would I just connect both negs and pos together and connect to the AC wires? Pos to the SMALL prong wire?
 
dandyrandy

dandyrandy

Well-Known Member
Switching supplies take the line in and rectify it and create a DC buss which gets modulated based upon the voltage and load. On the one picture on the left I see two surface mount bridge rectifiers. Db 1 and two I think. I would expect the AC line to go in this side. Above the board should be some caps for the buss with around a 160 volt rating or more. A picture of the whole top of the board may help. Trace back from the caps and you should see the rectifiers connection. Trace the other side should take you to the AC input and possibly an mov or maybe just a .01 cap.
 
dandyrandy

dandyrandy

Well-Known Member
Question

What are switching power supplies?

Answer

Switching power supplies input a commercial AC power supply (such as 110 VAC or 220 VAC), uses a high-speed semiconductor switching process to convert the input to high-frequency electric power, and yields a direct current (such as 24 VDC).

FAQ01926_01.jpg
 
Renfro

Renfro

Well-Known Member
There is no + or - with AC. The DC side shouldnt have any direct connection to the AC side. If you have some full pics of the un modified board (top and bottom) we can help you get it wired, but basically the AC input should likely be on the other end of the board. I don't see why youd even open it up. Just put 120- 240 VAC power to the AC side and pull DC out of the other side.
 
dandyrandy

dandyrandy

Well-Known Member
The transformer will be smaller than the old 60 cycle supplies. More iron is needed to couple 60 cycle than the switching speed which runs around 50 kcs or higher. I used to work on some out of GE 550 controls which switched at 5kc. More iron. 125 amp at 5 vdc back then weighed around 75 pound. Had to repair them. They failed a lot with 1970's technology.
 
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