switch mode supply transformer, leads to nowhere

[jojo69]

Stumped troubleshooting a Cetek battery charger here. I am pretty weak on switch mode supplies.

There were 2 terminals on the transformer that were open to any other xfmr nodes so I figured that was probably the problem.

Unwound the xfmr and actually those leads just go a couple cm in next to shield wrap layers and end...what the actual *&%#?

I pine for the days of simple pass regulated linear supplies where I understood what was going on. Can anyone explain what is going on here?

[retiredcaps]

Re: switch mode supply transformer, leads to nowhere

Clear focused pictures of both sides of the pcb and a clear description of what is wrong or not working with the battery charger helps us help you.

[Joe Black]

Re: switch mode supply transformer, leads to nowhere

I find THIS GUIDE to be on-spot, short and to the point when it comes to basic troubleshooting SMPS.

[jojo69]

Re: switch mode supply transformer, leads to nowhere

Sorry if I was not clear guys, I have pretty much given up on this one, having unwound the transformer,. I am just trying to learn at this point.

This was really a more general question about these nodes to nowhere. All I can figure is that they provide some sort of sense signal of current in the transformer?

[budm]

Re: switch mode supply transformer, leads to nowhere

'There were 2 terminals on the transformer that were open to any other xfmr nodes so I figured that was probably the problem.' If we see the pictures of the board we probably can tell if those two pins are not used. You might as well upload the pictures if you want to learn how this power supply functions.

[jojo69]

Re: switch mode supply transformer, leads to nowhere

lol, OK, it is in a few pieces at the moment

[jojo69]

Re: switch mode supply transformer, leads to nowhere

OK, got back to the bench.

First one, top of board, input to the left, the stuff outside the heatsinks is pretty conventional.

2nd one bottom side input

3rd one bottom side output

4th, unwound XFMR, yu can see the short wire I am asking about

5th here it is taped back down with the shield layer ready to go back over it

edit/ hold on, I'm getting 500 from the server

[jojo69]

Re: switch mode supply transformer, leads to nowhere

trying again

[jojo69]

Re: switch mode supply transformer, leads to nowhere

and the xfmr

[budm]

Re: switch mode supply transformer, leads to nowhere

Can you please show the pictures of the whole board, top side and the bottom side?

[jojo69]

Re: switch mode supply transformer, leads to nowhere

thanks for the answer!

not without dismounting both heatsinks, all of the input; fuse, thermistor, rectifiers, choke and caps are hidden under the input switcher heatsink on the left. Most of the output filter is hidden under the other one.

I will do that next bench session

[budm]

Re: switch mode supply transformer, leads to nowhere

So far it looks like the primary side has two windings, the secondary side has one winding with center tap to feed the full wave rectifier diode D14 (dual diode common Cathode).

[jojo69]

Re: switch mode supply transformer, leads to nowhere

Sorry about that, those heatsinks take a frightening amount of heat to get off. The input side was not so bad because I had it off before and just tacked it back on, but the output sink was a bear...2 iron job, need 3 hands.

I hope these views work better

[CapLeaker]

Re: switch mode supply transformer, leads to nowhere

I have a few of those Ctek's. Not one of them has failed yet. Having said that, with my luck I'll go in the garage later and everything is dead. What was wrong with it first place and how long did you have used it?
Not too long ago, I posed a thread repairing a Motomaster switching battery charger, as water went into it somehow.

[jojo69]

Re: switch mode supply transformer, leads to nowhere

bunch of the input side silicon was failed short, 2 diodes, a zener and the switcher as I recall

replaced all that and it worked for a day, now something else is wrong with it