Electrical Connections

[supton]

I don't see any traces on the topside of the board, so it looks like a singled sided board. Should be easy-peasy to pop that thing out. You'll want a solder sucker to do that. Medium tip? I usually use a small one to do most work, but here a bit larger than pencil would work better, more heat transfer.

You could do it with solder wick but eh, sucker is the way to go.

I do think the transformer is junk and assuming it's not $50 I would be swapping it out. Anyhow, I don't blame you if you want to source that out, I wouldn't say soldering is hard, but it is a skill to be learned, and if you're not going to use it again, well... I know friends will hit me up for soldering work. [Some day I might go get trained, we talk about it at work from time to time.]

 

[ecotourist]

I don't see any traces on the topside of the board, so it looks like a singled sided board.

Looks like the pins go through the board and are soldered at the back. I assume that's what you mean by a single sided board.

 

[supton]

Looks like the pins go through the board and are soldered at the back. I assume that's what you mean by a single sided board.

Yes, and it's way easier to rework. Easier to lift a pad too, as you lose the copper in the hole to hold it down, so there's that.

 

[Pablo]

I honestly wouldn’t replace the transformer until confirmed short but would rather find out why it is working hard.

What does it power? Is something wrong downstream?

Need a current draw

I’m thinking the lousy connections led to all this

 

[ecotourist]

I’m thinking the lousy connections led to all this

There may have been a poor connection somewhere but there wasn't anything visible. On the other hand it's working much better now and all I've done is clean connections.

 

[ka9mnx]

What is the 12V driving?

The 12v transformer is driving the switches and control circuit. Those switches are not designed for 120vac. Somewhere in there is a bridge diode circuit because I'm unaware of any IC's that run on ac current. And yes, transformers can get hot to the touch.

 

[Pablo]

The 12v transformer is driving the switches and control circuit. Those switches are not designed for 120vac. Somewhere in there is a bridge diode circuit because I'm unaware of any IC's that run on ac current. And yes, transformers can get hot to the touch.

I figured the control circuit, and yes switches make sense. Yes the AC would need to be rectified.

Sounds like the cleaning is helping. I would get it a couple more cleaning cycles, blow it all out and call it good.

 

[ecotourist]

I figured the control circuit, and yes switches make sense. Yes the AC would need to be rectified.

Sounds like the cleaning is helping. I would get it a couple more cleaning cycles, blow it all out and call it good.

A lower voltage for the switches and control circuit makes sense to me too.

I'm planning to take the motor/fan units out and give everything a good cleaning. Considering how hard they are to take out, I'm sure it's never been done and this unit could be 20 years old.

The warm/hot transformer gives me pause for thought too. I'd be happier if I could find a replacement for this one. We'll see if I can turn up a supplier who will sell one at a reasonable price. One supplier offers them with a minimum order of 10. And I found one in Europe that would have cost something like $125 with shipping. I'm looking for something more like $10-15 plus shipping.

And thank you @ka9mnx for your comments.