old school Ppi pcx-1500

[Perry Babin]

Is it shorted at the arrow?

I see that you didn't push the windings down. Is this an old photo?

 

[Oldskoolamps]

Shorted at what arrow? Yes i took it then watched my fluke as i was moving the windings to see if it went OL.

 

[Perry Babin]

See attached.

 

[Oldskoolamps]

No, i seperated it, Still shorted.

 

[Perry Babin]

It doesn't appear that you pushed the secondary windings down. Slide something like an old credit card between the windings and the core and then under the core as far as possible. Do the same with the primary windings. Does that make a difference?

 

[Oldskoolamps]

I pushed them down as far as they could go and seperated as much as possible,used a cut credit, q-tips & plastic paintbrush handles to seperate & try not scratch/open the coatings. But to no avail, still shorted :-(

 

[Perry Babin]

Can you slide anything between the transformer and the board? I've seen some transformers short to the board.

 

[Oldskoolamps]

I can see that there is clearance to the board, there is a diode underneath it but i pushed it down to be sure it wasn't touching the windings.

 

[Perry Babin]

Desolder the secondary windings one at a time (starting with the smaller, outer ones) to see if any break the short.

 

[Oldskoolamps]

Ah, great idea thanks. & Ok, i will start in the morning.

 

[Oldskoolamps]

So i took 6 out of 8 of them off and it is reading 0ohm to the red wires. 2 of the orange are still attached in the center. The closeup shows a few blackened red wires.

What would my next step be?

and what should i be reading from b+ to the remaining orange secondary center tap wires?

 

[Perry Babin]

I would pull up the remaining two wires. Pull those and the shorted red back as far as possible to get a better look at the damage. It may be possible to use heatshrink tubing to insulate the red windings.

 

[Oldskoolamps]

Ok so i unwound a few turns until the short was eliminated. Should i cover the exposed lengths of the 8 center tap wires and reassemble or what would be the best solution? Is there a coating that i can apply to the exposed lengths that would work better? Or does it not matter as long as the same # of coils is present and the short is eliminated?

 

[Perry Babin]

I would use heatshrink tubing on the wire that you can slide it onto.

Are there any remaining windings on the core that look burned?