My friend handed me off some lighting equipment, and some of which were working fine and some of which immediately blew their fuses. I believe I've narrowed it down to the toroidal transformer inside - I'd disassembled the unit down to just AC -> Fuse -> Switch -> Transformer, and the fuse immediately blew. I compared the resistance between the transformer from the working unit and dead unit, and found similar secondary resistances, but a resistance of 52Ohms on the good unit, and 9 Ohms on the dead unit.
I'd love to fit in a new transformer, but unfortunately, these don't appear to be easily available - 27W 115VAC input and 11VAC and 7VAC outputs (although board is marked for 12VAC and 7.5VAC, which corresponds to the transformer's output at maximum main's voltage (125VAC). A custom unit from China would cost $60 each, which is the majority of the unit's worth. Would The following procedure work?
- Unwind Secondary, then primary.
- Use calipers to measure gauge of wire, and buy the appropriate wire gauge
- Measure length of primary and secondary wires. Since the lengths are identical, the turns should be identical for the most part. Replace the secondary winding preemptively so don't have to worry about the 12 year old coating dying on it too.
It just seems... too simple. I'm a mechanical engineer, not electrical, but is that really all there is to it?
EDIT: Thanks y'all, after thinking about my (new) options, I think I'm going to buy a new 7V transformer from antek for $11 and transplant the 11V secondary windings from the old transformer to the new one. Sound like a plan?