How to repair or replace a power transformer?

Sometimes a power transformer can have design issues- such as a spot in the part where a winding makes a bend that causes the insulation to fail. That can lead to windings shorting, the transformer thus running hotter so more windings short and so on.

Sounds like you made the right move!

I blew 5 power trannies on my Sophia 845's. Tech could find nothing wrong with the units. I got sick of paying $400usd for one trannie so I subbed in separate Hammond high tension and 5 volt filament trannies(put in the same one in the original) and have not had the same problem since. Best thing is that the 4 Hammond trannies only cost me $250cad which is about $160usd these days. The hammonds were far heavier as well. 

Sorry to hear that.

You will need to get AC voltages from the other amplifier. I would run the transformer with no load and test its voltages, then hook it up and measure them again so you can give these figures to the transformer vendor you choose.

It may help to provide both transformers to the manufacturer. That way they will have a transformer they can test and one to take apart if need be.

This will likely cost you about $500 by the time you are done, just for the part. A pair of these amps are up on ebay FWIW...

Thank you Bigkidz for the leads on inexpensive power transformers.

Yes to Atmapshpere's question on disconnecting the rectifier. We isolated each power supply and tested and finally eliminated everything in the circuit and tested the transformer alone.

Par-metal in New Jersey sells inexpensive power transformers. Bridgeport Magnetics in Connecticut also sells transformers.

Hmm. Did you disconnect the transformer from the rectifier?

If not your test may not be conclusive.

Thank you for your reply. I will hold onto the electra-print web site information.

Yes, your probably correct that there is another issue. We thought of that but it's good to hear others confirm. We are running a VARIAC in line to test each power supply and monitor the current so we don't damage anything else. The original issue was blowing out the 3amp fuse. Now on the VARIAC we can supply 10volts and the current is already at 1amp. We are going to record all voltages from the good amp this coming weekend and proceed. I am going to open another post asking if anyone has a used transformer and or a Caztech that is being parted out. This amp is at least 20 years old and the company is no longer around. Maybe someone has some used parts that I can purchase. Thanks.

It will likely be more expensive to repair a damaged transformer like that than it will be to replace it, even if the new part is custom-built to do the job. It will be handy to get some voltages from the amp that works, and its likely that you have something else wrong with the amp- its unusual for power transformers to fail on their own.

You might want to talk to Jack Elliano at Electra-Print http://www.electra-print.com/