Sansui G-7700 with blown transformer

[bdbell]

Have a G-7700 on the bench that won't power on, Red/Brown wires that go into the primary side show no continuity...fuses are all good, and when I turn the switch on there's 120v where the red/brown wires go into the and primary, but nothing coming out any of the secondary's - which all show continuity.

I know it is pretty rare for a transformer to blow but I totally disconnected it and still no continuity on the primary - can't get more definitive than that! Need to remove it and see if maybe there's a wire broken on the outside but doubtful.

Client was told that it may be dead so has already contacted someone willing to make one - but minimum 5 order! I just don't see there is a lot of demand for them so was thinking it would be better to find someone to rewind it, it's not potted so shouldn't be too difficult - but then not something I have any experience in so looking for advice/feedback.

thanks

 

[Hyperion]

From what I can see - you are measuring an 'open circuit' between the Red & Brown wires that come directly out of the transformer, this is a good enough test, to prove you have a faulty transformer.

Some transformers have a thermal fuse tucked into the windings, which can sometimes blow whether the transformer gets too hot or not. The fuse is sometimes not too difficult to access. However, replacement of the fuse, (or if this is not possible a 'rewind'), is best carried out by someone used to performing such tasks.

I fairly recently discovered a defective transformer in a Sansui AU-719, which the owner took to a transformer rewind specialist that I found for him. I tested the transformer when it was done and it was perfect! - I had difficulty seeing any trace of work being having been done on the transformer - (i.e. perhaps not a rewind, maybe just a thermal fuse replacement). I feel sure that such rewind services exist near you.

Good luck!

 

[bdbell]

I should have moved things around a bit more so it's a little easier to see - I actually tried several of my meters just to make sure and it's totally open. There is absolutely no smell at all so I tend to think you are right about a fuse or something simple - but not something I want to learn on so I will see if I can find someone here in the Toronto area...gotta be someone fairly local.

Thanks!