RA-103 Vertical Transformer Issues

[Chris K]

My original is open on the yoke side of the winding. Turns out the same is true in the replacement from my parts chassis. Is this a common failure in these sets? I cant find any data on resistance values for the coils so having something wound or finding something close will be difficult. Hopefully I can find a good one somewhere.

[Penthode]

Because the break is on the secondary which will use heavier gauge wire, you should examine the transformer for an obvious break near the terminals or where the secondary wires attach. Normally the secondary does not open.

[Chris K]

I removed the coil wrap and tested both by the wire/coil solder point and the secondary is open. I can see the coil wire ends and they’re firmly soldered to the wires. The break has to be internal or I’m doing something very wrong.

[jr_tech]

Originally Posted by Chris K

My original is open on the yoke side of the winding. Turns out the same is true in the replacement from my parts chassis. Is this a common failure in these sets? I cant find any data on resistance values for the coils so having something wound or finding something close will be difficult. Hopefully I can find a good one somewhere.

or, from earlier thread:

Originally Posted by Chris K

Found my problem...I think. The vertical sweep output transformer has an open coil on the vertical deflection amp side. The set was only drawing 2 amps when it started to smoke so I better make sure I didn't just cook it by leaving it powered up for 10 seconds with an upstream issue or if it was gone from jump. Black tar was oozing out of it but it didn't look too bad. I have another one from a parts chassis but I don't want to cook that one too.

I’m confused... what is the actual problem? Are any windings shorted to the transformer frame?
jr

[bandersen]

I am as well. It would make it easier on us all if you had one thread for the whole project.

[Chris K]

Yeah I'm confused too. Has anyone ever heard of this? I'm using a Klein Tools multimeter in my work. Not a Fluke by any means but it was rated a good tool for the money in an electronics website. A conversation with a fellow collector made me think, why don't I get an opinion from another piece of test gear so I used my VTVM in ohms mode. There it was, a resistance reading in the secondary winding. I used it on the parts chassis VOT and again, the secondary ohms out. Now why the hell would my multimeter, that has never had an issue and never given me bad continuity results be consistently unable to read the secondary in not just one...but THREE transformers? Sometimes Friday nights in the shop are very aggravating!!

[Chris K]

Originally Posted by bandersen

I am as well. It would make it easier on us all if you had one thread for the whole project.

Will do...I'll tell a tale in a separate thread with pictures up to where I am and then move forward. Thanks.

[jr_tech]

Originally Posted by Chris K

Now why the hell would my multimeter, that has never had an issue and never given me bad continuity results be consistently unable to read the secondary in not just one...but THREE transformers? Sometimes Friday nights in the shop are very aggravating!!

I suspect that the ohm range on the Klein got blown out... check if it can read accurately some known value resistors... does it read zero ohms if you short the test leads together when a ohm range is selected?

jr

[Polaraligned]

Originally Posted by Chris K

Now why the hell would my multimeter, that has never had an issue and never given me bad continuity results be consistently unable to read the secondary in not just one...but THREE transformers?

Some digital multimeters will fail testing a large inductor (that is what the meter sees) due to the way they sample and the higher inductance of what you are measuring.

[Electronic M]

If the vertical transformers are bad you may want to ask Banderson if he needs the vertical transformers out of the Stromberg Carlson badged RA-103 I'm selling him. The vertical output transformer was good last time it had HV and the osc was new. The set started burning up it's H lin coil and I found a better chassis cheaper and gave up on it.