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KB RV30

Black & White Television

Last Post by Norman-Raeburn 5 years ago

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Norman-Raeburn

(@norman-raeburn)

Posts: 174

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Hi Folks, I have been slowly restoring this set for a friend and this afternoon I was reminded why I don't do it for myself now let alone anyone else. The lopt failed while I was running the set, the primary winding has melted which is quite common in this type of transformer now. I have a spares set which doesn't really look much better with the pitch covered windings. I will pass some current through the winding to dry it out before fitting. I have a feeling I will need to source something else and try to fit that. I of course have no spares now as I have disposed of most of my tv spares. If you think I sound disgruntled then it's a good job you weren't in my workshop this afternoon, the air was blue. I thought I was close to the end of this restoration ha ha, somebody had other ideas. Norman

Posted : 14/06/2019 4:43 pm

Nuvistor

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That’s a beggar, some LOPTX ‘s *were not that reliable when only a few years old, now after 40-50 years its a gamble with any of them.

*Bush TV161 for one type, no doubt there were others.

Hope the spare dries out and does the job.

Frank

Posted : 14/06/2019 7:29 pm

Norman-Raeburn

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Just a follow up to this, the spare lopt I had works for a short while but runs very hot and the width comes in. I did try running some current through the windings to drive out any damp but this hasn't helped.

Now for the hard part, does anyone have a lopt they would part with or something else I could bodge in (I believe a BRC jellypot is a likely candidate). I have nothing myself as I gave almost all of my spares away. Any help gratefully received. Norman

Posted : 24/07/2019 7:53 pm

PYE625

(@pye625)

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Hi Norman, the syptoms are not too dissimilar with that of the RBM transformer I had fun with here....

https://www.radios-tv.co.uk/bush-murphy-lopt/

If the construction and insulation of the overwind is similar to that of an RBM lopt, then it might be worth investigating. The insulation of the primary should be ok as the voltages here are much lower of course.

To understand the black art of electronics is to understand witchcraft. Andrew.

Posted : 24/07/2019 8:21 pm

Norman-Raeburn

(@norman-raeburn)

Posts: 174

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Hi Andrew, Thanks for the reply, this set is 405 only so won't have the extra winding. I didn't suspect the overwind as it's the primary getting hot but the overwind could be loading the primary. I too had something similar with a Bush TV115? and I cut the overwind off and fitted a tripler or doubler and it's been fine. I may have to examine this more closely but I am getting lazy and want this moved. I will have another look tomorrow. Norman

Posted : 24/07/2019 8:30 pm