HV transformers: Difference between revisions
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In many classic scopes, the high voltage transformer that supplies the cathode, blanking, and anode voltages has a tendency to break down. | In many classic scopes, the high voltage transformer that supplies the cathode, blanking, and anode voltages has a tendency to break down. | ||
This is mostly because of aging of the potting material used for the high-voltage windings. | This is mostly because of aging of the potting material used for the high-voltage windings. | ||
When this happens, the transformer will run very hot because dielectric loss is too high. | |||
It is a thermal runaway. | |||
Currently, the only options when this happens are to find a similar transformer from another scope, | Currently, the only options when this happens are to find a similar transformer from another scope, | ||
or to get a rewound transformer. | or to get a rewound transformer. | ||
A second option is to improve the cooling of the high voltage transformer. | |||
This approach has been tested with success on a 556's HV transformer. | |||
The same HV transformer, part number 120-0308, is used in the [[543|543B]], [[544]], [[545|545B]], [[546]] and [[547]] . | The same HV transformer, part number 120-0308, is used in the [[543|543B]], [[544]], [[545|545B]], [[546]] and [[547]] . | ||
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<gallery> | <gallery> | ||
File:KeepcoolHV.JPG | | File:KeepcoolHV.JPG | Seconds option: cooling with an aluminum block (heat sink) | ||
</gallery> | </gallery> | ||
Revision as of 09:45, 25 May 2015
In many classic scopes, the high voltage transformer that supplies the cathode, blanking, and anode voltages has a tendency to break down. This is mostly because of aging of the potting material used for the high-voltage windings. When this happens, the transformer will run very hot because dielectric loss is too high. It is a thermal runaway.
Currently, the only options when this happens are to find a similar transformer from another scope, or to get a rewound transformer.
A second option is to improve the cooling of the high voltage transformer. This approach has been tested with success on a 556's HV transformer.
The same HV transformer, part number 120-0308, is used in the 543B, 544, 545B, 546 and 547 . Chuck Harris, who frequents the Yahoo Tekscopes forum, has rebuilt several 120-0308 transformers with good results.
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Seconds option: cooling with an aluminum block (heat sink)
