Author Topic: High Voltage supply for old CRT tube ?  (Read 1523 times)

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Offline lordvader88Topic starter

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High Voltage supply for old CRT tube ?
« on: March 16, 2018, 01:09:08 am »
I have a RCA-WO33A CRT oscilloscope from he 1960s, and the transformer is busted, I've yet to take it apart, maybe its fixable. But if not, what are some ideas to make 600-700V at 10-20mA I think.

I have 3-4 CRT TV PCBs with SMPS, and 1 from the 1970's, not sure if it's linear or switching kind. I have 2 microwave transformers that could maybe be rewound ? Or make a SMPS from scratch ? For now I don't want to spend much money, and I guess any suitable off the shelf transformer would be +$50 easy w/shipping
 

Offline AutogolazzoJr

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Re: High Voltage supply for old CRT tube ?
« Reply #1 on: March 16, 2018, 01:54:18 am »
I don't think a microwave transformer would get anywhere near the voltage you need. It would probably saturate. Perhaps an ebay flyback transformer?
 

Offline Rog520

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Re: High Voltage supply for old CRT tube ?
« Reply #2 on: March 17, 2018, 12:28:42 am »
You could probably find a cheap, used plate transformer (for vacuum tube equipment) at auction. Or find a transformer with a more common, lower voltage secondary and use a voltage multipler to get your required output. An SMPS in a scope is a bad idea unless it's specifically designed to be very low noise.
 

Online vk6zgo

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Re: High Voltage supply for old CRT tube ?
« Reply #3 on: March 17, 2018, 06:29:52 am »
Some of the older radios (from the 1930s & maybe early '40s) used  285v a side " or even "385v a side" transformers with tube full wave rectifiers.
The full voltages of these centre tapped secondaries are 570v & 770v respectively.
Used with a bridge rectifier, these would give dc voltages of the order you require.

1950s & 1960s  transformers usually had secondaries of from 450 v to 480v total, but would work with a voltage multiplier.

Unfortunately, these smaller transformers aren't as common in the USA as in Oz, as they used transformerless construction for most of their "mantel" radios.
 


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