Color TV Boost Rectifier

[bhegges]

Question - I am working on a 60s era color tv which uses a boost rectifier in the HV circuit. Per SAMS one replacement option is a ECG119. This is a selenium rectifier, do I need to be worried about the reliability of a NOS part or should I look to use a new production fast recovery silicon diode? There are thousands of diodes to pick from, what about this one, it looks to be a very fast diode and specs look to exceed the original part: https://www.digikey.com/en/products/...TE638/11645422.

Circuit:


Here are specs for the recommended selenium rectifier replacement:


and also:

[zeno]

Thats all we used for years. I see no reason not to use NOS.
I would change C119 with a brand new one while you are there

73 Zeno
LFOD !

[DavGoodlin]

The 119 pictured is for a solid state TV with lower boost than tube TV sets. Use the ECG118 equivalent, you need the PRV rating higher than 5,000 volts.

Would a common focus rectifier like in a CTC15 work?

[Tom9589]

I would go with the 119. The 118 has 11 times the forward voltage drop of the 119 and the max current rating of the 118 is 1/4 the rating of the 119. I think you will also find a notable difference in physical size.

[Electronic M]

Originally Posted by DavGoodlin

Would a common focus rectifier like in a CTC15 work?

The CTC15 clones I've had used significantly different SS stick rectifiers in the boost than the SS focus rect. The boost had lower PIV and higher current. About 10 years ago Radio shack used to carry 2KV PIV 1.5A diodes and I'd use 2 in series. The TV that had that fix got used daily for around 8 years and still works fine.

[dieseljeep]

Originally Posted by zeno

Thats all we used for years. I see no reason not to use NOS.
I would change C119 with a brand new one while you are there

73 Zeno
LFOD !

I only remember replacing two in 20 years of repairing.
Focus rectifiers were a different story. Breaking the bad one open, there was a number of tiny selenium disks inside.

[bhegges]

To update the group I did replace the boost rectifier with a NOS ECG119 selenium rectifier as was identified in the SAMS as a replacement part. I suspect the original part was failing as after replacing the 1000v boost source came up from a previously measured 871 volts to now 1020 volts. Further repair details are in my Packard Bell thread.

The root of my question was around using a selenium rectifier, there is a lot of discussion about how these go bad both from use and possibly from age.