1956 Admiral solid state HV rectifier modification

[JCFitz]

Since I have been unable to replace the high voltage rectifier cup in the 1956 Admiral 20Y4E I have posted about in the past I have followed a suggestion to convert it to solid state.

I don't have a load of old tv chassis or parts but I did have an old stick rectifier from a solid state color tv I junked years ago.I did utilize the old HV cup as a holder and to help insulate the rectifier from the chassis. I knocked the old tube socket which was glued in place inside the cup out and found a nylon washer that fit in the hole and held the stick rectifier snugly in place.

To insulate the output I put both the focus rectifier rubber cap and hv rectifier rubber cap from a dead Philips/Magnavox flyback concentrically over the bare male part of the HV stick rectifier. to make doubly sure that it was sealed from air and possibility of corona I also used a thick rubber piece salvaged from an old Philips/Magvavox HV section on top of the output of the outer cup and new HV lead. All of this was covered in heat shrink.

The old heater leads are covered with heat shrink and tied behind the chassis if anyone ever wants to convert it back to a tube rectifier. I really went out of my way to insulate the rectified HV completely from open air.


http://www.youtube.com/watch?v=_KlBzI3zcpM

I'm happy to say this works great as far as I can tell. I heard a couple of ticks when HV first came up and then blissful silence except for the normal sounds of a tube tv chassis operating.I can stand in back of it and listen and no ticking or corona of any kind.

I was kinda worried about not having enough hv with a color rectifier but actually I may have more. I got plenty of brightness and it only blooms slightly if I turn it all the way up. It did that before so no worries there. I am wondering if I'm a little high on the HV.I'll have to bring home the HV probe from the shop to check it.

The schematic calls for 14.5 kv.does anyone have specs for maximum hv for a 21ALP4? Of course I don't know what my HV is running yet.It may be brighter because the ticking was pulling down the HV.Also that intermittent vertical height jump has not reared its ugly head at all.