March 22, 2023 at 12:11 pm #24464Les DicksonCVRS Member
I haven’t seen this before. I’m wondering why there would be a selenium rectifier and a rectifier tube in this radio. It’s a Viking 52-113.I’m planning on replacing the selenium rectifier with a diode and dropping resistor.
Attachments:March 22, 2023 at 3:40 pm #24466John GreenlandCVRS Member
It seems to be a bit of a different configuration for the rectifier tube.
In my estimation based upon following the circuit diagram, the selenium rectifier is there to provide a discharge path for the 80 UF cap that is in series withe the plate of the 35Z5.
Why there is a series cap, is way above my pay grade !
regards John G.March 22, 2023 at 4:07 pm #24467Ralph SpracklinForum Participant
John, you may be on to something. Bcause the 1/2 wave rectifier only produces voltage on each half of every AC Cycle, the DC Voltage is not very clean and the Current flow is not at all stable. So was this a lame and cheap way to keep the tube count of the radio UP, much cheaper than using two half wave rectifier tubes or a single full wave recifier tube. I say this because a selenium rectifier can be used to stabalize current flow. Just trying to stimulate or minds here, and for certain I may be all wet on this concept, strange as it may be. And NO, you won’t be getting a pay raise.
RalphMarch 23, 2023 at 12:36 pm #24468
Hi Guys – pretty sure that is there as a voltage doubler – giving the needed 250 volts at pin 8March 23, 2023 at 12:47 pm #24469
weird numbering on the caps – doublecheck your ac cord wiring polarity on that one – and make sure T1 and associated 330 K resistor are replaced. I always add a fuseholder and fuse to the hot side as well.March 23, 2023 at 4:06 pm #24474John GreenlandCVRS Member
By George ( or actually Steve in this case)
I think that you have hit the nail on the head with the doubler idea. It does explain the series cap.March 23, 2023 at 7:26 pm #24476
What will this look like with the neon indicator lit up – I assume it is exposed on the front panel ?March 23, 2023 at 7:29 pm #24477
Radiomuseum has this info https://www.radiomuseum.org/r/eatonco_viking_52_113.htmlMarch 24, 2023 at 9:31 am #24481Les DicksonCVRS Member
Thanks to everyone for the replies to this topic.
- I’ve never seen a configuration like this before so I appreciate all your input.
- The neon indicator is in the base of the unit – centred – in the toe kick area. It would be visible when the cabinet doors are closed.
- The capacitor designations are different where T.1/400 means tubular 0.1 MFD at 400 Volts (E for electrolytic and M for mica)
Attachments:March 25, 2023 at 5:04 pm #24499Ralph SpracklinForum Participant
Seeing we are on th topic of Selenium Rectifiers, and if we are not yet confused enough about those smelly items, I thought Iwould give you all something to ponder.
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