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 Post subject: selenium rectifier
PostPosted: Feb Sat 05, 2011 7:38 pm 
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Joined: Feb Sun 10, 2008 4:51 am
Posts: 144
Hi to all i have a question. It is this what do i replace a selenium rectifier part no. 212-2 with ?. I want to use a diode if i can it is in a radio. All help appreciated.

Zane


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 Post subject: Re: selenium rectifier
PostPosted: Feb Sat 05, 2011 8:03 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1134
Location: Dallas, Texas USA
Zane wrote:
Hi to all i have a question. It is this what do i replace a selenium rectifier part no. 212-2 with ?. I want to use a diode if i can it is in a radio. All help appreciated.

Zane

A very qualified - yes.

What sort of voltage and wattage is applied to it?
This would be VERY important in picking which diode would be a good match.

However, in general, so long as it's pulling UNDER 1 AMP of current, you can use a 1N4005, 1N4006, or 1N4007. These should be available at Radio Shack.

Note that the 'modern' diode drops less voltage across it than the old selenium rectifier. So you may need to include a big, sand-style resistor in series to drop the voltage a bit. Usually a 5 or 10 Watt resistor with a value of around 150 to 200 ohms will do in the typical radio application. This will be just enough to return the voltage coming OUT of the diode to about what it was with the old selenium rectifier.

This resistor will probably get pretty warm, even hot to the touch, but must not 'smoke' or turn dark or discolor.

Heavy Disclaimer Here: Be VERY careful here, as these are mains voltages and you can hurt or kill yourself and / or burn down your house. This is a general answer and not knowing more about your specific project, I'd be doubtful about any more specific answer.

Mike Y
Dallas, Texas


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 Post subject: Re: selenium rectifier
PostPosted: Feb Sat 05, 2011 8:17 pm 
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Joined: Feb Sun 10, 2008 4:51 am
Posts: 144
Mike Yancey wrote:
Zane wrote:
Hi to all i have a question. It is this what do i replace a selenium rectifier part no. 212-2 with ?. I want to use a diode if i can it is in a radio. All help appreciated.

Hi Mike this diode goes to replace a Zenith part no. 212-2 selenium rectifier in the Zenith model 4G903 radio. The power out put has a 100 volts after being drop through resistors. The Zenith rectifier has less that 80 volts coming out of it. It also has a burnt spot on one of the fins of the rectifier. And i dont like the way it checks out on my meter as the ohms go fordward and backwards. I hope this helps out a little.

Thanks
Zane

Zane

A very qualified - yes.

What sort of voltage and wattage is applied to it?
This would be VERY important in picking which diode would be a good match.

However, in general, so long as it's pulling UNDER 1 AMP of current, you can use a 1N4005, 1N4006, or 1N4007. These should be available at Radio Shack.

Note that the 'modern' diode drops less voltage across it than the old selenium rectifier. So you may need to include a big, sand-style resistor in series to drop the voltage a bit. Usually a 5 or 10 Watt resistor with a value of around 150 to 200 ohms will do in the typical radio application. This will be just enough to return the voltage coming OUT of the diode to about what it was with the old selenium rectifier.

This resistor will probably get pretty warm, even hot to the touch, but must not 'smoke' or turn dark or discolor.

Heavy Disclaimer Here: Be VERY careful here, as these are mains voltages and you can hurt or kill yourself and / or burn down your house. This is a general answer and not knowing more about your specific project, I'd be doubtful about any more specific answer.

Mike Y
Dallas, Texas


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 Post subject:
PostPosted: Feb Sat 05, 2011 9:06 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 12549
Location: Mpls, Minnesota
If you have 100 volts B+ the selenium is fine, you can't check a selenium with a ohm meter. The electrolytics and paper capacitors should also be replaced. Don't try to replace any tubes when the radio is turned on or you will burn the tubes out.

Dave


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 Post subject: Re: selenium rectifier
PostPosted: Feb Sun 06, 2011 12:38 pm 
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Joined: Feb Sun 10, 2008 4:51 am
Posts: 144
Mike Yancey wrote:
Zane wrote:
Hi to all i have a question. It is this what do i replace a selenium rectifier part no. 212-2 with ?. I want to use a diode if i can it is in a radio. All help appreciated.

Hi Mike a big thank you for the information you sent my way on replaceing the selenium rectifier. The Zenith part no. 212-2 by useing a 4007 diode. Have a super day in Dallas Texas.

Thanks
Zane

Zane

A very qualified - yes.

What sort of voltage and wattage is applied to it?
This would be VERY important in picking which diode would be a good match.

However, in general, so long as it's pulling UNDER 1 AMP of current, you can use a 1N4005, 1N4006, or 1N4007. These should be available at Radio Shack.

Note that the 'modern' diode drops less voltage across it than the old selenium rectifier. So you may need to include a big, sand-style resistor in series to drop the voltage a bit. Usually a 5 or 10 Watt resistor with a value of around 150 to 200 ohms will do in the typical radio application. This will be just enough to return the voltage coming OUT of the diode to about what it was with the old selenium rectifier.

This resistor will probably get pretty warm, even hot to the touch, but must not 'smoke' or turn dark or discolor.

Heavy Disclaimer Here: Be VERY careful here, as these are mains voltages and you can hurt or kill yourself and / or burn down your house. This is a general answer and not knowing more about your specific project, I'd be doubtful about any more specific answer.

Mike Y
Dallas, Texas


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 Post subject:
PostPosted: Feb Sun 06, 2011 1:52 pm 
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Joined: Jul Mon 26, 2010 8:30 pm
Posts: 27651
Location: Annapolis, MD
Zane;

Why are you quoting people's replies, but not adding anything?


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 Post subject: selenium rectifier
PostPosted: Feb Sun 06, 2011 2:33 pm 
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Joined: Feb Sun 10, 2008 4:51 am
Posts: 144
pixellany wrote:
Zane;

Why are you quoting people's replies, but not adding anything?



Sorry about that i guess i click the wrong button i will try to do better.

Zane


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 Post subject:
PostPosted: Feb Sun 06, 2011 2:54 pm 
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Joined: Jul Mon 26, 2010 8:30 pm
Posts: 27651
Location: Annapolis, MD
I just noticed that you had in fact added something---but it was inside the quote. So---if you quote something---2 suggestions:
cut out everything except what you want to respond to, then put your reply outside the quote.

Good luck!!


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 Post subject:
PostPosted: Feb Sun 06, 2011 8:28 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 12549
Location: Mpls, Minnesota
Or don't use the "quote" at all

Dave


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 Post subject: selenium rectifier
PostPosted: Feb Sun 06, 2011 9:37 pm 
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Joined: Feb Sun 10, 2008 4:51 am
Posts: 144
Alright i will try to explain what problem i am having with a Zenith radio model 4G903 chassis 4F40. I posted some earlier problems that i was having with this radio. When i purchase it i found that someone had been in it before i got it. They had removed the 4 section electrolytic from the circuit, and did not replace it even if it was bad. Did not even leave it with the radio when they got rid of it. Left the rats nest of wires, caps, and resistors for some one else to fret with. So early help from some of you men i was able to get a schematic, and find out what the mfd, and voltage was on the 4 individual cap's i used . With the circuit put back togather by me who is new at restoreing old radios, my problem now is i dont have no sound. nor buzzing or anything coming out of the speaker. Tubes check good, off-on switch is working i have coming off of the (selenium rectifier) around 65 volts dc going to resistors 8,9, and 10. I put in a 1n4007 diode to replace the Zenith rectifier 212-2 it boosted my dc voltage up to around 70 volts dc. Going across the resistors 8,9, and 10 to where i am suppose to have 100 volts B+ and 7.5 volts for the filament voltage i have also there around 65 to 70 volts dc. That is coming off of resistor 10 through the WH-BL wire to switch 1 on terminal 9# to terminal 8# then up to pin 7# of tube 3V4 with 7.5 volts dc to filament string, as i said no voltage ac or dc. I checked out the continuity on the filament string from tube socket to tube socket, found it good. I need all the help i can get on this one, to see what is wrong why the tubes dont have the filament voltage going to the tubes. Will appreciate all the help you can pass on to me.

Thanking You All
Zane


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 Post subject:
PostPosted: Feb Sun 06, 2011 9:44 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 12549
Location: Mpls, Minnesota
You are also posting at nostalgia air, and have been getting some good advice there. You should probably continue there.

http://www.nostalgiaair.org/Forums/Mess ... 092535.htm


Dave


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 Post subject: selenium rectifier
PostPosted: Feb Sun 06, 2011 10:03 pm 
Member

Joined: Feb Sun 10, 2008 4:51 am
Posts: 144
easyrider8 wrote:
You are also posting at nostalgia air, and have been getting some good advice there. You should probably continue there.

http://www.nostalgiaair.org/Forums/Mess ... 092535.htm


Dave




Hi Dave you are so right i have been getting some good advice from nostalgia air I just thought i could also get some more good help from you all.

Thanking You Again
Zane


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