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 Post subject: selenium rectifier and shock hazard
PostPosted: Jan Thu 24, 2019 12:49 am 
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On my G500 Zenith the selenium rectifier probably needs to be tossed and the silicone diode installed , so I've seen a set-up for the H500 but it doesn't look like it will work. Does anyone have a silicone diode diagram setup for the G500?

Shock hazard; since the radio does not polarized plug originally, what do I need to make this 100% safe from electrocution? I dont want to be fried. :shock:

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 Post subject: Re: selenium rectifier and shock hazard
PostPosted: Jan Thu 24, 2019 1:33 am 
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If the radio is working properly after replacing the defective capacitors and electrolytics and the voltages are correct leave the selenium in place. I have many transoceanic's and they all have the seleniums in place.

If you really want to make your radio safe from electrocution cut the cord and put it on the shelf. Your radio is safe as it is. Look around your house, how many appliances use a three wire grounded cord??

Dave


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 Post subject: Re: selenium rectifier and shock hazard
PostPosted: Jan Thu 24, 2019 6:35 am 
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Joined: Sep Thu 23, 2010 6:37 am
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Location: Powell River BC Canada
Your radio is changed over from house current to batteries by sticking the existing
power plug into slots in the radio. If you want to make your radio 100 % shock safe
buy a small isolation transformer with a 3 pin power cord. Plug your G500 into that
with the existing line cord.

Bad Restorer show a selenium replacement .

http://www.renovatedradios.com/articleP ... nGuide.pdf

Attachment:
Zenith G500 transfer.JPG
Zenith G500 transfer.JPG [ 19.02 KiB | Viewed 1253 times ]

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 Post subject: Re: selenium rectifier and shock hazard
PostPosted: Jan Thu 24, 2019 7:08 am 
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Why don't you think the silicon diode replacement method for the H500 would work on a G500? They have a power supply section that is practically identical.

Nothing is 100% safe. Adding a polarized cord is not a magic cure for hot chassis sets as outlets are not always wired correctly, also this radio has a floating ground so if the hot side of the AC line were connected to the chassis and you grabbed the chassis and some ground contact, the current is limited through a capacitor so it is non-lethal. Of course, the best safety is the one between your ears.

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 Post subject: Re: selenium rectifier and shock hazard
PostPosted: Jan Thu 24, 2019 7:21 am 
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walz wrote:
On my G500 Zenith the selenium rectifier probably needs to be tossed and the silicone diode installed , so I've seen a set-up for the H500 but it doesn't look like it will work. Does anyone have a silicone diode diagram setup for the G500?

Shock hazard; since the radio does not polarized plug originally, what do I need to make this 100% safe from electrocution? I dont want to be fried. :shock:

PROBABLY needs to be tossed? What are you basing that assumption on? I have plenty of 3 way portables still using selenium rectifiers, and NP. As was stated above, if the set is working OK, leave it as-is.

And believe me, you won't get electrocuted if you do inadvertently have both hands on the wrong components while it's energized. What you will get though, is a shock that might knock you on your tushy, and which you won't forget. Don't ask me how I know this, as an irrefutable fact...

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 Post subject: Re: selenium rectifier and shock hazard
PostPosted: Jan Thu 24, 2019 12:10 pm 
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Just measure the B+ voltage under the line input and operating conditions in the service literature. If the DC is within 10% of normal, the selenium is fine and can be left alone.

Polarized plugs are supposed to be used where there is a chance the user may inadvertently contact live metal. Think of a lamp with an ordinary Edison base light bulb. As you unscrew the bulb it is possible to inadvertently touch the metal shell of the bulb base, so it would be safer if that could be on the neutral side of the line. Since there is no metal at line potential that can be touched when the G500 chassis is in its cabinet, a polarized plug won’t make it safer. What it will do is make the radio harder to use, when you find an outlet with mord noise on one side than the other and you can’t flip the plug.

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 Post subject: Re: selenium rectifier and shock hazard
PostPosted: Jan Thu 24, 2019 5:31 pm 
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Wow this place is a treasure trove of information, I really struck gold here.

Thanks, I'm reading everything you posted, it is really great information.

I have four trans oceanic radios, all are from the 1940-1950 era and they are my museum pieces. So this is not a shelf queen, it was purchased with the sole intent on being used in a disaster preparedness kit. I've restored the case 100% with new wood, covering, glue, you name it. The case is exactly like the factory except it is more rugged. The chassis is my rebuild ground up, I've ripped out all of the resistors installing new ones, everything is new. The capacitors were a challenge, some are ceramics, and from my study they stay put, but everything was replaced. The builder chassis was semi complete, who ever had it before me butchered some things, however I have my G500 chassis as a road map replacing anything that was missing, replacing the resistors, capacitors, bare wires, brokenvwires, tracking down wires, you name it it's checked out for accuracy. The string for changing stations is replaced.

I'm still trying to re-stuff the capacitor and getting all of the new capacitors inside the can may be impossible, so I'll stuff as much inside that I can. The left over capacitor will go inside the chassis.
On replacing the Celenium Rectifier to silicon diode, the "builder chassis" that I have was missing some parts. Since this is a daily user radio I've put upgrades inside the chassis. A new silicon diode will be one of them. I've read a great article on the change out.

https://antiqueradios.com/forums/viewtopic.php?f=6&t=347982

Thanks for some great education, more questions later.

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 Post subject: Re: selenium rectifier and shock hazard
PostPosted: Jan Thu 24, 2019 10:13 pm 
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Chris108 wrote:
Just measure the B+ voltage under the line input and operating conditions in the service literature. If the DC is within 10% of normal, the selenium is fine and can be left alone.


might i add, allow the set to be on for a while before measuring the B+. that could be 5 minutes or 55 minutes.

i've seen a few seleniums work well at start-up, but after being on for a while, they lost 10-50 volts.

steve

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 Post subject: Re: selenium rectifier and shock hazard
PostPosted: Jan Fri 25, 2019 2:09 am 
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Thanks I'm upgrading the selenium rectifier. :mrgreen:

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 Post subject: Re: selenium rectifier and shock hazard
PostPosted: Jan Fri 25, 2019 2:51 am 
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Good Luck
Attachment:
can_of_worms.jpg
can_of_worms.jpg [ 81.49 KiB | Viewed 1130 times ]


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 Post subject: Re: selenium rectifier and shock hazard
PostPosted: Jan Fri 25, 2019 2:58 am 
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Whats with the can of worms, are you saying this will not work by upgrading to a silicon diode? Other G500 radios have the upgrades, no issues, its just a tool for my survival gear, the vintage value is zero since I've rebuilt it from scratch..

As I said this is my daily radio, a radio I need to be working 100%, not a fire hazard, and not a museum radio like my other dozen around my home.

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 Post subject: Re: selenium rectifier and shock hazard
PostPosted: Jan Fri 25, 2019 4:44 am 
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Maybe someone can help me with another issue.

I'm looking at a resistor or capacitor on the osc. coil it is unique as its brown like a turd, and the two ends that solder into the chassis have a wire wrapping around each wire from the factory. The brown turd looks like a wax exterior without markings.

Its soldered to one of the end lugs of the osc. coil, not the middle. The other end is soldered to the 1L6.

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 Post subject: Re: selenium rectifier and shock hazard
PostPosted: Jan Fri 25, 2019 5:00 am 
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A picture is worth...

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 Post subject: Re: selenium rectifier and shock hazard
PostPosted: Jan Fri 25, 2019 5:19 am 
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fifties wrote:
A picture is worth...

Every time I try and post photos they are to large.

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 Post subject: Re: selenium rectifier and shock hazard
PostPosted: Jan Fri 25, 2019 5:21 am 
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Here
Attachment:
received_279327272745198_kindlephoto-5393234291.jpg
received_279327272745198_kindlephoto-5393234291.jpg [ 61.12 KiB | Viewed 1108 times ]

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Last edited by walz on Jan Fri 25, 2019 5:35 am, edited 1 time in total.

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 Post subject: Re: selenium rectifier and shock hazard
PostPosted: Jan Fri 25, 2019 5:25 am 
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Joined: Sep Thu 23, 2010 6:37 am
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Location: Powell River BC Canada
Could it be L4 and C12 ?

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 Post subject: Re: selenium rectifier and shock hazard
PostPosted: Jan Fri 25, 2019 5:39 am 
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Here's a link for sr replacement for G500

http://elmphotography.com/radios/ReplaceSR.pdf

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 Post subject: Re: selenium rectifier and shock hazard
PostPosted: Jan Fri 25, 2019 5:49 am 
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Ed Morris wrote:
Here's a link for sr replacement for G500

http://elmphotography.com/radios/ReplaceSR.pdf


I have a copy of this. Thanks.

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 Post subject: Re: selenium rectifier and shock hazard
PostPosted: Jan Fri 25, 2019 6:45 am 
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walz wrote:
Maybe someone can help me with another issue.

I'm looking at a resistor or capacitor on the osc. coil it is unique as its brown like a turd, and the two ends that solder into the chassis have a wire wrapping around each wire from the factory. The brown turd looks like a wax exterior without markings.

Its soldered to one of the end lugs of the osc. coil, not the middle. The other end is soldered to the 1L6.

I believe that could be a wax capacitor, with a "coil" wound around it. Look on the print to verify the components connected to the osc coil.

Philco was notorious for doing that, but I don't remember if it was in the osc stage of their sets. The coil was to prevent reception of long wave, IIRC. I'm sure someone more knowledgeable will correct that if it's mistaken, but removing the coil had no effect on reception.

You might swap in a new capacitor sans coil and see if there's any change in reception.

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 Post subject: Re: selenium rectifier and shock hazard
PostPosted: Jan Fri 25, 2019 1:56 pm 
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walz wrote:

Its soldered to one of the end lugs of the osc. coil, not the middle. The other end is soldered to the 1L6.

Which pin? As stated by fifties, we need to find it on the schematic.

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