Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12) x

Thread Closed
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Zenith T724 Selenium rectifier
#1

I am finishing up a Zenith T724 and only need to replace the selenium rectifier.

The schematic is in Beitmens pages 182 and 183. each page is marked at the bottom.

http://www.americanradiohistory.com/Arch...n-1956.pdf

I cant see the info on the schematic but I was thinking that since there is a 22 ohm resistor between the selenium and the negative side of the ecaps that a simple diode would work?

  If I remember correctly, The anode goes to the negative side of the wires on the selenium and the diode goes to the 22 ohm resistor and on to the negative of the ecap.

Am I wrong here? Do I need a second resistor or a larger value?

Thanks for any help...

(at least it isn't a resisence line cord) Icon_lol

Icon_smile


Attached Files Image(s)
   

Times I have been electrocuted in 2021
As of 1/01/2021
AC: 4 DC: 1
Last year: 6
#2

Yes, the anode goes to the (-) side and the cathode (end with the stripe) goes to the + side. 

You will probably need to increase the size of the dropping resistor.  You can measure the B+ voltage and substitute higher values of resistance until it reads what it should (probably between 100 - 200 ohms).  To be safe I'd use a 2 - 5 watt resistor.

John KK4ZLF
Lexington, KY
"illegitimis non carborundum"
#3

Thank you!
Just to be clear:::
The wire connected to the Negative of the Selenium goes to the anode. Then Diode end goes to a 100 ohm or so 2 watt resistor. (Remove the 22ohm resistor and replace with the 2 watt 100 ohm?) Connect one end of the new resistor to the diode and connect the other end of the new resistor to the negative of the electrolytics?

Icon_smile

Times I have been electrocuted in 2021
As of 1/01/2021
AC: 4 DC: 1
Last year: 6
#4

Yes, you have it correct.  Just guessing on the wattage of the resistor....you might want to use a 5 watter to be safe if you have one.

If you need any diodes I can send a few 1N4007's in the mail tomorrow.  Good luck!

John KK4ZLF
Lexington, KY
"illegitimis non carborundum"
#5

All figured out...
I could not figure it out... it works when I hook up the selenium but I disconnect it and hook up the resistor and diode and it was dead... I FINALLY figured out that it was a 47K resistor at 5 watts... Not a 47 ohm 5 watt... UGH, Icon_lol

Thank you for the offer but I have many diodes.. And now I have lots of 47K 5 watt resistors... Icon_rolleyes

Icon_smile

Times I have been electrocuted in 2021
As of 1/01/2021
AC: 4 DC: 1
Last year: 6




Users browsing this thread:
[-]
Recent Posts
Philco 42-345 Restoration/Repair
Thank you MrFix55 and GarySP with helping with the Antenna, for now I am placing the Antenna on the back burner and work...osanders0311 — 02:24 PM
The list of my radio & TV collection!
Yes, Michael. But strangely enough, I managed to keep the original veneer. I must admit that I don't really like it, so ...RadioSvit — 02:21 PM
The list of my radio & TV collection!
Good radio. I bet there was a lot of veneer fixing.morzh — 02:16 PM
Philco 46-480 Electronic Restoration
>> it is because I am retired and a little demented. You have just the right amount of it. No perfectly sane p...morzh — 02:14 PM
The list of my radio & TV collection!
Old Zenith 5S-29 tube radio. First turn-on after repair and reception quality testing. Demonstration of the operation of...RadioSvit — 01:27 PM
Philco 42-345 Restoration/Repair
Welcome to the Phorum, osanders0311!  Regardless how far you intend to restore this set, first priority should be replac...GarySP — 11:51 AM
Philco 46-480 Electronic Restoration
Joseph, it is because I am retired and a little demented. My problem is that I wanted to own a collection that spans th...MrFixr55 — 11:29 AM
Philco 46-480 Electronic Restoration
Wow, here I am with only two restored radios. I’ve got to boost those numbers! If you can’t run with the big dogs, you m...jrblasde — 10:04 AM
Philco 46-480 Electronic Restoration
Hello MrFixr55, That will for sure keep you out of trouble! Last Sunday was spent mostly doing yard work anyway the we...radiorich — 09:50 AM
Philco 46-480 Electronic Restoration
Throw in all the Audio equipment that has to be kept in a bedroom (my office)L. 8 portable self contained PA speakers, ...MrFixr55 — 07:40 AM

[-]
Who's Online
There are currently 1171 online users. [Complete List]
» 3 Member(s) | 1168 Guest(s)
AvatarAvatarAvatar

>