Replacing Selenium Rectifiers in Tube Portable Radios
Replacing Selenium Rectifiers in Tube Portable Radios
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I looked up the …
I looked up the diagram on Nostalgia Air and when the battery is used the AC is out of the circuit. As long as you use the right DC battery voltages you can test the radio with batteries. If you have more questions please email me. Good luck!
Rick, can you test …
Rick, can you test that radio with DC voltage by chance? I have a 600 T/O, no battery yet, but I was thinking of making one, thanks.
The radio should …
The radio should play great!
Perfect Rick, your …
Perfect Rick, your the man!
I check voltage on the radio I bought with the selenium bypassed with a 1N4004. Some one else did it, with out a drop down resistor.
The Spec voltage past the rectifier and stock 22ohm R is 128V. I was at about 144V (+16V). The Plate was 119V, +9V (spec 110v). Measuring voltage drop across stock 22ohm R, some basic ohms law math, the ideal resistor is about 100ohm! Don’t have room for 10W in stock location, which is only 1W. I’ll go 3-5W.
I just find the …
I just find the wiring diagram and I would alligator clip in a 150ohm in place of the 22ohm and check plat voltages and performance. If the voltage is low then I would try a 100ohm. Good luck.
The selenium …
The selenium rectifiers I have replaced have had and internal resistance of 100-150 ohms. So I would remove the 22ohm and replace it with a 150ohm 10watt(if you have room) and then check all the plate voltages and the radios performance.
PS the most …
PS the most critical tube is the audio driver a 35C5 which the specs say has
Tung-Sol specs
Max plate voltage 150V
Max grid #2 voltage 130V
For the same 35C5 tube GE specs
Max plate voltage 135V
Max screen voltage 117V
Since line voltage is 117 I should be OK with the existing stock 22 ohm (1W) resistor down from the rectifier. Again the filament heaters are all AC.
Rich I am …
Rich I am overhauling a Zenith Y832. The filament heaters are all AC and by pass the the selenium rectifier (diode).
The current in-line resistor is 22ohm 1W. I am about to order all my new CAPS and wounder do I really need to put in a drop down resistor.
The plates are rated for 100-250 volts. I don’t think the difference will be that great. What do you think. I would rather replace the existing 22ohm with a larger one than add an additional one. Comment appreciated.
And it is cheep too …
And it is cheep too. I hope you enjoy the vids, and ask your questions.
Thank you. I …
Thank you. I appreciate your help. I feel dumb. I see its a half wave rectification. It is just so crude (ha ha) it’s throwing me. In tube audio amps I built, I used a power transformer and regulated DC power for the filaments. I see they made some compromises to make the radio AC/DC powered with out a transformer.
I look forward to watching all your videos. I am sending you PM!
I know it is …
I know it is confusing. I did a video called “Rectifiers, a few basics” 9 months also.
I am confused? How …
I am confused? How can your replace a RECTIFIER with a single diode (plus drop down resistor)?
I thought a rectifier is 4 diodes and a rectifies AC wave form to DC. (I know I am confused). Any one? Please straighten me out. I assume that the filaments are still AC and the diode just clips part of the wave? Totally lost. Thanks
It is surprising …
It is surprising how useful an isolation transformer and a variac are. I use them all the time. It makes a lot of difficult decisions easer and more accurate. It also makes the work safer for the user and there is much less chance of doing damage to the unit under test. Thanks.
Thanks. It is also …
Thanks. It is also very accurate.
Thank you, thank …
Thank you, thank you. This technique makes it so much easier than the way I was doing it. Now I’ve got to apply it to a couple of my GE Convertibles…
Rick, As you had …
Rick, As you had emailed me last week. I will use this variac technique to help determine the resistance needed to suppliment the replacement electrodynamic speaker’s field coil being700 ohms less DC resistance than the original schematic calls for. It’s a simple yet powerful method! Thanks!
Yep, need a …
Yep, need a substitute for the internal impedance of the tube. Thanks.
Replacing tube …
Replacing tube rectifier with a diode can also be done. it is however real important to have a resistor
Thanks. There are/ …
Thanks. There are/were many manufactures of selenium rectifiers of all types. So that and how it is used varies greatly. If your radio is not a tube portable, the procedure is the same except you would check the plate voltage of the audio output tube. I decided to us a tube portable because they are the most critical and if done wrong you will burn out some filaments.
I’ve only had to do …
I’ve only had to do one set with the selenium rectifier (a zenith AM/FM tabletop) and was just told to use a 50 Ohm 10 W resistor. I knew there was a proper way to do it, thanks a bunch!
Hey John,
If your …
Hey John,
If your radio is not a tube portable you just do the same thing but instead of the filament you check the plate voltage of the audio output tube.
It has been a few years since I have been to Vegas, they’ll probably let me in.
Regards,
Rick
Thanks. If it does …
Thanks. If it does go bad, depending on how, it can smell like rotten eggs.
Rick the …
Rick the clairvoyant,
Don’t know how you do it, but once again your timing is perfect. I just finished reading about selenium rectifiers and will soon be replacing one in the wife’s AM/FM. Figuring out how to determine the resistor value had me a bit stymied. But not any longer.
I’ll bet tomorrow something else will pop up that I need to know about. and in a few days you’ll post a vid with the answers. Maybe I should take you to Vegas.
Regards,
John.
great info. i …
great info. i didn’t know those rectifiers could go bad. I hear they smell something awful if they ever burn out.
I hope it helps! …
I hope it helps! Thanks.