I have a 41-220C and unfortunately my candohm reads are off. I've never worked with a candohm before and I need some help. My goal is to replace this with a terminal strip and wire the replacement resistors in series. I assume the side that will go to chassis ground is on the 53 ohm side which is the plug side. Please let me know if that is incorrect. My real help is needed in my candohm math for wattage. I have the ohm values as one given but when I assume to plug in another given, under my ohm's law equations, I get crazy wattages. I would like to be able to figure these on my own in the future but I'm not that advanced yet to get this. Thanks in advance, Mark
Hi Mark here's the cheap and dirty way to get the heaters working and makes no heat. All you need is a 53 or so ohm 1W resistor and a 1N4007.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
(This post was last modified: 09-03-2018, 07:30 PM by Radioroslyn.)
Candohm blues ??
Sounds like a fish. Don't you Bostonians throw out your nets a catch a wicked mess of 'em??
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Thanks Terry, always good to hear from you. So, you got the lamp's voltage of 6.3v and with the resistance of 53 ohms, got .75 watts rounded to 1 watt...thanks for that. How did you get to figure the diode would do the rest?
Also, I still wire the resistor and diode in series with the ground side the resistor? Just picking your brain.
Paul, after letting the candohm frustrate me I was channeling Muddy Waters.
>How did you get to figure the diode would do the rest?
It's a highly guarded secret but since your a member I'll spill the beans.
So how it works is that the diode doesn't conduct during the negative cycle
of the ac voltage applied to it. It does provide abt a 40v drop or 125vac X .7=88vdc
You need abt 100v so it is slightly low but is within reason. I suppose if it seem too
low you could add a SMALL cap from the 1N4007 cathode to B- and that will boost
the heater voltage. If you want to experiment I'd start with a .01mfd or so. No
big eletrolytics.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
The filament current is 150 ma, so .15 Amps, one section of the candohm is across the pilot lamp, as well as being in series with the tube filaments, the other section is only in series with the tube filaments, no portion of it is connected to the chassis, only to one side of the power line. Don't use the diode, that's for sets with a ballast tube that need to drop lots of volts, this set of tubes needs 95 volts to function correctly. keep the section across the pilot lamp the same as the factor specs, maybe use a larger one for the other section for more voltage drop. Of course an easy way to get rid of an extra 15 volts if to swap the 35A5 for a 50A5, then you only need the section across the pilot lamp.
Regards
Arran
(This post was last modified: 09-04-2018, 08:10 PM by Arran.)
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
