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

philco 42-360 power transformer
#1

I have a Philco 42-360 that needs a new power transformer. The schematic shows 320 vdc on the output of the rectifier 84. I`m not sure what the current requirements are needed to operate this radio.
#2

Welcome to the Phorum!
Icon_wave

Can't answer your question but someone surely will be able to help. The service bulletin for the radio is available at http://www.audiophool.com/Philco.html .
#3

Hi and welcome to the Phorum,
Your looking at about 60ma. They're pushing that 84 pretty hard.

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
#4

Well....let's try to do the first order calculation.

The rectified voltage is 320V. The dropout across the field coil's DC resistance of 1.7kOhm is 130V (down to 190V). We're lucky we have the numbers directly before and after.
This makes the total of 130V/1700 Ohm = 75mA.

Now each half-winding will conduct the same average current exactly 1/2 of the period that makes it 38mA average per half-winding.

Add a margin of say 50% (or whatever you are comfy with), this will make it 57mA. I'd say, that is enough.

(Almost radio engineer)

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
#5

PS. Saw Terry's reply. Hey! I was pretty darn close! Icon_lol

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
#6

Hey Mike,
I do the rough calculation by multiplying the # of tube not counting the OP or rectifier X 5 (ma) If and tube has more than 1 section + 5 more ma per, diodes don't count. OP= 20ma. So 7 tubes X 5ma + 20= 55ma + a little for good luck=60ma.
Then I look up the tube specs to see if the rectifier can handle the current load. 84 is good for 60ma.

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
#7

Terry

I'd do the same, but when I'm lucky to have the Voltages directly shown along the current path, with known resistances for the dropouts, I use those - takes the guesswork out of the process.

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
What do I have? Philco 655
Wouldn't be the first "Phranken-Philco" to come out of the factory. Kinda like model year end cars built back...GarySP — 07:45 PM
Philco Model 76 Highboy
That's a nice looking cabinet. With a little bit of rub on stain and paste wax that should even out the finish. When you...Radioroslyn — 05:20 PM
What do I have? Philco 655
Hi Adam, Others may know more than me, but it was not uncommon for Philco to run out of cabinets and use one for a new...MrFixr55 — 02:51 PM
What do I have? Philco 655
Haven't been on here in a while, and it's been a while since I've worked on a Philco.  I picked this up a while back, an...adamrobertg — 08:10 AM
Clear Schematic for 41-255
Hello Ross, We have all been there don't worry the guys here have you taken care of !! Sincerely Richardradiorich — 09:35 PM
Clear Schematic for 41-255
What's really funny is I looked at the pages and saw 255 and it took me 30 sec of looking at the schematic trying to fig...RossH — 05:19 PM
Clear Schematic for 41-255
Ross, sorry, clicked on the wrong one. here's the down load for the 41-255 as an attachment.klondike98 — 04:40 PM
Clear Schematic for 41-255
RossH - Were you looking at our copy of the 1941 Yearbook, or one that you found elsewhere?DaleHCook — 04:12 PM
Clear Schematic for 41-255
Ditto. Perfectly readable here. Monitor or computer problems?!rfeenstra — 12:10 PM
Clear Schematic for 41-255
I have just gone to the link Gary provided in #2, the 1941 yearbook, and I do not see any whatsoever small print that I ...morzh — 12:00 PM

[-]
Who's Online
There are currently no members online.

>