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

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

71b, please help with checking coils
#6

The link I posted above from Nostalgia air has both a voltage reading chart, tube pinout diagram and schematic. The chart shows voltages measured with the negative of the voltmeter to the cathode of the tube, but you will get close enough readings with the negative to chassis. The cathode to filament voltage column measures the voltage across the bias resistor for the output tube (15 to 20 V), so not really significant for the RF section.

It is most important to measure the plate and screen grid voltages of the RF, det/osc and IF tubes. Should be around 200V-250V on the plates and around 90V on the screens. If you don't have close to these voltages, you will get poor or no reception.

Here is the link to the info again:

http://www.nostalgiaair.org/PagesByModel...013837.pdf


Messages In This Thread
RE: 71b, please help with checking coils - by Mondial - 05-04-2013, 04:38 PM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
An attempt to remove the Field Coil from a G speaker
Gary I in fact did, on a 38-14, I think, where I had a speaker with the dead coil. Well...it kinda worked. Kinda, be...morzh — 10:38 PM
An attempt to remove the Field Coil from a G speaker
Mike, what ever happened to that plan you had to try using a rare earth magnet to magnetize the pole? This looks like a...GarySP — 10:25 PM
RCA T62 is playing.....
Beautiful set.morzh — 09:07 PM
An attempt to remove the Field Coil from a G speaker
Well....here it is. The green stuff. Unfortunately, probably penetrates deep. I opened the top layer and saw that: ...morzh — 08:58 PM
Philco 91 Restore Code ??
:clap: :clap: :clap: :clap: Really nice workmanship!!! Top of the chassis looks great. Sorry about the long winded e...MrFixr55 — 08:09 PM
Philco 40-120C Restoration
Thank you for your reply. I will check voltages on the other tubes, look at resistor 23 and cap 25, etc. If all else fai...bluecap — 07:58 PM
RCA T62 is playing.....
Nice looking set great save. DavidDavid — 07:48 PM
Philco 89 indicator light.
Hello Jim, I have done several 89s. The trick is to move the drum in or out on it's shaft. You will need to loosen a set...dconant — 07:36 PM
An attempt to remove the Field Coil from a G speaker
MrFixr Yes, it is my plan to go with 45rpm spider if I go that far. No, the pole was not left-handed as I unscrewed ...morzh — 07:14 PM
Philco 40-120C Restoration
Change the tube. Check the tube's bias network. Are any other tubes experience the drop or just this?` Is resistor 23 OK...morzh — 07:09 PM

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

>