[Guest]

Hi:

Am working on a Philco 60. I removed the 80 Rect. to check the AC voltage to the filament and plates. Filament checked out OK at 5.6 volts
but the plates voltage which should be arounf 680 volts came in at 785volts. I did this reading with the volt meter probes clipped on the 2 and 3 pin. Is this transformer OK to use??
Thanks!!

[rickd]

What kind of meter did you use? Newer meters don't load the circuit like the older ones did so they give a higher reading. Also todays line voltages sometimes run a little higher. What is your line voltage? Although it does sound a little high, it's probably ok.

[Texasrocker]

I always use this rule for checking high-voltages on the rectifier sockets that have a AC Tranformer on chassis. #1 , BE CAREFUL in getting your voltage measurements!! #2, measure across both pins of high voltage and write down the total hi-volts measurement. Then, carefully check each side of the 2 hi voltage tube socket-pins (one at a time) with negative test probe to chassis ground with meter. Each separate Hi Voltage reading from chassis ground from each the separate "plates" of the rectifier should read the same back to chassis ground, and add up to the total of the 1st reading directly across the plate-pinouts! Then, consult your RCA tube manual and read specs of the #80 tube, to see if voltages are within specs. Everyone involved in servicing vintage radios needs a "tube manual" for tube info on their workbenches indeed!! Randal

[Guest]

Hi rickd:

It is a newer type digital meter. MY house voltage is about 117 volts.
I placed a 1 amp fuse so tthis might help it a little in case things get too high in voltage.

Thanks
John

[Guest]

Hi TexasRocker:

I did take a reading with the 80 Rect. out of the set and placed the meter probes across the two plate pins There I got a high reading of 786 volts AC. which to me looked high and promted me to post this question.
However I did not do the seperate reading of each plates with the negative probe ground to chassie. I will try this.
I am a little confused once I get these 2 plate readings. Can you explain again from this point?
PS I do have a tube booklet with tube info and diagrams.

Thanks
John

[Ron Ramirez]

Bear in mind that with the 80 tube out of the socket, the voltage you are measuring is a no-load voltage; that is, nothing is connected to the high voltage winding with the 80 tube out of the socket, so the reading will be higher. With the 80 IN the socket (assuming the rest of the tubes are also in their sockets and the set is operational), you will find the voltage reading to then be closer to normal.

This is true of any power transformer. With no load, the voltages will be higher than when they are under load.

Incidentally, you are lucky if your line voltage is only 117 volts. A lot of modern homes have anywhere between 120 and 128 volts. 117 will be kinder to your vintage radios.

[Texasrocker]

Hello John, I personally think your AC transformer is right in the ballpark "perfect AC voltages" to your rectifier tube in the high-voltage ratings you described in your previous posts since your checking voltages with tubes removed. Seems you are getting 393 volts to pin #2, and 393 volts to pin #3 plate connections which equal 786 volts reading directly across both pins. Separate readings from each pin#3 #4 to chassis ground should read 393 volts each to chassis ground thru your volt meter.Sounds about correct voltages to me since your all your tubes are out of chassis during your tests. Just trying to clarify my previous post. Ron made a GREAT point also!! Your lucky to have only 117 volts AC coming into your home these days! At my location, I have modern-day AC voltages of 122-125 volts constantly into my home and workbenches! That said, I use a "variacs" w/ AC voltage meter aboard to "monitor", and bring up AC power slowly to power up many of my 1920s, early 30s vintage radios, and never let the modern AC line voltage exceed 110 volts as many,many, of my finest vintage radios would not like todays modern AC voltages supplied to my premises locally!!Randal