05-14-2009, 06:54 AM
Hello and welcome.
There are two factors contributing to the higher voltages you are seeing.
One is the fact that today's line voltage is higher than it was in early 1940 when your 40-201 was built. Back then, 110 to 115 volts was the norm; today, it runs between 122 and 128 (125 on average).
The other factor is the types of meters used back then compared to now. Back in the day, voltmeters with a sensitivity of 1000 ohms per volt were used. These tended to load down the circuit being tested, and as a result gave readings which were actually a bit lower than what the actual voltage was.
Now, with today's modern high-impedance digital multimeters, very little load is placed on the circuit under test when voltage measurements are taken, resulting in a far more accurate reading.
The higher line voltage of today makes the voltages inside the set higher than they were in 1940. And you are measuring them accurately with your modern multimeter - unless you are using 1930s vintage test equipment.
Do not worry about the electrolytics you have used - as long as you have installed them with the proper polarity (positive to B+, negative to B-), and they have a working voltage higher than the voltage being applied to them, they will be fine.
A quick look at the voltages you have posted indicates a problem in the output stage, since your plate voltages are low on your output tubes. Check your audio output transformer - these are notorious for going bad in 1939-1942 Philcos. Check resistors in the audio output circuit to make sure they have not drifted more than 20% off posted values. Test the tubes.
And finally, you did replace ALL of the paper and electrolytic capacitors, right?
Good luck - the 40-201 is an excellent radio when properly restored, with plenty of volume and tone. Very sensitive too with its built-in loop.
There are two factors contributing to the higher voltages you are seeing.
One is the fact that today's line voltage is higher than it was in early 1940 when your 40-201 was built. Back then, 110 to 115 volts was the norm; today, it runs between 122 and 128 (125 on average).
The other factor is the types of meters used back then compared to now. Back in the day, voltmeters with a sensitivity of 1000 ohms per volt were used. These tended to load down the circuit being tested, and as a result gave readings which were actually a bit lower than what the actual voltage was.
Now, with today's modern high-impedance digital multimeters, very little load is placed on the circuit under test when voltage measurements are taken, resulting in a far more accurate reading.
The higher line voltage of today makes the voltages inside the set higher than they were in 1940. And you are measuring them accurately with your modern multimeter - unless you are using 1930s vintage test equipment.
Do not worry about the electrolytics you have used - as long as you have installed them with the proper polarity (positive to B+, negative to B-), and they have a working voltage higher than the voltage being applied to them, they will be fine.
A quick look at the voltages you have posted indicates a problem in the output stage, since your plate voltages are low on your output tubes. Check your audio output transformer - these are notorious for going bad in 1939-1942 Philcos. Check resistors in the audio output circuit to make sure they have not drifted more than 20% off posted values. Test the tubes.
And finally, you did replace ALL of the paper and electrolytic capacitors, right?
Good luck - the 40-201 is an excellent radio when properly restored, with plenty of volume and tone. Very sensitive too with its built-in loop.
--
Ron Ramirez
Ferdinand IN
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