Currently working on a Philco 42-350 (http://www.nostalgiaair.org/PagesByModel/523/M0013523.pdf)

Part number 78 is a 270 ohm resistor that has half vaporized in this set. The schematic and parts list do not list the wattage for this resistor but it is large in physical size. Since the markings are decimated as well, how can I determine the proper wattage of this resistor. It is in line with the center tap of the power transaformer on the schematic so I am assuming it is at least 1 watt but looks to be biiger than even the 1 watts I have seen in these old sets...

If its not screwed to the chassis, my bet would be a 3 watt.
Greg

:Currently working on a Philco 42-350 (http://www.nostalgiaair.org/PagesByModel/523/M0013523.pdf)
:
:Part number 78 is a 270 ohm resistor that has half vaporized in this set. The schematic and parts list do not list the wattage for this resistor but it is large in physical size. Since the markings are decimated as well, how can I determine the proper wattage of this resistor. It is in line with the center tap of the power transaformer on the schematic so I am assuming it is at least 1 watt but looks to be biiger than even the 1 watts I have seen in these old sets...

Go to this site:

http://www.philcorepairbench.com/

There's a resistor size area for Philco radios. Old resistors were larger in size but wattage not as one knows modern resistors. Probably two watt?

Bill VA

:Currently working on a Philco 42-350 (http://www.nostalgiaair.org/PagesByModel/523/M0013523.pdf)
:
:Part number 78 is a 270 ohm resistor that has half vaporized in this set. The schematic and parts list do not list the wattage for this resistor but it is large in physical size. Since the markings are decimated as well, how can I determine the proper wattage of this resistor. It is in line with the center tap of the power transaformer on the schematic so I am assuming it is at least 1 watt but looks to be biiger than even the 1 watts I have seen in these old sets...

After you take your best shot at the resistor's wattage and get your set playing, measure the voltage across it. Calculate power dissipation, I^2R, and make sure that the resistor's rating is at least double the actual power.

I'm thinking that leaking filter caps, particularly Cap 40A, might have blown that resistor #78 to smithereens. If that theory is correct, the resistor's blowing up might have saved the speaker field coil. Is the field coil OK?

:Currently working on a Philco 42-350 (http://www.nostalgiaair.org/PagesByModel/523/M0013523.pdf)
:
:Part number 78 is a 270 ohm resistor that has half vaporized in this set. The schematic and parts list do not list the wattage for this resistor but it is large in physical size. Since the markings are decimated as well, how can I determine the proper wattage of this resistor. It is in line with the center tap of the power transaformer on the schematic so I am assuming it is at least 1 watt but looks to be biiger than even the 1 watts I have seen in these old sets...

If the resistor did save the field coil, then maybe it would be best to replace it with one that will just handle the current without overheating? ...Or, a better route would be to beef up the resistor so that it doesn't drift from overheating. Then insert a fuse.

T.

:If the resistor did save the field coil, then maybe it would be best to replace it with one that will just handle the current without overheating? ...Or, a better route would be to beef up the resistor so that it doesn't drift from overheating. Then insert a fuse.
:
:T.

I have not had a chance to do much testing at this point. I found the blown resistor during my visual inspection of the components I always perform. I need to do a parts order so I want to include that one in my order.

the Philco Repair Bench site did not list the 270 ohm resistor but looking at some picturs on there my best educated guess is that this may be a 2 watt.

If this is true that it is a 2 watt, any suggestions on what I should go with? Ceramic, carbon etc??

The "type" of resistor won't make a difference in this ckt; what's cheapest or what do you have available? I'm looking at the RadioDaze catalog: you can get five 2-W metal oxide caps for $0.85. Or, you can get one 5-W power resistor for $0.37.

:
:I have not had a chance to do much testing at this
:If this is true that it is a 2 watt, any suggestions on what I should go with? Ceramic, carbon etc??

Here is a picture of the resistor I am trying to identify:

http://www.harwintonphoto.com/resistor.jpg

I know the value from the schematic (270 ohm) I just can't figure out the wattage and it is not listed on the schematic. It is a wire wound because the wire is sticking out of it and it is 1-1/4 inches long and a 1/4 inch diameter.

Anyone want to guess at the wattage for me.

I still say its 3 watts, put a 5 watt in to be sure and then if your still not sure measure the voltage drop and do some ohms law to calculate the power.
Greg

:Here is a picture of the resistor I am trying to identify:
:
:http://www.harwintonphoto.com/resistor.jpg
:
:I know the value from the schematic (270 ohm) I just can't figure out the wattage and it is not listed on the schematic. It is a wire wound because the wire is sticking out of it and it is 1-1/4 inches long and a 1/4 inch diameter.
:
:Anyone want to guess at the wattage for me.

Before, I thought 2 watt. But if the p/n is 33-127431 it's one watt.

Bill VA

:Here is a picture of the resistor I am trying to identify:
:
:http://www.harwintonphoto.com/resistor.jpg
:
:I know the value from the schematic (270 ohm) I just can't figure out the wattage and it is not listed on the schematic. It is a wire wound because the wire is sticking out of it and it is 1-1/4 inches long and a 1/4 inch diameter.
:
:Anyone want to guess at the wattage for me.

Hi

All the current for you radio goes through this resistor. If current is 50 ma the resistor dissipates around 2/3 watt. Even though less than 1 watt I would use 2 watt or greater.

Before operating the radio replace filter caps. A shorted filter cap may have caused this resistor to burn?

Norm

:Before, I thought 2 watt. But if the p/n is 33-127431 it's one watt.
:
:Bill VA
:
::Here is a picture of the resistor I am trying to identify:
::
::http://www.harwintonphoto.com/resistor.jpg
::
::I know the value from the schematic (270 ohm) I just can't figure out the wattage and it is not listed on the schematic. It is a wire wound because the wire is sticking out of it and it is 1-1/4 inches long and a 1/4 inch diameter.
::
::Anyone want to guess at the wattage for me.