Philco 37-650 restoration - Printable Version

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+--- Thread: Philco 37-650 restoration (/showthread.php?tid=22415)

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Philco 37-650 restoration - vpa39 - 04-20-2021

Greetings, it's been awhile since my last restoration...
I am about to start a restoration of the 37-650 console, and I am trying to set up my material order list. I know I have to get to the hidden components under the RF sub-section which I will do first.. But, I need to order the components ASAP. First question I have of probably many to go and forgive my inexperience with this radio. The chassis houses a power resistor strip. It looks like 19 ohms and 119 ohms although the schematic is blurry. I want to replace that strip because the ohms were not stable and out of tolerance. I will go with a 20 and a 120 ohm resistor. My problem is I couldn't figure out the wattage of those resistors. I could go with 25 watts and call it quits, but that's not what I want to do.

Thank you for any help,

Vin

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RE: Philco 37-650 restoration - morzh - 04-20-2021

I think the actual dissipation of the 109 Ohm one is about 1W and the 19 Ohm - 0.2W.
So if you go with 5W and 1W respectively, you should be fine.

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RE: Philco 37-650 restoration - vpa39 - 04-20-2021

Thank you kindly, I just could not figure it out.

Vin

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RE: Philco 37-650 restoration - morzh - 04-21-2021

Well,

I assumed that the total current should be around 100mA.

Both resistors in series conduct the total current.

100mA on a 109 ohm creates 1.1W dissip; and the 19 Ohm is roughly 1/5th of it which is 0.2W.
I use a factor of 5x to size up resistors. So it becomes 5W and 1W.

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RE: Philco 37-650 restoration - vpa39 - 04-21-2021

Awesome! Thank you very much for the time and explanation.

Vin

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