04-08-2018, 04:11 PM
http://www.nostalgiaair.org/pagesbymodel...013581.pdf
I am working on a Philco 44B cathedral. Several parts do not match the schematic in Riders. I looked through several Riders volumes (Philco sections) looking for changes pages, as well as searching the internet and the Phorum - but none were found.
For example, the filter choke (part 70) measures 562 ohms. Riders and Radiomuseum says 1750 ohms. I always assumed that such parts are either open or good, and do not change value. Another example: voltage divider 58. Riders says 32 and 235 ohms. Mine measure 24.4 and 257.5 and the values are stable when the terminals are moved. The 24.4 section is -23.75% (the other section is in tolerance). Again, I assumed that wire wound resistors do not normally change values, which is why they were used vs. carbon.
There are 4 flexible wire wound resistors used. One is bad. But the other three do not match the schematic. Part 23 (200 ohms) measures 272.3 ohms. Part 37 (300 ohms) measures 417 ohms. Part 27 (300 ohms) measures 386 ohms. All of these values are stable when the resistor is moved around. I have not removed the sleeves to see how they are actually marked, since unsoldering one end and removing the sleeve would likely destroy the fragile resistor.
Could all of these differences simply be changes, or failure modes I do not understand?
I am working on a Philco 44B cathedral. Several parts do not match the schematic in Riders. I looked through several Riders volumes (Philco sections) looking for changes pages, as well as searching the internet and the Phorum - but none were found.
For example, the filter choke (part 70) measures 562 ohms. Riders and Radiomuseum says 1750 ohms. I always assumed that such parts are either open or good, and do not change value. Another example: voltage divider 58. Riders says 32 and 235 ohms. Mine measure 24.4 and 257.5 and the values are stable when the terminals are moved. The 24.4 section is -23.75% (the other section is in tolerance). Again, I assumed that wire wound resistors do not normally change values, which is why they were used vs. carbon.
There are 4 flexible wire wound resistors used. One is bad. But the other three do not match the schematic. Part 23 (200 ohms) measures 272.3 ohms. Part 37 (300 ohms) measures 417 ohms. Part 27 (300 ohms) measures 386 ohms. All of these values are stable when the resistor is moved around. I have not removed the sleeves to see how they are actually marked, since unsoldering one end and removing the sleeve would likely destroy the fragile resistor.
Could all of these differences simply be changes, or failure modes I do not understand?
