Philco 38-690 Troubleshooting. - Printable Version

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Philco 38-690 Troubleshooting. - NV3G - 01-15-2019

I am working on a Philco 38-690.

Can I test and troubleshoot the power / audio chassis WITHOUT connecting RF chassis to it?

Thank you,
nv3g
Oscar

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RE: Philco 38-690 Troubleshooting. - tbone - 01-15-2019

http://www.nostalgiaair.org/pagesbymodel/255/M0013255.pdf

If you look at the circuits in this radio, both power supplies are needed for the audio amp. The bottom one supplies the current for the driver and finals, and the top one supplies grid bias to the amp and B+ to the receiver. So you’ll need both power supplies running and all speakers hooked up to start with.

I don’t know what the bias voltages would be like with the top power supply not properly loaded. I suspect not correct. If that question could be answered by someone how did exactly what you want to try, we’ll know if anything will get damaged.

I get that it would keep the bench less cluttered while working on it. Other than that, not sure what would be gained.

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