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Philco 38-3 Grounding/antenna issue
#11

Quote:In the meantime will I be able to operate the radio in the current configuration or is there the potential to damage components with the radio in its current state? I have not done any component replacement besides the light bulbs.
No, as it stands the radio, though may work, is not in a robust condition to use.

The primary issue is with the power supply electrolytic capacitors, those large round metal cans or paper covered sleeves with "+" & "-" lead markings (mostly).

Find them and identify from the schematic v.s. the radio. Note how the OEM installation is made. An error when installing replacements can cause severe damage. Replacement may not fit in same location, some technicians prefer to install replacements inside the old, others, disconnect the old completely and install under the chassis, still others leave the old in place on top of chassis and replacement under.

Further restoration will include replacing all other paper type caps that may be in Bakelite housings. The best method is to removed the "innards" and install new caps inside housing, thus preserving the wiring patterns. It is not a good idea to re-route any wiring but do replace wires with rotted insulation in the same path.

There are many other "gotchas". Wherein you have a working radio that means certain irreplaceable (very difficult) components are good, others are weak.

There is one principle when restoring a radio that is helpful. Replace two components at a time and then test. If a failure occurs then it was one or the other component (installation) that has failed. Beware of solder blobs and wire snips too.
"shotgunning" the radio, meaning replacing all caps and some if not all resistors all at once, no in between testing, is very risky if the radio is not familiar to the technician.

Do NOT tinker in the RF/OSC circuits unless proven defective. The mica type caps in general do not fail, do not twist them to verify, disturbing the wiring in that area can make the radio fail by altering wire positions.

GL

Chas

Pliny the younger
“nihil novum nihil varium nihil quod non semel spectasse sufficiat”


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RE: Philco 38-3 Grounding/antenna issue - by Chas - 10-28-2023, 10:47 AM



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