I recently had the opportunity to restore a 1929 Philco Model 87 Highboy for a client that found this nice unit from a local seller.
As you can see, the unit is in pretty good shape and certainly worthy of putting in the effort.
Removing the chassis revealing the Model 87’s guts.
First thing’s first, address the power supply before power up! The power supply filter capacitors (as well as a few others) are located in the “condenser block”, a rectangular metal can bolted to the top of the chassis.
During my research on the Model 87, I ran across this excellent post regarding, “Recapping a Philco Model 87 Radio” and used this as a template for this repair.
Note to self: Don’t do this in the garage, even with the garage doors open. You will still smoke up and stink up the house!
While the capacitor bank schematic checked out, I decided to use film capacitors instead of electrolytic caps as the film caps should last longer.
…and the filament supply.
The coupling capacitors and plate resistors between the RF sections are found in these cylinders and sealed with tar. I melted the tar out of one to verify and found the expected capacitor guts. Interestingly, the 250Ω resistor was a length of enameled wire, hand wrapped back and forth multiple times and stuffed into the cylinder.
These were replaced with modern equivalents.
The rest of the set checked out fine. All RF transformers tested good, nothing open, and all remaining resistors were within spec. I checked all the transformers for resistance (a minimal check at least) and of course, Deoxit on all contacts, switches, pots, etc.
I brought the unit up slowly using a variac and found only one tube, a #26 with an open filament. I replaced this tube with a NOS #26 and the radio fired right up! I gave it a quick final tune up and she sings once again!