PHILCO PHORUM

ERROR in Model 90 Service Info (using one Type 47 output tube)

For decades, the Philco service information for the "mid" production Model 90 using a single Type 47 output tube has contained a serious error, which can be very confusing to anyone attempting to restore this particular set.

In the official Philco Service Bulletin No. 85, AND in John F. Rider's Perpetual Troubleshooting Manual, Volume II, Philco pages 2-26 to 2-29, it shows two metal can multi-capacitor packs - one containing four capacitors, the other containing two. The error is not only in the schematic, but also in the parts list and Table 4 - Condenser Data.

Look at the partial erroneous schematic below:

Actually, each metal can contains THREE capacitors.

In addition, in Bulletin 85, and in Rider's Volume II, Philco page 2-27, Table 4 - Condenser Data gives incorrect values for parts (24) and (30). The table below shows the errors, and gives the correct data:

The parts list (back page of Bulletin 85, or Rider's Volume II, Philco page 2-29) gives the correct part numbers - but the WRONG data for each!

The diagrams below identify the parts in question, and show the true contents of each.

The drawings above are actually in Rider's Volume II, Philco page 2-25. Interesting how the mistake was never caught by Philco or Rider.

Notice above how one end of each of the capacitors connects to the metal can, which in turn is connected to the chassis (ground) by two bolts.

Remember, one of the cans will have a black wire, a white wire, and a green wire coming out of it. This is capacitor (30). Capacitor (24) has three black wires, and contains three 0.25 uF capacitors. (0.25 uF may be replaced by 0.22 uF, 630 WVDC.)

The schematic for this model was corrected by me before I posted it here quite some time ago, and shows the erroneous extra Part (24) as being actually part of can (30).