10-04-2005, 06:22 PM
It was inevitable.
I'd read the horror stories about Philco 89 sets, but I had never experienced any of the difficulties.
Until now.
A complete chassis and cabinet restoration of a Philco 89L from 1933-34 was in order. The cabinet refinish went well, and it awaits its finished chassis (photos forthcoming when I finish this roll of film).
The chassis was quite another matter. It's standard operating procedure for me to not only replace all of the paper and electrolytic caps and out-of-tolerance resistors, but also to go ahead and rewind the primaries of those pesky RF coils; since if they aren't bad already, they will be sooner rather than later.
Having done all that, I fired it up for the first time.
Nothing.
Found the primary of the 2nd IF was open, and replaced it with another.
Now the set would sometimes tune in stations, weakly; but more often than not, it would just squeal.
After spending most of the day tearing out what hair I have left, I suddenly found that sometimes, when I touched the antenna lead to the grid cap of the Type 36 det-osc tube, the set would mysteriously come to life for a little while.
AHA!!! Having read about the trouble with the oscillator circuit in Philco 19 and 89 sets, I had already reduced the Type 36 oscillator cathode resistor from 15K to 10K per a Philco recommendation; but 10K wasn't enough.
What I ended up doing was trying different Type 36 tubes until I found one that would work well in the circuit, and I also had to further reduce the Type 36 cathode resistor to 7,500 ohms. (That suggestion is made in Ghirardi's "Radio Troubleshooters Handbook.")
That did the trick, and now the set comes right on and plays when turned on, without any "finagling" (sp?).
All it needs now is a volume control replacement, and it's good to go and ready to launch.
WHEW!!!
I'd read the horror stories about Philco 89 sets, but I had never experienced any of the difficulties.
Until now.
A complete chassis and cabinet restoration of a Philco 89L from 1933-34 was in order. The cabinet refinish went well, and it awaits its finished chassis (photos forthcoming when I finish this roll of film).
The chassis was quite another matter. It's standard operating procedure for me to not only replace all of the paper and electrolytic caps and out-of-tolerance resistors, but also to go ahead and rewind the primaries of those pesky RF coils; since if they aren't bad already, they will be sooner rather than later.
Having done all that, I fired it up for the first time.
Nothing.
Found the primary of the 2nd IF was open, and replaced it with another.
Now the set would sometimes tune in stations, weakly; but more often than not, it would just squeal.
After spending most of the day tearing out what hair I have left, I suddenly found that sometimes, when I touched the antenna lead to the grid cap of the Type 36 det-osc tube, the set would mysteriously come to life for a little while.
AHA!!! Having read about the trouble with the oscillator circuit in Philco 19 and 89 sets, I had already reduced the Type 36 oscillator cathode resistor from 15K to 10K per a Philco recommendation; but 10K wasn't enough.
What I ended up doing was trying different Type 36 tubes until I found one that would work well in the circuit, and I also had to further reduce the Type 36 cathode resistor to 7,500 ohms. (That suggestion is made in Ghirardi's "Radio Troubleshooters Handbook.")
That did the trick, and now the set comes right on and plays when turned on, without any "finagling" (sp?).
All it needs now is a volume control replacement, and it's good to go and ready to launch.
WHEW!!!
--
Ron Ramirez
Ferdinand IN
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