07-03-2023, 03:25 PM
The original Philco service info may be found here, on this very website.
https://philcoradio.com/library/download...20Book.pdf
First of all -
Looking at the alignment instructions, it is suggested that alignment may be performed with an output meter connected across the speaker voice coil.
It is not mandatory that a VTVM be used with an aligning adaptor (and there may no longer be any in existence, and if there is, whoever has some stashed away may not know what they are for).
Use of the VTVM will, however, result in a more precise alignment provided that modern equipment such as a function generator, which does not drift, used with suitable attenuators as needed is also used.
Now comes the mystery of just exactly what an "aligning adaptor" was, and where those light and black wires connected internally in the adaptor.
We can easily ascertain that this adaptor had a loctal base, and a loctal socket on top, with each pin of the base connected to the corresponding socket connection on top. That is to say, pin 1 of the base to pin 1 of the top socket, pin 2 to pin 2, pin 3 to pin 3, etc.
The real mystery lies in where those light and black wires would have connected in the adaptor.
To figure that out, careful study of the schematic is called for.
We know from the scant information given in the alignment instructions, that the VTVM is intended to measure AVC voltage, which is a negative voltage.
Now we need to know which connections this aligning adaptor would have used which would have measurable AVC voltage in common so the adaptor could be used with two tubes with completely different pinouts.
Looking at the 40-140/40-145 schematic, we see that AVC voltage will be present at one of the 7C6 diode plates which is either pins 5 or 6. We also see that AVC voltage will be present on the 1232 control grid, pin 6. To measure AVC voltage with such an adaptor, a provision for a "low" or "ground" connection must also be provided.
On the 40-140/40-145 schematic, the two tube pins which have AVC voltage in common are - pin 6 for AVC high, pin 7 for AVC low or ground.
Therefore, a Philco "aligning adaptor" would have had a loctal base, a loctal socket on top, and wires connected from each pin of the base to the same corresponding pin on the top socket, plus - the "light" wire to pin 6 of the base & socket, and the "black" wire to pin 7 of the base & socket.
See image below.
Without an aligning adaptor, if you want to use a VTVM to measure AVC voltage, you may simply connect the "high" end of your VTVM to pin 6 of the 1232 (under the chassis) and the "low" end of same to pin 7 of the 1232 for IF alignment.
For RF alignment, connect the "high" end of the VTVM to pin 6 of the 7C6, and the "low" to chassis ground.
Or just use an output meter across the speaker voice coil and be done with it.
https://philcoradio.com/library/download...20Book.pdf
First of all -
Looking at the alignment instructions, it is suggested that alignment may be performed with an output meter connected across the speaker voice coil.
It is not mandatory that a VTVM be used with an aligning adaptor (and there may no longer be any in existence, and if there is, whoever has some stashed away may not know what they are for).
Use of the VTVM will, however, result in a more precise alignment provided that modern equipment such as a function generator, which does not drift, used with suitable attenuators as needed is also used.
Now comes the mystery of just exactly what an "aligning adaptor" was, and where those light and black wires connected internally in the adaptor.
We can easily ascertain that this adaptor had a loctal base, and a loctal socket on top, with each pin of the base connected to the corresponding socket connection on top. That is to say, pin 1 of the base to pin 1 of the top socket, pin 2 to pin 2, pin 3 to pin 3, etc.
The real mystery lies in where those light and black wires would have connected in the adaptor.
To figure that out, careful study of the schematic is called for.
We know from the scant information given in the alignment instructions, that the VTVM is intended to measure AVC voltage, which is a negative voltage.
Now we need to know which connections this aligning adaptor would have used which would have measurable AVC voltage in common so the adaptor could be used with two tubes with completely different pinouts.
Looking at the 40-140/40-145 schematic, we see that AVC voltage will be present at one of the 7C6 diode plates which is either pins 5 or 6. We also see that AVC voltage will be present on the 1232 control grid, pin 6. To measure AVC voltage with such an adaptor, a provision for a "low" or "ground" connection must also be provided.
On the 40-140/40-145 schematic, the two tube pins which have AVC voltage in common are - pin 6 for AVC high, pin 7 for AVC low or ground.
Therefore, a Philco "aligning adaptor" would have had a loctal base, a loctal socket on top, and wires connected from each pin of the base to the same corresponding pin on the top socket, plus - the "light" wire to pin 6 of the base & socket, and the "black" wire to pin 7 of the base & socket.
See image below.
Without an aligning adaptor, if you want to use a VTVM to measure AVC voltage, you may simply connect the "high" end of your VTVM to pin 6 of the 1232 (under the chassis) and the "low" end of same to pin 7 of the 1232 for IF alignment.
For RF alignment, connect the "high" end of the VTVM to pin 6 of the 7C6, and the "low" to chassis ground.
Or just use an output meter across the speaker voice coil and be done with it.
--
Ron Ramirez
Ferdinand IN
