I've restored two Philco Model 90s with the single type 47 output tube and now I'm working on one with push pull type 45 output tubes. The former have three-wire speakers with a four pin connector; one pin is not used. The earlier model with the 45s has a four-wire speaker and I have no continuity in one of the speaker pins (not the same pin not used with the later type 47 model 90s). Do I have a problem or is this normal? Since the open pin on my four-wire speaker is not the same open pin on my three-wire speakers, I don't want to simply test my four-wire speaker by plugging it into one of my restored model 90s having the three-wire speakers.

:I've restored two Philco Model 90s with the single type 47 output tube and now I'm working on one with push pull type 45 output tubes. The former have three-wire speakers with a four pin connector; one pin is not used. The earlier model with the 45s has a four-wire speaker and I have no continuity in one of the speaker pins (not the same pin not used with the later type 47 model 90s). Do I have a problem or is this normal? Since the open pin on my four-wire speaker is not the same open pin on my three-wire speakers, I don't want to simply test my four-wire speaker by plugging it into one of my restored model 90s having the three-wire speakers.
:
Steve

::I've restored two Philco Model 90s with the single type 47 output tube and now I'm working on one with push pull type 45 output tubes. The former have three-wire speakers with a four pin connector; one pin is not used. The earlier model with the 45s has a four-wire speaker and I have no continuity in one of the speaker pins (not the same pin not used with the later type 47 model 90s). Do I have a problem or is this normal? Since the open pin on my four-wire speaker is not the same open pin on my three-wire speakers, I don't want to simply test my four-wire speaker by plugging it into one of my restored model 90s having the three-wire speakers.
::
:
:Lou, There should be continuity between all pins. Hold the plug with pins facing you, start with the small pin. It is conected to one end of the transformer primary. Moving clockwise the next pin conects to the primary center tap and one end of the field coil. The third pin conects to the other end of the field coil. The last pin conects to the other end of the transformer primary. Which pin is open? If it is the small pin or pin four, the transformer is bad. If it is pin three the field coil is bad.
: Steve
:
Steve,
Thank you so much for your advice. I was going to do some wire tracing to see what was open but testing the speaker connector pins as you suggested made it easier. Using your convention; holding the speaker plug facing me, starting with the small pin (as pin #1) and working clockwise, it appears to me that pin #2 only connects to one end of the field coil and pin #3 connects to the primary center tap and the other end of the field coil. Regardless, I have no continuity between pins 1&2 nor do I have any between pins 2&3. Its 150 ohms between pins 3&4 and 150 ohms between pins 1&3. 300 ohms between pins 1&4. This indicates what I feared most has happened; the field coil is open. Not sure what to do about that other than to try and find another speaker. Thanks for your help.

Lou

Lou,
If the speaker/field coil can be disassembled, it can be rewound, or if real lucky, unwind a few turns and find the only break. If you manage to disassemble it and see little green spots all over the winding, then its hopless finding just one break. I rewound mine on a GG Majestic 90B, but it came apart, even down to the separate cone/voice coil ass'y.

marv

:::I've restored two Philco Model 90s with the single type 47 output tube and now I'm working on one with push pull type 45 output tubes. The former have three-wire speakers with a four pin connector; one pin is not used. The earlier model with the 45s has a four-wire speaker and I have no continuity in one of the speaker pins (not the same pin not used with the later type 47 model 90s). Do I have a problem or is this normal? Since the open pin on my four-wire speaker is not the same open pin on my three-wire speakers, I don't want to simply test my four-wire speaker by plugging it into one of my restored model 90s having the three-wire speakers.
:::
::
::Lou, There should be continuity between all pins. Hold the plug with pins facing you, start with the small pin. It is conected to one end of the transformer primary. Moving clockwise the next pin conects to the primary center tap and one end of the field coil. The third pin conects to the other end of the field coil. The last pin conects to the other end of the transformer primary. Which pin is open? If it is the small pin or pin four, the transformer is bad. If it is pin three the field coil is bad.
:: Steve
::
:Steve,
:Thank you so much for your advice. I was going to do some wire tracing to see what was open but testing the speaker connector pins as you suggested made it easier. Using your convention; holding the speaker plug facing me, starting with the small pin (as pin #1) and working clockwise, it appears to me that pin #2 only connects to one end of the field coil and pin #3 connects to the primary center tap and the other end of the field coil. Regardless, I have no continuity between pins 1&2 nor do I have any between pins 2&3. Its 150 ohms between pins 3&4 and 150 ohms between pins 1&3. 300 ohms between pins 1&4. This indicates what I feared most has happened; the field coil is open. Not sure what to do about that other than to try and find another speaker. Thanks for your help.
:
:Lou
:

Someone suggested using a neon sign transformer (or perhaps an ignition coil??) to arc the winding back together. Kind of barbaric, but you might fuse a few surrounding windings and have results. As long as the resistance is similar to the original (no more than perhaps 50 ohms less), it will function well, if you can get the wires to fuse together well.

Never tried this myself. I'd probably just take the thing apart and have a peek, but Philcos are usually riveted together. Alignment is critical, so keep that in mind, should you cut the rivets. You will want either bolts with a smooth close fitting shank, or the next best thing--close fitting threads.

T.

:Someone suggested using a neon sign transformer (or perhaps an ignition coil??) to arc the winding back together. Kind of barbaric, but you might fuse a few surrounding windings and have results. As long as the resistance is similar to the original (no more than perhaps 50 ohms less), it will function well, if you can get the wires to fuse together well.
:
:Never tried this myself. I'd probably just take the thing apart and have a peek, but Philcos are usually riveted together. Alignment is critical, so keep that in mind, should you cut the rivets. You will want either bolts with a smooth close fitting shank, or the next best thing--close fitting threads.
:
:T.
:Thanks for your suggestions. This was the first time I tried to repair a speaker field coil and I ran into some beginner's luck. I think it would have been very difficult to remove the field coil from the speaker if I had to do that but as soon as I removed some of the paper covering, I saw that the discontinuity was where the lead-in wire connects to the fine coil wire. Soldered it back together, used a drop or two of Super glue to hold things together, reassembled it and finally, made some tests. Took about 30 minuites and the DC resistance is 3200 ohms, within 20% of spec.

Hey Lou,
Let's hope your good luck of '09 extends into '10.

marv

::Someone suggested using a neon sign transformer (or perhaps an ignition coil??) to arc the winding back together. Kind of barbaric, but you might fuse a few surrounding windings and have results. As long as the resistance is similar to the original (no more than perhaps 50 ohms less), it will function well, if you can get the wires to fuse together well.
::
::Never tried this myself. I'd probably just take the thing apart and have a peek, but Philcos are usually riveted together. Alignment is critical, so keep that in mind, should you cut the rivets. You will want either bolts with a smooth close fitting shank, or the next best thing--close fitting threads.
::
::T.
::Thanks for your suggestions. This was the first time I tried to repair a speaker field coil and I ran into some beginner's luck. I think it would have been very difficult to remove the field coil from the speaker if I had to do that but as soon as I removed some of the paper covering, I saw that the discontinuity was where the lead-in wire connects to the fine coil wire. Soldered it back together, used a drop or two of Super glue to hold things together, reassembled it and finally, made some tests. Took about 30 minuites and the DC resistance is 3200 ohms, within 20% of spec.
:
:

Superb! Always like it when things end like that!

T.