20S converted to 20SC

[zaphod01]

This was an impulse BIN purchase. Looked like an old perch so I took a shot. Rear of perch has 20S punched over. Stamped 20SC on the other side. Cables look to date from the conversion. Older patent date on base. Should clean up nice.

[Sargeguy]

It's really hard to find an original 20-S in original condition.  They are always converted to 20-ALs or 20-SCs. 

[poplar1]

I wonder why they didn't just add a C to the right of the original 20 S marking, instead of starting over--and even on the new stamp, they still centered  it as if intending to stamp 20 S rather than 20 SC. In other words, the C still looks like it was added since 20 SC is not centered.

[dencins]

The only difference I have been able to find between a 20-S and a 20-SC is the receiver.  The 20-S has a 122 OST receiver while the 20-SC has a 143.  Possibly the 20-S to 20-SC stamping was done as part of a refurbish.  Seems like a lot of effort for just changing a receiver.

Dennis Hallworth         

[Sargeguy]

They probably had one guy crossing out the old markings and whoever re-furbished the phone put the new markings on.

[poplar1]

They probably had one guy crossing out the old markings and whoever re-furbished the phone put the new markings on.

Early union rule? Seriously, I've seen others where a letter or number was added--most common is the 51 AL converted to 151 AL where a 1 is added in front--rather than starting over.

[poplar1]

The only difference I have been able to find between a 20-S and a 20-SC is the receiver.  The 20-S has a 122 OST receiver while the 20-SC has a 143.  Possibly the 20-S to 20-SC stamping was done as part of a refurbish.  Seems like a lot of effort for just changing a receiver.

Dennis Hallworth         

I seem to recall the difference is the insulated transmitter on the 20 SC  and 20 BC vs. the uninsulated transmitter on the 20 S and 20 B.

Also, the new (not converted) 20 SCs and 20 BCs had drawn lug holders (perches).

[Sargeguy]

Maybe as the old phones were returned the uninsulated transmitters and OST receivers were removed and the old code scratched out, and they were lined up to be upgraded and sent back into service.  Once the refurbisher finished them he would re-stamp them with the new code.

There seem to have been a variety of methods of re-marking candlestick perches.  I had a 151-AL that had 51-AL another 151-AL that was originally a solid perch.  There is no other mark than 151-AL.  I also have a 151-AL that has 20-AL on the front.  I have also seen a 151-AL with two 1s stamped over the 50-AL.   Some stamps seem to be the entire 151-AL while others just have a gouge in front of 51-AL

[poplar1]

1908 Catalog shows a 20-P with insulated 271-type transmitter, so the C in 20-PC, 20-BC, 20-SC etc. must mean something else???

[zaphod01]

I'm still a rookie on candlesticks (I have 6) so this may or may not be something out of the ordinary. I began work on my 20S/20SC last night and removed the receiver. The receiver itself was in wonderful condition and I'd rate it as 9.5 on a scale of 1 to 10.

However, the cord had a couple of small spots on it so I disassembled the receiver to detach the cord. I was very surprised that the connection was pins instead of lugs (photo attached). I'd never run across a 75Z attached with pins.

Is this unusual? Could this be the original 20S cord?

[poplar1]

More  often than not, converted and remanufactured phones got new cords. The cord shown (with pins) is suitable for either a 122 receiver or a 143/144: the 122 needs pins only while the 143/144 will accept either pins or spade tips. 20-S probably had green cords when new.

[poplar1]

WE Catalog #7--1929--still shows Code no. 549 cords--with "29-cord tips" (pins) on one end and "63-cord tips" (spades) on new 1040-AL (non-dial) desk stands. The 1051-AL (dial) is shown with an R2A receiver cord (92-cord tips [spades] on both ends).

[zaphod01]

The transmitter face on the 323 was rough. I had a 323BW transmitter and decided to do a face transplant. My only previous transmitter adventure involved installing a 337 to replace a bulldog. The 323BW, the 337 and the bulldog were all two-wire connections. The 323 was a single wire connection (pin type). When I removed the 323BW transmitter from the face plate, there was a small pink celluloid dot at the contact point. The 323 had no celluloid dot.

Rookie questions: 

Would a 20SC, by definition, have had the single-wire transmitter connection?

What does the celluloid dot do?

[dencins]

323 transmitters were insulated.  Sometimes they were used as repair on uninsulated candlesticks.  A common approach used to change a 323 from insulated to uninsulated is to connect a wire from the ground (second wire) screw on the bridge to one of the screws that holds the bridge to the faceplate.  This bypasses all the various insulated areas on the transmitter,  On an uninsulated candlestick the ground then becomes the body of the phone. 

The "small pink celluloid dot" is actually a mica dot that insulates the carbon module from the diaphragm.  Early version of the mica dot were clear mica and later the mica was dyed red to make it easier to find.

If you want to change the candlestick from uninsulated to insulated you also will need to either add another terminal to the switch plate or use a different switch plate.  Also the switch hook will need to be isolated (insulated) from the switch blade.  This may mean a different switch hook with a phenolic insulator.

The other option is to leave the candlestick uninsulated and put a wire on the transmitter like described above.

If a 20SC had only one wire to the transmitter then it would have been uninsulated.

Dennis Hallworth     

[zaphod01]

The uninsulated 323 had the thin wire to the mounting screw as you described. I moved it over intact. I'll grab my extra 534 and test it today.

Is there a replacement material that can be used in the place of mica? My first thought was to make a dot out of a dial card cover.

I've got the candlestick thing bad. I'm up to 7 and I'm selling off everything else.

Thanks for the info!

Robert