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20AL with 4 wire line cord

Started by zaphod01, July 21, 2013, 12:13:34 PM

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zaphod01

Thanks for all the advice!

I'm ramping up the candlestick adventure. Several items on my watch list including a sidetone subset. Also looking at a couple of rough WE candlesticks. I am hoping to catch one at a reasonable price so I can take it apart and begin to understand the inner workings.

I really like the look of the 334A!
"Things are never so bad they can't be made worse." - Humphrey Bogart

poplar1

#16
http://www.classicrotaryphones.com/forum/index.php?topic=8785.0

A fellow member reminded me of a previous post about connecting a sidetone phone (3-conductor cord) to an anti-sidetone (AST) subset (normally requires a 4-conductor cord).

I tried this with a 202 (AST) by not using the black wire in the mounting cord, thus using it as a 102 (ST). It seems to transmit and receive OK, and there is no click in the receiver when you hang up slowly.  A person on the other end said the volume on his end was the same whether I was on the 202 or my 302.

There are a lot of unmodified candlestick phones---20AL, 50AL, 51AL with 3-conductor cords and hook switches that can't be used with Anti-sidetone subsets or 302 bases not only because of the cords but also because there aren't enough contacts in the hook switch. There are also a lot of 102s with 3-conductor cords. These 102s could be changed to 202s by just changing the mounting cord to a 4-conductor, but sometimes you don't have any 4-conductor cords. So, here again, you can use the circuit developed by Bell for use when stockpiles were low because of the war.

Maybe this will solve, at least temporarily, the problem of too many cracked 302s waiting to be made into anti-sidetone subsets and too many sidetone candlesticks with 3-conductor cords.

Red to L2/Y
Yellow to GN on the induction coil
*GREEN* to the Black condenser wire

(R terminal on the induction coil is not used)
"C'est pas une restauration, c'est une rénovation."--François Martin.

poplar1

584A (sidetone) and 684A (anti-sidetone). Although they look similar, the 684A has an additional wood terminal strip below the induction coil:

"C'est pas une restauration, c'est une rénovation."--François Martin.

zaphod01

Thanks! I bought a 'starter' candlestick from Doug Rose. I'm bidding on a 534 subset and a 533A wall phone.

Also bought a 684A with a Ray Kotke clear cover just because I thought it was beautiful. I'm building a nice 202 to go with it.
"Things are never so bad they can't be made worse." - Humphrey Bogart

zaphod01

I went to compare the wiring on my new 534A with the photo from earlier in this thread. Not only was it an exact match, it was the same subset!  :o

Works great!
"Things are never so bad they can't be made worse." - Humphrey Bogart

poplar1

Just about every metal WE subset on Ebay was converted from a 534A to a 634A either in the WE shop or in the field. They changed the 2-winding induction coil (46-type)l to a 3-winding one (146B or 101A), and added a second capacitor so that the talk circuit and ringer no longer shared the same capacitor. A few are conversions coded 634BA: these have a high impedance ringer which allows you to have more ringing bridges on the same line.

I'm surprised how difficult it is to find an unmodified 534A. The 334A with exposed gongs usually brings $75. The 295A also usually sells for a lot. Still, there seem to be more 334As and 295As available than 534As.

Did you ever open up this 20AL to see where the black wire goes?
.
"C'est pas une restauration, c'est une rénovation."--François Martin.

zaphod01

I've had enough experience with my other 20AL that I'm ready to open up the 4-wire next weekend. Now I understand where all the wires should go and I am really curious. I'll post photos if I find anything particularly interesting.

I tested the 534A with a 202 and the 4-wire 20AL. Both worked fine.

I bought my first E1 202 this week so I'll have a fun weekend. I'm hoping the E1 works and isn't stuck!

Thanks for the help!

Robert
"Things are never so bad they can't be made worse." - Humphrey Bogart

poplar1

Quote from: zaphod01 on August 12, 2013, 07:16:06 PM
I've had enough experience with my other 20AL that I'm ready to open up the 4-wire next weekend. Now I understand where all the wires should go and I am really curious. I'll post photos if I find anything particularly interesting.

I tested the 534A with a 202 and the 4-wire 20AL. Both worked fine.

I bought my first E1 202 this week so I'll have a fun weekend. I'm hoping the E1 works and isn't stuck!

Thanks for the help!

Robert

Robert, did you ever check the black wire? Hopefully someone didn't get in a hurry and cut it off if it wasn't needed!
"C'est pas une restauration, c'est une rénovation."--François Martin.

zaphod01

I got busy and didn't get to it. I received a D1/E1 102 Saturday and spent the day researching how to get the darn E1 apart. All but one bit came apart easily and I finally got brave and used my strap wrench.

I got my 684BX mounted to a correct, NOS back board. Wish I could find a couple of more of those! I bought wood to build a back board for my 534A.

I also built a mock-up of a mount for my Ray Kotke clear 684A. I know a guy who does wonderful things in clear acrylic. I'm going see if he can cast/build me an upright mount for the clear subset.

The cords should arrive for my other 20AL this week and I think I'll wait so that I can have them both apart at the same time. Base should be back from being re-felted. Bought more candlestick bits this weekend and I'm bidding on a 295A. I think I'm hooked on the older stuff!  ;D
"Things are never so bad they can't be made worse." - Humphrey Bogart

zaphod01

I tried to disassemble the 4-wire 20AL but had problems. The cords are so fat there is not enough slack to allow the bottom of the assembly to travel up the shaft. It's hung on the 'L' at the bottom. I didn't spend a lot of time on it and will try again tonight. I didn't want to force anything. Any suggestions?  ???

I got my 'box of parts' 20AL assembled into a phone. Finished up late, late last night and was too tired to hook it the the 534A but will test tonight.

"Things are never so bad they can't be made worse." - Humphrey Bogart

poplar1

If the phone is anti-sidetone (120AL) and wired as such, then when you remove the receiver from the hook, the yellow and black wires from the phone will be connected together. So, you can temporarily disconnect the yellow wire from L2Y and move the black wire to L2Y. You should now have dial tone and be able to transmit, but you won't be able to disconnect.
"C'est pas une restauration, c'est une rénovation."--François Martin.

zaphod01

Great! I'll give that a shot. The end of the black connector has a bit of solder on it and it looks like it was obviously used at some point. I hooked it up to the 684A as a 120AL and it seems to work fine. I'll try your test tonight.

I hooked my 'box of parts' 20AL to the 534A and it works! It arrived without any cords at all so it was OPW to the rescue. I was a little worried I might have wired it up wrong. I had the bottom re-felted and it looks pretty sharp.

I think I'm just about ready to start looking for a dial model and a headset model.

As always, thanks for the help!

Robert
"Things are never so bad they can't be made worse." - Humphrey Bogart

zaphod01

I tried swapping yellow and black and it produced the exact condition poplar1 described. I'm convinced it's wired as a 120AL. I hooked it to my 684A and all is right with the world.  ;D

On to other projects!

Thanks, guys!
"Things are never so bad they can't be made worse." - Humphrey Bogart

poplar1

Actually, I meant to disconnect the yellow wire completely for the test. That way you could see if the black wire is going to the transmitter.
"C'est pas une restauration, c'est une rénovation."--François Martin.

zaphod01

That's what I meant. The yellow was connected and the black was not connected (on the 534A). I disconnected the yellow and connected the black in its' place.
"Things are never so bad they can't be made worse." - Humphrey Bogart