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Which WD 553/653 Variation Do I Have?

Started by extremecinema, January 31, 2015, 07:23:03 AM

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extremecinema

Purchased this on Ebay a few days back, and while I did so fully aware that the unit will need complete rewiring, the white (beige) inductor coil (marked "1" "2" "3" "4") is completely throwing me, as I cannot find it in any of the 553 or 653 models I've seen online.

Please let me know what WD model I'm dealing with, or if anything is obviously missing.

Thanks!

unbeldi

#1
Welcome!
Your induction coil is a No. 20 coil which was standard equipment on common battery subscriber sets until about 1919, when the No 46 coil became the standard.  This mean this is a sidetone instruments, and therefore not a 653, but a 553.  This is to say of course, that now it is a 553, as someone post-factory cut the dial opening into the housing and added the dial.

Another user had a similar instrument recently, without wiring, but using an AE case:
http://www.classicrotaryphones.com/forum/index.php?topic=13500.msg141578#msg141578

The wiring for your set would be identical. You can use that circuit diagram.

extremecinema

Thank you!

If this is a 553, from what I gather it has the wrong dial and mouthpiece?

Apologies...I am seasoned electronic hobbyist, but I am unfamiliar with the distinctions between phone models. 

unbeldi

The dial is indeed not original.  Someone cut the dial opening into the front and added it.  Since the base unit was made before ca. 1919, we know that it was not a dial equipped unit originally.

The transmitter has also been changed.  The transmitter holder contains an F1 transmitter element which became standard equipment ca. 1934 and many subscriber sets were retrofitted with it. So it is not improper, and is perfectly acceptable as a refurbished piece of apparatus.

unbeldi

#4
The difference between a 553 and a 653 is the type of induction coil used, and therefor the type of audio circuitry in the unit.  The increment of +100 from 553 to 653—the same rule applies to most other phone models of the time—indicates the upgrade to an anti-sidetone circuit (AST).  AST circuits compensate for the electronic feedback of audio signal generated in the transmitter to the receiver, which causes the speakers to hear themselves very loudly. Since the audio signal that should be transmitted to the distant calling party is also driving the local receiver, this causes energy dissipation locally and a weaker transmission signal.   By introducing a phase-inverted cancellation signal with a third winding in the induction coil, the local loss of energy is avoided and the speaker receives only so much audio volume of themselves to assure a comfortable conversation, as if face-to-face with someone.  As an electronic hobbyist you are perhaps familiar with the concept.

The typical induction coil you would find in a 653 or any other AST device would be a No. 120, 146, or 101A induction coil. The 120 was only issued as a refurbished No. 20 coil by adding another winding. The 146 may have been made newly at factories for a short period between 1930 and 1934, or else it was also added during refurbishing.  The 101 was introduced also in 1930, but didn't show up in subscriber sets that we find today until ca. 1934 or 5.

extremecinema

#5
Again thank you, this makes sense, as the dial has a 1939 date on it.

Also, while the induction coil is clearly visible, where is the condenser?  I don't see it in the photos; is it under the terminal strip?

Since much of the wiring is missing, what would be the best type of wire - gauge, stranded/solid, and insulation - to use?

unbeldi

#6
There should be a large rectangular metal can underneath the wooden terminal strip.  The capacitor could be a 1 µF (most likely) or a 2 µF value.

Wiring gauge is not critical,  ca. 20 gauge, anything an electronics hobbyist would typically have. There are many picture of the internals of these units here on the forum. Sometimes one can find original Western Electric cloth insulated wire on eBay, but it's expensive.  You can purchase original looking receiver cords online as well, for a decent price, ca. $15-$20, I think.  These would be repro cords made on original Western Electric equipment, that is still operating.  The company is Old Phone Works in Canada.  They are also on eBay.  You could also post a request in the classifieds here, someone may have spare cords, willing to sell.

[PS:  looks like you already have a receiver cord. I overlooked that.]

unbeldi

#7
Your dial is a No. 5H, which contains an extra terminal.  Install a wire bridge between R and BB, to make it equivalent to the No.2 dial that is indicated on most schematics of the time.

poplar1

#8
The No. 20 induction coil may be older than the phone, since "Western Electric" is stamped in the metal rather than being on a decal. Either a No. 20 or a No. 46 will work.

No. 20  or No. 46          To Terminal Strip
Terminals

Primary:
1                                            L1
2                                             R

Secondary:
3                                             C
4                                            GN

Diagram from TCI library:
http://www.telephonecollectors.info/index.php/document-repository/doc_details/2185-wall-telephone-hotel-sets-553-tl
"C'est pas une restauration, c'est une rénovation."--François Martin.

unbeldi

#9
I am wondering whether the cover was even on the base originally.  If it was a 533 originally, it should have had its transmitter mounted in the center of the front, yet I cannot see any old mounting holes in the center and it does not seem they could have been in the area of the dial opening, which appears being cut.  Were there 533s with the transmitter in the lower half?

The cover is made from copper, not steel, as far as I can make out, so the base should be copper too.  Is it?   It seems made from steel, judging by the wear around the wall mounting holes.

extremecinema

Anybody know what the "SC93A" on the backplate means (also note the JAN 1941).  Can't find any reference to this.

poplar1

The steel housings were copper plated before being painted.
Might SC refer to Signal Corps?
After the 533A was manufacture discontinued, a manual set consisted of 553A + an apparatus blank.
"C'est pas une restauration, c'est une rénovation."--François Martin.

extremecinema

#12
Is it worth my while (in an effort  to make the unit more period authentic) to change out the dial to a 4H, and the transmitter to a 332?

extremecinema

Quote from: unbeldi on January 31, 2015, 03:52:17 PM
I am wondering whether the cover was even on the base originally.  If it was a 533 originally, it should have had its transmitter mounted in the center of the front, yet I cannot see any old mounting holes in the center and it does not seem they could have been in the area of the dial opening, which appears being cut.  Were there 533s with the transmitter in the lower half?

The cover is made from copper, not steel, as far as I can make out, so the base should be copper too.  Is it?   It seems made from steel, judging by the wear around the wall mounting holes.

You are correct...the cover is copper and the base is steel.

I refurbishing it as a 553...I'm using a 2AB dial, 323BW transmitter, 75Z receiver. 

The cover has been stripped, and professionally repainted.  You are correct, the dial hole was hand cut (pretty decently), but the transmitter hole and the hanger slot on the side are WE original cut.  Since 533s had the transmitter in the center, I still have no idea what this cover was originally.  Any other guesses?

In the meantime, I have rewired the base (and yes, it is steel), and it tested it with a 102 wired D2 phone, and it dials/rings; still not sure what it was a part of.

extremecinema

Quote from: poplar1 on January 31, 2015, 05:34:34 PM
The steel housings were copper plated before being painted.
Might SC refer to Signal Corps?
After the 533A was manufacture discontinued, a manual set consisted of 553A + an apparatus blank.

The dial hole is clearly not cut by WE...I've seen it stripped down, and it was done aftermarket.