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COMMONWEALTH ERICSSON WALL TELEPHONE
ATCS 11/88
Many articles have appeared
in Australia on the Ericsson wall telephone, known to us as Commonwealth
Ericsson model. It first appeared before the turn of the century and was
adopted by the newly formed PMG Dept in 1901 as the standard magneto telephone
throughout Australia.
The models produced by L M Ericsson were:-
Type Old
cat no. No.magnets Ringer res. Wt.kg
AB 530
345 4
300 ohms 8.7
AB 535
-
4 1000
ohms 8.7
AB 590
346 5
2000 ohms 9.2
The above models were full size: a 3/4 size phone was produced with 3-bar magneto, for use on short distance services and a miniature model (1/2 size) with 2-bar magneto was available for intercom purposes. However, this discussion is only about the standard model which was elected for use in Australia because of its long distance capabilities.
A panel discussion on this phone took place at the September 1988 ATCS meeting, A lively discussion resulted, with considerable input form the panel, members of the audience and details submitted by members unable to be present. The phone was considered point by point and the following details in abbreviated form were the outcome. Some of the information may not be strictly correct and if anyone can make any corrections it will certainly be appreciated.
TIMBER CREST: Very Early models had a spear pointed crest; this was followed by the fairly plain crest with fleur-de-lis type incisions up to 1903 after which the carved crest (stamped?) was standard 
LINE TERMINALS:
Lacquered brass initially, superseded by 
frosted
nickel plate later. Terminal thread was generally 2BA but at least one
other thread type has appeared.
LIGHTNING ARRESTER: The standard form was two flat discs secured in place by recessed-top terminals. Circular insulated washers have variously been black ebonite, empire cloth or mica with several holes punched. It was thought mica might be English.
GONGS: Always the large type, brass, nickel plated, with raised section around hole.
BELL POSTS: Located by two screws and arranged to provide adjustment:
RINGER COVER: Early models were one piece stamped metal with rounded edge at top. Later were two pieces with square edge. The diamond shaped squiggle transfer stated to be most common The 'L M ERICSSON, PATENT, STOCKHOLM' transfer appears to be earlier. Maybe the diamond pattern was standard for Commonwealth Ericsson and the other transfer appeared on other imported phones. British made phones had 'ERICSSON, ENGLAND' on the cover. The lightning flash transfer down each side should be applied with the top and bottom points outwards.
RINGER MECHANISM: 1000 ohm for AB 530 and 2000 ohm for AB 590. Some phones have letter 'B' between bells to indicate use in bridging circuits.
BUTTON: Early models, plain ebonite button; later models, brass screwed-in fitting with ebonite knob on top. Depressing the button opens the circuit to bell when ringing out (silences bell) and short induction coil secondary (improves strength of signal when listening).
SERIAL NUMBER: Stamped on front edge of shelf. Date of manufacture can be ascertained from this. Significance of other numbers and letters sometimes appearing near serial number were not known.
MADE IN SWEDEN: Generally stamped on LH side of shelf but no invariably.
PAPER LABEL:
Attached
inside hinged front gives information on ringing ability of generator plus
date of manufacture (probably date of test).
LINE FUSES: Initially standard for Commonwealth Ericsson but deleted in later phones.
SELECTOR LINKS: Standard for commonwealth Ericsson. Selective ringing could be applied on party lines, ringing L1 to L2, L1 to E, L2 to E.
BATTERY TERMINALS: Early models have a long stem but later models had terminals set in wood block.
AUXILIARY RECEIVER HOOK: On front curved portion but not always provided. Some phones without hole and some have wood plug or metal disc to cover hole.
MAGNETO: Usually 4-bar but 5-bar available for long distance lines. Of sliding shaft type.
HOLE LH SIDE: Presume used to form radius on side pieces of battery cover. Side pieces identical except for larger hole on RH side for magneto handle. LH side plugged and fitted with small disc.
BATTERY COVER: Mild steel with wood grain finish. Up to 1903, flat across front with wood strip down centre. After 1903, battery cover centre was formed by pressing the steel, eliminating wood piece.
BATTERY COVER TRANSFER:
Initially a circular logo was used featuring skeletal phone in centre.
After 1904, transfer changed to incorporate 'L M ERICSSON' above plain
skeletal phone and 'STOCKHOLM' below. Phones manufactured in UK had skeletal
phone only in the transfer. At some stage a change was made to depict the
skeletal phone in gold instead of silver.
CIRCUIT DIAGRAMS: Only supplied in British made phones when it was pasted inside the battery cover.
BATTERY SHELF: Heavy steel plate painted black. Early models simply a flat plate secured by screws along back edge. Later models had substantial return on plate and secured by screws into back of board.
BACKBOARD: Substantial timber (about 1" thick) generally in on solid piece, but sometimes with a vertical joint to join two pieces of timber together. Some phones have appeared with a vertical piece each side, filled in top and bottom with separate pieces of timber.
TYPE OF TIMBER:
Mostly
walnut but occasionally in oak, 
the
oak models also being made in Sweden. This phone did not appear to have
used veneer as so many other models did. TIMBER FINISH: Plated finish was
always nickel - never renovate with chrome plate.
TORTOISE SHELL PROTECTOR: Attached to LH side to protect woodwork against damage by handset. Material was actually celluloid, finished in tortoise shell pattern, which as it ages tends to shrink and crack over the years.
HANDSET: Early models had thick microphone, wide groove wooden hand grip and ebonite ear cap. Changes evolved gradually but by 1903 the handset had thin type microphone, fine groove ebonite grip and ebonite insert on receiver, held in place by knurled metal ring. Cords were green or brown, terminating in 4-pin plug.
COMMONWEALTH CIRCUIT:Made specially for Australia to connect handset receiver and auxiliary receiver in parallel instead of standard Ericsson procedure of connecting them in series. This was simpler and assured continuity of use in the event that a cord or receiver became open circuited.
