Open Museum Archive

PAX 222F Telephone Exchange
Object ID3395
Works No
Accession NoIF:2010:37
StatusOn Display
Category Telephone
Collection IDTelecommunications
Made BySiemens Brothers
Made InLondon, England
Description100 line Strowger PABX. Ex Croydon College.

The exchange can be dialled through the museum Asterisk server on Tel: 01239 350019 and asking the operator for "Croydon" plus a two digit number. Valid extensions include 18 and 11 (Wxchange Room)

Conservation/ Maintenance History
On Arrival

A number of damaged and badly adjusted line finders. After general maintenance the exchange appears to be in excellent condition and the first call was passed on the 17th of July, 2010.

General Maintenance

Exchange required maintenance work which was carried out over two days by a volunteer with Siemens experience.

Bakelite spacers behind at least one thermal relay in the selectors had tracked and blown fuses. Thermal relays are being bypassed (provide long term off-hook protection).

General cleaning was required and a faulty rectifier identified, unit now powered from the main 227 PSU.


Work carried out by D. Williams

1) G relay in common control had no residual ? (now set to 5mil) ? caused linefinders to step slowly or fail to step
2) Ringing machine intermittent start ? commutator cleaned up a bit ? needs a proper clean
3) L/F 2 Rotary hunt fail ? VMB adjusted
4) L/F 3 Rotary hunt fail ? VMB adjusted
5) L/F 6 Always busy ? earth on ?Test? wire ? U-points adjusted 6) Connector 7 No rotary ? Shaft sticking ? Adjusted and lubricated ? (Note - Thermal relay was disconnected)
7) Connector 8 ? Blows fuses ? Hard earth on battery wiring ? Thermal relay disconnected
8) Connector 9 ? Blows fuses ? Hard earth on battery wiring ? Thermal relay disconnected
9) Dial changed out in the 746 telephone on display
10) Several of the VMB and normal wipers are in a poor condition and could do with replacements.

2017 Exchange Maintenance Visit - David

Linefinder 3 – not stopping on level 9 – vertical interrupters adjusted All selectors and linefinder mechanisms lubricated Air blasted all banks

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