Clock No. 36 Mark Nos. 234, 235 & 236 (Early types).

Mark 234 = Magneta
Mark 235= Gillett & Johnston
Mark 236 = Gent's of Leicester

Note:- Versions made before May 1936 did not have an internal Advance/Retard key or a 2000 ohm resistor on the 1 second contacts.
There is a diagram at the bottom of the page to show these types.

This is issue 'C' with issue 'D' below.

Issue 'C' above, with Issue 'D' below.

Issue 'D' above, with pre 1936 early types below.

Clocks that are wired as below were used with Figure 33 from Technical Instructions, XI (1927) and later, Diagram GMT 26 (1925 updated 1936), which was prior to the introduction of the GMT 34 & 35 units in 1936. As external parts such as the Relay, No. 90A are no longer available, the wiring in the clock can be modified along with the addition of a 2000 ohm resistor allowing it to function with either a GMT 34 or GMT 35 unit. It would also benefit from an added external Advance/Retard key switch such as a 'Key 212A'.

The diagram below is a reconstruction using the wiring from a 1932 Gillet & Johnston version of the clock.

Points to note:-
1) These types had no internal resistor on the one second contacts
2) 6 and 30 second pulses can be considerably longer (700ms-1000ms)
3) There was no internal Advance/Retard key
4) Any external A/R switch should be connected to the 6 second pulse
5) Additional wiring (and a 2000 ohm resistor if using the 1 second contacts) are necessary to use these clocks with either a GMT 34 or 35 clock unit

For further info, please refer to Figure 33 from Technical Instructions, XI (1927) and also Diagram GMT 26 (1925 updated 1936).