Cal. 7D56A
36/44
Technical guide
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Coil block resistance
61 Seconds coil block: 2.00k
Ω
-– 2.45k
Ω
62 Hour and minute coil block:
Coil for driving hands: 1.00 k
Ω
-– 1.25 k
Ω
Coil for detecting generation: 270
Ω
-– 330
Ω
60 Generating coil block: 360
Ω
-– 420
Ω
Note: Measure the coil block resistance after installing each coil block to the movement, checking that stable
measurements are obtained.
Remarks on checking the hour and minute coil block
* The motor driving the hour and minute hands uses a special driving system so that they move
quickly to indicate the current time immediately after the time relay function is activated. The
hour and minute coil block has two layers of coils, one for driving hands and the other for
detecting generation, and it is necessary to measure the resistance of each layer of coil.
* The illustration below shows the patterns to which the probes of the tester should be applied
to measure the resistance of the respective coils.
Pattern for checking
the coil for detecting
generation
Pattern for checking
the coil for driving
hands
a
b
A
B
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Checking for leakage between coil for driving hands and coil for detecting
generation
* If the hour and minute hands do not move properly when the time relay function is activated,
that is, if they remain stopped or will not move smoothly, check for the leakage between coil
for driving hands and coil for detecting generation. This checking is required only if such a prob-
lem is found.
If leakage is detected, replace the hour and minute coil block with a new one.
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How to check the leakage
1. Make the tester ready for measuring the resistance.
2. Apply the probes of the tester to 1 “A” and “a”, 2 “A” and “ b”, 3 “ B” and “a”, and 4 “B” and “ b”,
respectively, to measure the resistance.
3. If the four measurements obtained are all infinitely great, that is, if the resistance was unable to
be measured for all the four cases, there is no leakage between coil for driving hands and coil for
detecting generation. As a guideline, there is a leakage if measurements of less than 2 k
Ω
were
obtained.
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