Tait TM8100 mobiles Service Manual page 439

Several Keys Faulty
Figure 14.12 PCB layout of the function, scroll, and selection key circuitry
top side
bottom side
TM8100/TM8200 Service Manual
© Tait Electronics Limited November 2007
The keys can be grouped into columns and rows of three or two keys, as
illustrated in Figure 14.11.
If one column of keys is faulty:
1. Visually inspect the associated resistor and diodes for open or shorted
circuits.
F2 key R620
F4 key D602
scroll-up key
If one row of keys is faulty:
1. Visually inspect the associated resistor for open or shorted circuits.
F3 key
F4 key
right selection key
Fault Finding of Control Head with Graphical Display
F1 key R621
right selection key D620
scroll-down key
R623 scroll-up key
scroll-down key
left selection key
F3 key R622
left selection key D604
R624 F1 key R625
F2 key
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