Several Keys Faulty; Pcb Layout Of The Function, Scroll, And Selection Key Circuitry - Tait TM9100 Service Manual

The keys can be grouped into columns and rows of three or two keys, as

Several Keys Faulty

illustrated in
If one column of keys is faulty:
1.
If one row of keys is faulty:
1.
Figure 14.12 PCB layout of the function, scroll, and selection key circuitry
top side
bottom side
TM9100 Service Manual
© Tait Electronics Limited August 2005
Figure 14.11.
Visually inspect the associated resistor and diodes for open or shorted
circuits.
F2 key R620 F1 key
F4 key D602 right selection key
scroll-up key scroll-down key
Visually inspect the associated resistor for open or shorted circuits.
F3 key R623 scroll-up key
F4 key
right selection key
R621 F3 key
D620 left selection key
R624 F1 key
scroll-down key F2 key
left selection key
Fault Finding of Control Head
R622
D604
R625
413