Tait T850 II Series - Page 186

C5.10 T856/857 Fault Finding M850-00
31/09/98 Copyright TEL
5.7.1.3 CTCSS Encode
Y
Y
Y
Replace IC810.
Use PGM800Win to
select a channel
with a CTCSS tone
pro
g
rammed.
Check serial communications.
(See separate flow chart).
Cannot select a channel
Check IC810 pins 24, 25
& 26 (microcontroller).
Are there 5V square waves at
the CTCSS frequency?
Check IC830 pins 1, 7 & 14.
Are there 9V square waves at
the CTCSS frequency?
Check IC830 pin 8.
Is there a sine wave
at the CTCSS frequency?
Check RV805.
No tone
Check the filter circuit for bias
problems and/or short circuits.
Distorted tone
No square waves or
uneven mark/space ratio
No square waves or
uneven mark/space ratio
Check IC830 circuitry
and repair/replace.