Yaesu FT-901DM Maintenance Service Manual page 93

SERVICING
(3) Partial reception (a) Poor reception on * Low VCO output or VCO unlocked
one or more bands (see section on COMMON CIRCUITS)
(some bands OK) * Defective band switch
* Defective TCrao, (160m)—TC2s06
(10m), C2401 (160m)—C2406 (10m)
(4) Self-oscillation on (a) Oscillation with * Defective 6146B, Rioos. Rizo3, Li701
receive HEATER switch on * Defective Li701. Coa
* Defective Ris, Ris, Riors Risors Cea,
Cro
* Defective Qisos, Qisos (PB-1717)
(b) Oscillation with * TX 12V line shorted to RX 12V line.
HEATER switch Check at each board, TX/RX switch-
either on or off ing diodes and switches
(5) Marker inoperative (a) RX OK, no marker * Defective NB/MARK switch
signal heard Check voltage at pin 4 of PB-1846
and PB-1685. Should be 12 volts
nominally
* Defective X¢o1
* Defective Qe,2
* Defective Doos
| (b) 25 kHz marker * Defective Seo:
inoperative
(6) REJECT inoperative (a) No notch action * Defective RLso;
* Defective X41
* Defective Dios
* Defective Qari
* Defective REJECT switch
(7) APF inoperative (a) Low or no output, * Defective Qsos , Qsos , Qsoe
serious distortion