Service BulletinAmateur Radio Division

Subject: TS-120S - Repair NotesDate: December 18, 1979

TS-120S Repair Notes

General Problems
Analog Dial Calibration OffMechanical adjustment
Loss of Digital DisplayCheck P5/J5 on Carrier Unit
Power on Meter MaxRF gain turned max CCW
VFO DriftSee SB-827
PLL Digital NGPll unit D15
15 Meters NGBroken wafer on BCD band switch or
connectors on PLL and RF units
No RX or TX 10M onlyQ16, 74LS163 on PLL unit bad
No CW FilterShort across pins 1 and 2 J29 IF unit
Analog Dial OffPerform VFO tracking adjustments at 50 and 450
No 15MCore broken on VCO transformer for 15M
3.5 and 7 Band SameShort at bandswitch under IF unit

Transmit Problems
Carrier in SSBRF unit D2 and/or D3 shorted (see SB-832)
Smoke at FinalCheck for burned L10 and L11, L40-1011-04 (100uH)
also check for long ends of wire shorted to case
TX Audio BadCheck the carrier point adjust and make
sure that the final bias is set to 150mA
High IC in RXBad finals
28.5 HF OscillationTighten ground screws at Relay unit X41-1250 (see SB-844)
Low TX out 40M50W on 40M and 10W on 10M bad finals
Low RF out all bandsQ12 SN16913 on AF GEN unit, or 2SK19GR bad
No TX all bandsL25 on RF unit is open (small green inductor)
No Digital No TXQ12 mixer on the PLL unit bad
Intermittent SSB AudioPin 5 of J5 on AF unit loose
No Key or TXD26 and Q24 2SA562 on AF GEN unit bad
No TXR8 220 ohm resister at key jack burned open
(use shielded line for CW key)
15M OscillationInstall ferrite bead on base of first Mic amp
Q18 on AF GEN unit (see SB-844)
No TXLoss of AVB voltage at RF unit, Q9 2SA473 on
FILTER unit or 6 volt Zener diode

Receive Problems
No CW, No AudioSidetone oscillator Q25 on AF GEN unit 2SC1815
Receiver Sensitivity DownT1, L34-0696-35 on RF unit shorted (see SB-831)
SSB Receive Audio BadIF shift control turned max CW
No RXPins of CW filter not cut off after installation shorting IF to ground
No Digital No RXQ26 mixer on the PLL unit bad

©1979 Kenwood