Sanyo PLUS T35 Service Manual

DEGITAL COUNTER BLOCK1.FMfrequencyfineadjustment(1)SetFMSGto98.000MHz,1kHz,75kHzdev.(100%modulation),andfeedthissignalintoFMANTterminal(300-ohm)of theset.(2) Tune in by tuning the tuning knob, and turn on quartzswitch (locked).(3) Tip IF OFFSET to FM side. That is, short-circuit byconnecting the tip of R023 connected to FM/AMterminal (pin No. 12) of IC 002 to the earth. Then thesecond place from the bottom (digit 2) flickers.(4) Turn SVR RO39 (10K ohms, balanced) and adjust untilthe display becomes 98.000 and digit 2 stopsflickering.FM FREQUENCY FINEFM-SGO00 000 O00EEE O]Cha)2.AMfrequencyfineadjustment(1) Produce signals of 1000 kHz with AM SG and 4,000 Hz,30% modulation at the external modulation terminal,andapplythe signals intoAM ANTterminal.(2)Tuneinbyturningthe tuningknob, andstopwheretheoutputreachesthelowestlevel.(Seewaveform.)(3)TipIFOFFSETtoAMside.Thatis,short-circuitbyconnectingthe tip ofR023connectedtoFM/AMterminal(pinNo.12) of IC002toV,,(+9.4V).Thenthesecondplacefromthebottom(digit2)flickers.(4) Turn SVR R040 (10K ohms, balanced) and adjust untilthe display becomes 1000 and digit 2 stops flickering.AM FREQUENCY FINEAF OSC AM-SGQUARTZ SAMPLING LOCK1. PrincipleThe quartz sampling lock (OSL) is designed to comparethe phase of FM loca! oscillation frequency with thereference frequency generated by crystal oscillator,convert the fluctuations of local oscillation into DCvoltage and apply it to a variable capacity diode (vari-cap diode) in order to control the local oscillation. Thecrystal fundamental oscillation frequency is 6.4 MHz,which is divided to 1/128, so that the local oscillationcan be locked at 50 kHz intervals using the 50 kHz fre-quency as the reference frequency.2. Circuit descriptionPart of local oscillation is taken out from FM _ locatoscillation through buffer Q106, and is amplified in0401.Ontheotherhand,fundamentaloscillation (6.4MHz)andfrequencydividingareperformedbyQ411{afrequencydividerbuilt inoscillationcircuit),andasquarewave outputof50kHzisobtained. Next,thewaveformisshapedby0410(TTLNANDgate)(seeFig.1),andhighspeedpulse of50kHzisobtainedinthe output.ByswitchingQ403withhighspeedpulse,Q402operateswhen0403isON.Therefore,sincethepreviousRFAMPoutputisimpressedtothebase ofQ402,thephaseofthelocaloscillationwhenQ402isONcanbe detected.C4648Pisachargepump,andholdstheoutputafterphasedetectionuntilanext pulse(Fig. 3).LOCAL OSG Xtal - OSCDIVIDERWAVE FORMPHASE COM.OSC SCOPEijTUNING POINT