Midland Radio SP-300 - Manual (Page 28)

MAXON
SP-300 HAND HELD
Page -25-
May 2001
TROUBLESHOOTING GUIDE
SYMPTOMS CAUSES COUNTER MEASURES
1. Complete discharge of battery (7.5v+/-10%) 1. Replace battery
Unit does not Work 2. Fuse blown up (4a) 2. Replace fuse
3. 5v voltage source 3. IC1 (5v+/-0.2v)
1. Low battery (lower than 5.6v) 1. Replace or charge battery
Warning Tone & No Work 2. Pll error 2. Check TCXO/ VCO/ PLL IC
3. Filtering error 3. Check LPF (IC407)
4 .EEPROM fail 4. Re-programming
Defective RX Audio 1. No audio at speaker 1. Replace speaker or check wire
2. Busy lamp (yellow Color) is o.k. but no Audio 2. Check tone ch, audio amp(IC6) 300hz
HPF (IC410) Sw IC (IC402B, IC411)
1. Defective ANT sw 1. Check D5,D6
2 .Defective front-end 2. Check Q601
Bad RX Sensitivity 3. Defective dbm 3. Check D9,T2,T3
(-10 to -60db) 4. IF IC 4. Replace IC5
5. VCO level drop 5. Rx VCO level>2dbm
6. Change of 1st local Frequency 6. Retune TCXO
1. VCO frequency change or level drop 1. Repair RX VCO
Defective RX 2. Defective voltage source 2. Defective IF IC(IC5)
3. IC1,Q1,Q3
1. Defective 12.8 MHz TCXO 1. Replace TCXO
PLL Error 2. Voltage source for Rx VCO/TX VCO 2. Check RX VCO/TX VCO
3. Defective PLL IC 3. Replace IC2
Low TX power Output 1. APC 1. Re-adjust RV1
1. TX buffer 1. Check Q16,17
No TX power 2. Power module 2. Check Q501,502,503
3. APC control 3. Check Q22,D4
No modulation 1. Condenser mic 1. Check mic
2. Sw IC & mic amp IC 2. Check IC411, 410, 405, 401,404
No s.a.t.(tone) 1. 250 hz LPF 1. Check IC406,407,411
2. RV403 adjustment 2. Re-adjust RV403
No programming 1. Short protector VCC 1. Check 6v on Q412, 413
2. Defective programming lead