Motorola Gm3688 Service Manual Top File

The Motorola GM3688 is a mobile radio designed for the Professional Commercial Radio (PCR) market. It is part of the GM360/GM380 family but features a different control head design. This manual covers:

When you finally access the PDF, focus on these core "top" sections first: motorola gm3688 service manual top

| Symptom | Likely Cause | Corrective Action | |---------|--------------|--------------------| | Dead (no power) | F1 (10A fuse) blown or Q1001 (voltage reg) short | Replace fuse, check reverse polarity protection diode CR1002 | | Low TX power | Q101 (final PA) degraded or LPF section misaligned | Re-tune L401, L402; replace PA if Vgs > 4 V with no output | | No RX audio | Audio amp IC400 (TDA2003) failed or squelch stuck | Check C410 for leakage; test pin 4 of IC400 for >6 V DC | | PLL unlocks on TX | VCO modulation varactor failure or bad solder joint on loop filter | Reflow C220, C221; measure Vtune (should vary with channel) | The Motorola GM3688 is a mobile radio designed