Waris HT Power On Issue
Description
This is a problem I've seen an HT1250 200 MHz
- With battery on, but power switch off, radio cannot power up when switched on
- With battery off and power switch on, radio will power up when battery connected
- with battery off and power switch off, radio will boot, then immediately power down when battery connected.
- With battery on, power switch on and battery on, radio will power off when switched off
Power Circuits
The CPU measured the battery voltage from MECH_SWB+ line. If it goes low, it begins an orderly shut down of the CPU and radio systems.
Upon MECH_SWB+ the SWB+ is turned on via Q400 going low through Q405 and summed via CR440 ultimately actuated by Q403, which has an RC time constant for about 300ms on it. This turns on the voltage regulators, boots the HC11 and it talks to the ASFIC telling the ASFIC to output logic into the CR440, and keeps the radio powered up after the RC time constant turns off Q403. This takes the switch out of the radio power until it's turned off. When it's turned off, the radio detects a low voltage on the MCU analog input used for the low_battery indicator. This allows the MCU to execute and orderly shutdown.
