Zenith DVT654 Service Manual - 3. Test & Debug Flow

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3. TEST & DEBUG FLOW

TEST

NO

Replace power PCBA or

AC transformer.

YES

Switch on the Power PCBA

Repair or Replace Power PCBA

NO

Make sure the main PCBA don't

short on VCCs and switch it on.

YES

Check the regulators or related diodes.

NO

YES

Connect to PC RS232 Cable and

update the FLASH memory code.

Update FLASH

successfully?

A

YES

NO

1. Check 27MHz system clock.

2. Check system reset circuit.

3. Check FLASH R/W enable signal PRD,RWR.

4. Check RS232 SIGNALS.

5. Check FLASH Memory related circuit.

Check the AC Voltage

Power PCBA(120V)

Is the DC Voltage

outputs OK?

(5V,3.3V, 8V, 12V, -12V, 11.5V)

Is 3.3V and 1.8V DC

outputs normal on main

PCBA?