VIZ WP-705A Power Supply Troubleshooting

Original article can be found here: 


1. Blinking Display: Check power supply +5V.  Check U215 thru U218.

2. Improper readings: Check power supply +5V.  Check regulator U213 and U214 for normal operation.  Check voltages on U217/218.

3. Won't Zero: Check voltages on U217/218.  Check R227/228.  Check +5V supply.  Check C210/211.

4. No display but power supply has output: Check power supply +5V.  Check on-board regulators U213/214 for normal operation.  Check continuity of all VCC paths to active chips.

5. Unstable display: Check power supply +5V.  Check all voltages on U217/218.  Check capacitors C203/204 for opens or leakage.  Check C211/212.

6. Missing segments on displays: Check each display that exhibits a bad segment by replacement.  If this does not correct the problem, checvk U215/216 for output conditions.

7. Decimal point won't move.  Check S202/203.  Check CR201/202 and CR210/211.  Check Q201/202.  Check R221/222.