Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output
1) BTW, U302 looks like a voltage regulator. What is the part number?
2) You can test to see if it is shorted in circuit by numbering the pins 1, 2, and 3. Measure the resistance between pins 1-2, 1-3, and 2-3. Any reading under 30 ohms suggests it is shorted and warrants desoldering and verifying out of circuit.
3) Having said that, the voltage regulator may not be shorted, but it may not be outputting the correct voltage. We have seen a lot of cases where the regulator fails to produce the correct voltage. If it fails low, then there probably isn't a lot of collateral damage. If it fails high, it may take out some components.
For example, if an AS1117-33, where the suffix denotes the output voltage, fails high and outputs 4.1V, it could damage sensitive components. If it fails low and outputs 2.9V, then there is probably no damage.
4) On one yet to be repaired main board, I have 2 voltage regulators that are clearly shorted between all pin combinations.
1) BTW, U302 looks like a voltage regulator. What is the part number?
2) You can test to see if it is shorted in circuit by numbering the pins 1, 2, and 3. Measure the resistance between pins 1-2, 1-3, and 2-3. Any reading under 30 ohms suggests it is shorted and warrants desoldering and verifying out of circuit.
3) Having said that, the voltage regulator may not be shorted, but it may not be outputting the correct voltage. We have seen a lot of cases where the regulator fails to produce the correct voltage. If it fails low, then there probably isn't a lot of collateral damage. If it fails high, it may take out some components.
For example, if an AS1117-33, where the suffix denotes the output voltage, fails high and outputs 4.1V, it could damage sensitive components. If it fails low and outputs 2.9V, then there is probably no damage.
4) On one yet to be repaired main board, I have 2 voltage regulators that are clearly shorted between all pin combinations.
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