Czy wolisz polską wersję strony elektroda?
Nie, dziękuję Przekieruj mnie tamgva10158-a1 brak zasilania na wtórnym
For GVA10158-A1 with no voltage on the secondary side, first determine whether the SMPS is starting at all. In this module, commonly used in JVC micro systems such as UX-G48 / UX-G49, the supply is typically built around the MIP419MD primary-side switching regulator. The most common causes are:
Start with these measurements:
| Test point | Expected result |
|---|---|
| Main primary electrolytic capacitor, usually 100 µF / 400 V | about 310–325 V DC on 230 V AC mains |
| If only ~250–270 V DC or unstable | suspect dried main capacitor |
| If 0 V DC | check fuse, NTC, bridge rectifier, mains path |
| Secondary rectifier diodes | no short |
| Output rails to ground | no very low resistance short |
| MIP419MD drain/source path | no short circuit |
Be careful: the primary side is connected directly to the mains and can hold over 300 V DC after unplugging.
Before any measurement or repair:
Do not connect an oscilloscope ground clip directly to the primary “hot” ground unless you know exactly what you are doing. It can short the mains through the oscilloscope earth.
Measure DC voltage across the large electrolytic capacitor on the primary side.
For 230 V AC mains:
\[ V_{DC} \approx 230 \times \sqrt{2} \approx 325 \text{ V} \]
Expected value: 310–325 V DC.
Interpretation:
| Measurement | Likely cause |
|---|---|
| 310–325 V DC | mains rectification is probably OK |
| 0 V DC | blown fuse, open NTC, damaged bridge rectifier, broken track, bad mains input |
| 250–270 V DC, strong ripple, unstable | dried/open primary electrolytic capacitor |
| Lamp limiter glows brightly continuously | primary or secondary short likely |
In this chassis, the primary electrolytic capacitor is a very common failure point. If the capacitor has lost capacitance or has high ESR, the SMPS controller may not start even though some DC voltage appears on the meter.
Recommended action: if in doubt, replace the primary electrolytic with a 105 °C low-ESR or good-quality general-purpose 400 V capacitor of the same capacitance and voltage rating.
The GVA10158-A1 supply is commonly associated with the Panasonic MIP419MD integrated switching regulator. This device contains the primary-side switching control and high-voltage switching element.
With power disconnected and the primary capacitor discharged:
If the MIP419MD is shorted, do not replace it alone. Also inspect:
A failed snubber can destroy a new MIP419MD immediately at power-up.
A typical offline flyback converter starts as follows:
If the start-up resistor is open or the VDD capacitor is dried, the converter will not start.
Symptoms:
Check:
Because the exact pinout depends on the IC package and board revision, confirm with the MIP419MD datasheet or board markings before probing.
A complete lack of secondary voltage can be caused by the converter entering protection due to shorted output load.
With power disconnected:
Common secondary faults:
| Fault | Effect |
|---|---|
| Shorted Schottky/fast rectifier diode | SMPS goes into protection, no output |
| Shorted output capacitor | heavy load, no start |
| Shorted audio amplifier IC | supply collapses or converter pulses |
| Shorted 5 V / 12 V regulator downstream | secondary rail clamped |
| Cracked solder joint on transformer/diode | intermittent or no output |
In JVC micro systems, also suspect the audio power amplifier stage. If the amplifier IC or its supply line is shorted, the power supply may appear completely dead on the secondary side.
A practical method is to isolate output branches by lifting jumpers, coils, fusible resistors, or disconnecting the load connector, then checking whether standby voltage returns.
The feedback loop normally consists of:
If the feedback circuit is defective, the supply can:
Check:
If you cannot test the optocoupler reliably, replacement is often reasonable because it is inexpensive.
Use this order:
Visual inspection
Cold resistance checks
Primary DC measurement
Controller start-up check
Snubber/clamp inspection
Secondary isolation test
Feedback loop check
Power-up through lamp limiter
Most probable parts to check/replace:
Do not replace the MIP419MD before checking the surrounding snubber and secondary side. If a secondary diode, snubber capacitor, or feedback fault remains, the new IC may fail instantly.
For GVA10158-A1 with no secondary power, first verify the primary DC bus: about 310–325 V DC should be present on the main 400 V capacitor. If it is low or unstable, replace the primary capacitor. If the primary bus is correct, check the MIP419MD start-up supply, start-up resistors, snubber network, and possible short circuits on the secondary outputs. Also inspect the audio amplifier supply branch, secondary rectifier diodes, optocoupler, TL431, and solder joints. Power the repaired board only through a current limiter for the first test.