The SMPS (switched-mode power supply), often just called the adaptor, converts household 230V AC into the low-voltage DC that runs the RO booster pump and solenoid valve. A failing SMPS is one of the most common reasons a purifier suddenly stops.
Signs of a faulty SMPS
- Purifier completely dead – no pump, no light.
- Pump starts slowly, runs weak, or stops after a few seconds.
- Adaptor gets very hot or smells burnt.
- Pump works only sometimes, especially when the voltage in your area is low.
- A buzzing or clicking sound from the adaptor.
If you have a multimeter, check the DC output at the connector while the pump is running. A reading far below the rated voltage points to a weak SMPS.
How to choose the right SMPS
| Check | What to match |
|---|---|
| Output voltage | Same as your pump. Most domestic pumps are 24V DC; some high-pressure pumps use 36V. Never fit a 36V SMPS on a 24V pump. |
| Current (amps) | Equal to or higher than what the pump needs. Typical domestic units use about 1.5–2.5A. A higher amp rating is safe – the pump only draws what it needs. |
| Connector | Same plug or wire type as your old adaptor, or a model with bare wire ends for connection. |
| Protection | Overload and short-circuit protection help in areas with voltage fluctuation. |
24V vs 36V – which is better?
Neither is “better” on its own – the SMPS must match the pump. 24V is the standard for most domestic purifiers. 36V pumps are used in some purifiers that need more pressure. Some adaptors offer dual 24V/36V outputs for flexibility.
Replacing the SMPS
- Unplug the purifier from the wall.
- Note which wire goes where (red is usually positive).
- Disconnect the old SMPS and connect the new one the same way.
- Mount it where it can stay dry and has some airflow.
- Plug in and check the pump runs normally.
See our RO SMPS and adaptors (from ₹349).
Frequently asked questions
Can I use a 24V 2A SMPS instead of 24V 1.5A?
Yes. Same voltage with a higher current rating is fine.
Why does my RO SMPS keep burning out?
Frequent voltage fluctuation, moisture near the adaptor, or a pump that is drawing too much current because it is failing.
Does the SMPS also power the solenoid valve?
Yes, in most domestic purifiers the same 24V supply runs the pump and the solenoid valve.
Need help choosing the right part? Send a photo of your RO or its model name on WhatsApp (96252 23245) and we will tell you exactly what fits.
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