Before you send it in: five minutes of checking
A large share of the lamps that reach us for repair have no fault in the lamp head at all — but a power supply with no output voltage or a loose contact. Both can be established at home. This sequence has proved itself in our support work.
Step 1: which generation do you have?
That determines what you are looking for in the first place.
- MKIII – separate power supply outside the lamp. The power supply is the most common point of failure and can be replaced on its own.
- MKII – transformer fixed inside the unit. There is no external power supply, so step 3 does not apply.
How to read the generation from the model number is in our article on Lumeno model numbers.
Step 2: the plug connections
Pull the barrel plug at the base of the lamp out once and push it firmly back in. Test the socket with another appliance. Sounds trivial — but in practice it is one of the most frequent causes, particularly at workplaces with power strips under the desk.
Step 3: the power supply (MKIII only)
If the power supply has an indicator light, it has to be on. If you have a multimeter, measure the output voltage at the barrel plug — it must match the value on the type plate.
Pay attention to the voltage. Most series work with 20 volts, the 851X series with 24 volts. A power supply with the wrong voltage is the second most common fault after total failure — and a 24-volt supply on a 20-volt lamp can cause damage. The full allocation is in the article "Which power supply fits my magnifying lamp?".
If the measurement gives zero volts, the case is clear: the power supply is defective, the lamp is fine. We stock replacement power supplies individually.
Step 4: the loose-contact test
If the lamp flickers or fails only in certain arm positions, that points to a loose contact — usually in the cable running through the articulated arm, which has been moved with it over the years.
The test from our service practice: with the lamp switched on, move the connections of the individual LED segments carefully and watch whether the light reacts. Likewise move the articulated arm slowly through its range. If the lamp responds to movement, it is a connection, not the LEDs.
A safety note: do this only on models with an external power supply, that is, in the extra-low-voltage range. On an MKII with a built-in transformer please do not open anything — mains voltage is present there.
Step 5: individual segments out
If only individual sections of the LED ring stay dark while the rest lights normally, that is a fault in the lamp head. This is a service case — nothing can sensibly be repaired at home here.
The typical fault patterns at a glance
| Symptom | Probable cause |
|---|---|
| Nothing at all, no reaction | Power supply or plug connection |
| Flickering, depending on arm position | Loose contact in the supply lead |
| Individual segments dark | Fault in the lamp head |
| Lamp gets very warm, then goes dark | Power supply underrated or defective |
| Arm sinks, light is fine | not an electrical fault – see article on the articulated arm |
What we need from you
If you want to take it further after these steps, three pieces of information help us — and save us both an exchange of emails:
- the full model designation from the type plate, including the MK suffix
- a brief description of the fault pattern: nothing at all, flickering, or partial
- whether the fault changes when you move the cable or the arm
A photo of the type plate is often quicker than typing the number. After that we will tell you whether a spare part is enough or the lamp should come to us.
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