Lathe work light broken how to fix

Hi John,
I misunderstood the problem. I thought it was just one sample of the bulbs that was at fault. I think your diagnosis of the problem is correct. The MR16 LED lamps I have taken apart use an MC34063 switching regulator as a constant current source. I suspect by the time the 24 volt AC is rectified the peak voltage is exceeding the voltage rating of the regulator chip.

petro1head,
I find that most of the time when switching regulators / electronic transformers fail causing the fuse to blow that the high voltage switching device (High voltage transistor or mosfet.) has gone short circuit. Very often a number of other devices then get destroyed which is why they are not worth trying to repair. Your use of an external low voltage supply will make it safer than the original as there will be no mains voltage at the lamp unit. I think putting the transformer in the base of the light defeats the reason for using a low voltage bulb.

Les.

I'v got a 10W LED flood light, it has an electronic power supply that takes any flicker to a higher frequency than anything that's going to effected by strobbing, the side effect of that is radio frequency interference(RFI), I cured that by running it through an isolating transformer. Battery operation would eliminate the RFI, and a low frequency battery charger of the Wall Wart type is all that's needed.

The modern florescent bulbs operate at about 35kHz, the old tubes at 50Hz switched of and on at each cycle.

Ian S C

For what my advice is worth, DON'T go to 24V Halogen bulbs, unless you ensure adequate ventilation of the lamp housing, and availability of replacements.

Most certainly, do NOT feed a mains voltage lamp via the original wiring and switching. It must be upgraded to mains voltage to be safe.

My oriental lathe, came with a 24V 50W lamp, (running off the low voltage safety interlock supply) but the lamps did not last too long, and the bulbs seem to be unobtainable in Peterborough, UK., but bought ten from the supplier of my lathe, when I had the chance.

Mine used to fail quite regularly, until I filed a couple of diametrically opposed slots, with a 5/16 rat tail file, in the edge of the "reflector" to improve ventilation. Can't remember when I last changed a bulb (long may it remain so!) So obviously, the original set up allowed the lamp to overheat.

The protective glass needs to be removed fairly regularly to clean off the oil and grease that collects on it. The blue swarf is a bit more difficult to shift!

Have also had a couple of LED lamps which flickered at full brightness (no failed LEDs), which I ascribed to part of the bridge rectifier going open circuit, so that the LED is only fed on one half of the cycle. So compact that not possible to locate components for check or replacement. PITY!

Have two mains voltage (ex Industry) worklights on the Mill/Drill, and one over the Fitting bench, which now have cool and bright GU5 fitting LEDs; so far so good!)

Recently fitted a £9.99 Lidl LED strip light above the lathe, this gives a light level seemingly as good as the ten year old 65W Ceiling mounted fluorescent tube. Resisted the temptation to go for the maximum allowable and join 3 together. Would probably need dark glasses to work, if I had succumbed.

Howard

I get mine from here **LINK**

Readily available.

My lathe is lit by 3 12v halogen lamps with solid state transformers and is just about adequate. Last night one blew, and to finish the job I put on my 6 LED headlamp. What a difference ! Can't think why I never thought of it before, good light, good colour, cost £3. Also have used my rechargable LED inspection lamp, this also gives good contrast, seems the LEDs are a bit different to some others. BTW I have little hair to worry about.

I bought g4 bulbs, WRONG The origional is a G6.35 rated at 25W (24V).

I can buy either G6.35 20W (12V) or 35W (12V)

Will the 35W be too hot for the unit and if so go for the 20W?