Anemic over stove lighting replaced with warm XPG goodness!

I regret that I didn't take photos before this project began. I have a 40 year old house – when we bought it almost 4 years ago it had a new smooth top stove – with a BLACK top – but an 11 year old over-the-stove microwave with 2 anemic little 25 watt bulbs. Not only did they get hot, burn out often, and cost $3 a pop, they did not provide nearly enough light.

Don Mcleish posted details HERE (scroll to the bottom of the page) of a project in which he upgraded a similar situation. That photo essay was an inspiration to me – thus this photo essay on my project.

I'll say up front – it'll take a while to recoup the costs, but I didn't do it to save money – I did it to improve the lighting. Still, at $3 every time a bulb is replaced, and regular replacements, maybe it won't take TOO long after all!

Materials:
Aluminum Square Tube 1" X 1" 1/8" Thick – 1 foot long – for mounting the LEDs and to provide heat sinking
6 – CREE XPG Q4 Warm LEDs mounted on Indus 20mm stars
Xitanium AC/DC Driver – 700mA – 17 watts
Arctic Alumina Premium Thermal Paste
Various wires, etc. Used 14 gauge solid copper wire

So, although you can't tell much, this is the setting...black - dark - hard to see


So take a 12 inch aluminum square tube...


Mount 6 Cree XPG Q4 Warm (3000CCT) LEDs on Indus Star MCPCBs using Arctic Aluminu Premium Thermal Adhesive


Drill a few strategic holes for wire routing...


My work isn't exactly 'neat', but it gets the job done in a workmanlike sorta way... The setup is 2 banks of 3 LEDs wired in parallel


Joined the negative lead at the end of the string...


Routed the wires out the end of the tube


Taped down the main connections


Joined the 2 series and mounted the bar inside the existing reflector


Underside of the old reflector


Snapped it back into the exisiting spaces provided - I removed the sockets and hardware from the stock lighting, but did so in such a way as to be able to revert back to the original arrangement very easily if need be


Mounted the Xitanium driver directly to the metal base of the microwave. Plenty of room - and it's a natural heat sink! Used a stock AC cord to plug into an outlet and make certain everything worked before I tied into the microwave's power leads.


Tied everything together. Doesn't look neat, but the original leads were preserved and simple point solder connections tied new wires into old




Tied everything together, closed everything up and voila! Let there be light!


6 LEDs all glowing nicely



Looks bright and clean




A few interesting notes - the switch is 2 stage. I measured with a multi meter and it puts out 120VAC on high, 64VAC on low. I wondered if it would even light the LEDs on low, but it does - but it has flicker like slowed down PWM. No matter, we switch right through low to off anyway -

I'm no electrician, but I thought it was important to have your hot and neutral defined. However, the leads coming to the lights were unmarked. I tried them both ways and they read 120VAC either way I connected to the leads. And the lights worked connected either way.

Whatever the case, the stove top is now nicely lit. I doubt that I'll ever have to deal with a burned out lamp. I left the lights on for an hour and measured with my handy dandy infrared thermometer - 80 degrees F at the LED - 78 where the driver makes direct contact with the metal bottom of the oven.

6 LEDs X 3.0Vf X 350mA (driving parallel) = 6.3 watts consumption from a driver rated for 17 - plenty of head room. Prior to the mod, my meter measured 250 lux in the center of the stove - after the mod - 720 lux!

I am very pleased - more so than I was with my laundry room project. Next? Under cabinet lighting!!

:thumbsup:

run4jc said:

A few interesting notes - the switch is 2 stage. I measured with a multi meter and it puts out 120VAC on high, 64VAC on low. I wondered if it would even light the LEDs on low, but it does - but it has flicker like slowed down PWM. No matter, we switch right through low to off anyway - they are using diodes to cut the AC freq in half causing the old incans to turn on/off at 1/2 the rate 60Hz usually runs (not noticeable by human eyes with incans) thats whats causing the low freq flicker.

I'm no electrician, but I thought it was important to have your hot and neutral defined. However, the leads coming to the lights were unmarked. I tried them both ways and they read 120VAC either way I connected to the leads. And the lights worked connected either way. yes, one leg is still "hot" while the other is "neutral" in ANY AC application. AC allways jumps from +/- to -/+ x#/sec..... in the US it's 60 times a second or 60Hz. most devices won't have an issue with this in a single phase system, the only concern i'd have worried about is the chassis of the microwave being neutral/ground and the occasional mishap with hot wire shortouts, be it thru the lamps or thru your body, but thats still a minor concern, unlikely to say the least.

Whatever the case, the stove top is now nicely lit. I doubt that I'll ever have to deal with a burned out lamp. I left the lights on for an hour and measured with my handy dandy infrared thermometer - 80 degrees F at the LED - 78 where the driver makes direct contact with the metal bottom of the oven. i'd still keep an eye on things for a while, with the microwave right above & running, thats added head, and especially with the cooktop right below, thats ALOT of added heat, if the metal heatsink is getting hotter than the diodes it's try'n to cool.... kinda defeats the purpose.

6 LEDs X 3.0Vf X 350mA (driving parallel) = 6.3 watts consumption from a driver rated for 17 - plenty of head room. Prior to the mod, my meter measured 250 lux in the center of the stove - after the mod - 720 lux! Nice Improvement!

I am very pleased - more so than I was with my laundry room project. Next? Under cabinet lighting!!

:thumbsup:

Click to expand...

all in all, i'd say great job! very good improvement over the old bulbs and even better use of the stock supplys. and it looks wonderful... hope it gives you years of service.

FRITZHID said:

the only concern i'd have worried about is the chassis of the microwave being neutral/ground and the occasional mishap with hot wire shortouts, be it thru the lamps or thru your body, but thats still a minor concern, unlikely to say the least.

Click to expand...

Interesting - perhaps I did cause a short when testing the wires, because the internal 250V 20A fuse blew. Off to Home Depot I went, picked up a new one (plus a few extras ), replaced the fuse, and all was well. I do have a rudimentary understanding of alternating current, but your explanation is helpful - thank you!

FRITZHID said:

i'd still keep an eye on things for a while, with the microwave right above & running, thats added head, and especially with the cooktop right below, thats ALOT of added heat, if the metal heatsink is getting hotter than the diodes it's try'n to cool.... kinda defeats the purpose.

Click to expand...

That is a very legitimate point. According to the spec sheet, the "maximum operating temperature" of the driver is 194F, and that has been a concern. I know that Don Mcleish did the same mod and I don't think he ever had any issues. The first time we really 'heat things up' with the stove/microwave I'll do periodic readings to see how it looks.

I think the LEDs will be fine - I've done heat/torture tests on XPGs in a couple of different settings - temps well over 225F - and they survived...

I suppose that the 'good news' is that all of this is modular and replaceable. Don't wanna have to replace it, but it could be done! Of course, that would defeat one of the purposes of doing the mod in the first place - avoiding having to replace lamps!

Thanks for your comments! Good stuff - I appreciate it. :thumbsup:

I enjoy seeing a nicely documented mod like this. I think Thanksgiving will be the ultimate stress test for the system. If it survives a day when the oven runs for hours and then the microwave gets quite busy, well then it will survive anything. Well done!

Very nice, Dan! I'm hoping to have some time this winter to do some in-home lighting upgrades, and will look back to this for some guidance!