Changing emitter from the star, budget soldering station

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arenat
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Changing emitter from the star, budget soldering station

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Last week needing to swap a diode from the star then  I search on youtube what's there about, some guy use a oven, other a hot air pistol and so on..

Well, my first idea was attaching a standard heatsink to a working 60 W soldering iron holding it whith a vise. That work great .

Then I remember a broke ceramic heating element from a Goot soldering iron which was resting  in a drawer for ages.

This arrange comply with the time graphic provided by Cree when the heating element is  around

40 Watts.

To make things short the pics

 

The central path of the heatsink  is conveniently 22 mm wide. A unwanted however welcome characteristic is the form factor , very handy , comfortable since allow to rest the hands over the table

Edited by: arenat on 11/29/2010 - 11:36
FlashPilot
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Great idea! I also like the thermocouple to monitor the heat. I have a precision stove. Maybe I'll have to experiment with an iron skillet and a thermocouple to see how well I can regulate the temperature for such projects.

arenat
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dead P31 driver

 

Work fantastic, this is the P31's dead boost driver  I was able to remove C3 and C1 and then put again in place both.The DC DC converter is PAM2803 which were in short .

 

With this R180 limiter resistor the current through the led is 528 mA.

I'm tempted to fix it just for fun taking the IC from one SKU 25505 received today from DX.

arenat
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Fixed,the inductor and the pcb are way better than the generic drive sku25505 therefore worth the swap.

P31 driver

 

Wondering why this driver die on 14500  since is the same as the stock C78's became as the only difference the sense resistor.In this one is R180 in the C78 is R270.

At first with 4 smd 1 ohm resistor in parallel  = R250  the current at the led was 360 mA very well regulated  between 1 V to 2,8 V.... with  14500 is direct drive at 1,6 A.

Then with a .22 ohm added in parallel the current increase a lot but the regulation decrease a lot also.

Vin 1,296 V   Iin 2,11 A  Vout 3,34 Vrms    Iout 570 mA  V sense resistor 65 mV

Vin 2,592 V    Iin 1,01 A  Vout 3,54 Vrms     Iout 780 mA  V sense resistor 89 mV

 

 

arenat
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Summarized tips/tutorial.

Material,60W soldering iron ( if need to buy locally since all DX and such are selling is top of the crap )Solder paste,a standard heat sink not too big with a central path around 22 mm, iron wire to hold it tightly, look the pics in the thread, a tiny tweezer which can hold securely the small ceramic substrate of the emitter.

An emitter victim to practice, postpone the real one after when the confidence reignedLaughing

Skip the wood box, the thermocouple and the broken heating element of the thread, once the heat sink is attached hold it horizontally with a vise .

Unsolder

Put the star over with some thermal grease behind to improve the contact. Power up the soldering iron and wait patiently ( three to five minutes ) . Look carefully, when the solder melt take out the emitter with  tweezers and put it over a wood or something like that, it's ceramic and a thermal shock could break it.

When the melt temperature is reached cut the power since for a while keep increasing even not powered

Take out the star and beat it against something hard while hot to clean the solder excess.

Solder

Wait till the plate is cold or warm, do not put a cold emitter over a hot surface.

Clean the star with alcohol , put the solder paste , not much , just a small quantity is enough, read about in the Cree's literature to more deep approach.

Put the star/emitter over the plate and wait, when the solder melt wait around 15 seconds and  take out the star of the plate, this latest is the more delicate manoeuvre, could be doing with the tweezer or simply pushing out of the plate to a wood holded beside .

Some last, the hottest part is near the tip ..

Done.

I thought i went too far with the tips , hope you understand, i suspect reading it is a nighmare ..haha