Thanks CC. I think RMM stocks them also. Is this the same?
Yeah, I forgot he grabbed a big horde of them like I did. We cleaned that dude out!
He still has lots of interesting stuff all the time, that's where I get the inductors for the BLF SRK drivers and also the high grade ceramic capacitors that cost a fortune from Digikey. http://stores.ebay.com/RF-Basic-Store
So…just solder it in place and that is all?
Will it be OK w/4P3S?
Sure, why wouldn't it? A FET works just like a relay except with no moving parts.
I'd replace the original FET too, it's unlikely to be as good as the 70N02.
Comfy, the 103 resistor between gate and source, what purpose would that serve?
That's called a pulldown resistor. It just provides a drain for any leftover charge on the gate pin that might be remaining after the PWM signal turns off. Some controllers have internal pulldown resistors so the external one isn't needed.
I haven't replied to your question Krono because I saw you were in good hands. Only thing I can add is a heat gun will be very handy if you want to pull the stock FET. You will want the driver level while you heat it.
I don’t have a heat gun…will it be impossible to use a soldering iron for the FETs?
And I messed around too long and couldn’t get the 70N02s from RMM…and he is sold out…darn.
Ordered some of the other FETs he has…the International Rectifier IRFR3711ZTRPBF N Channel MOSFET - DPAK-2. Will these work?
Hmmm. Soldering a new one on will not be hard at all as you can hit each pad one at a time with your iron. If you want to remove the original one (I didn't bother doing that, but the suggestion sounds like a good idea), that will be difficult with such a large component. Hopefully, someone with experience doing that kind of thing chimes in.
Tractor Supply may still have some of those heat guns on clearance for $14.50. Some times Harbor Freight has their 1500W 2 speed heat gun on sale.
EDIT: Link added.
Thanks. Have you used that heat gun yet? Is it precise enough? It looks like it has a rather wide nozzle…not sure if that makes a difference or not…
Edited with more info.
I have used that TS heat gun for a few things, but not for reflowing yet. I expect it to work fine for that. I will try it out today on a automobile ECU I'm building and report back.
The HF heat gun I have used for reflowing many dozens of times. Works great, but it's definitely not for heating a precise component. It heats an area about the size of the nozzle and more to reflow temp. Then I use tweezers to pull the target component. GarryBunk has just started reflowing with a HF hot air gun. He could probably give you some good tips since he just learned how to do it.
EDIT: Finally, got around to reflowing with the TS heat gun. It works good enough for the price. I like the Drill Master from Harbor Freight better and it's currently on sale for $12.99.
And I messed around too long and couldn’t get the 70N02s from RMM…and he is sold out…darn.
Ordered some of the other FETs he has…the International Rectifier IRFR3711ZTRPBF N Channel MOSFET – DPAK-2. Will these work?
I could use some more help!
If you look above on the driver, the neg. wire seems to be touching the metal lip on the back of the existing FET. I removed the FET and will replace it, and add a second with IR FETs I received from RMM. My questions are:
1) Should new FET be soldered same way (with neg. wire soldered to lip of FET)?
2) What about the 2nd FET that I will be adding in the empty bay. Will the lip of this FET also need to be soldered to the neg. wire?
Thanks,
krono
Both FETs are in parallel, their tabs ('drain', in datasheet-speak) are connected by a common trace, the LED- wire is soldered to that common trace.
Do you own an ohmmeter?
I have the cheap HF DMM, but its on the way to CK for modding.
It looks like that the contact with the solder is just incidental due to close proximity of the pad and too much solder. As Comfy said, both FET Drain Pads and the LED Lead Pad are on the same underlying trace. You should have no issue with solder touching one or both FET tabs.
You might be able to verify by shining a very bright light through the PCB from underneath. That black top coat may block the light from getting through though. If you had a DMM you could check to seek that there is almost no resistance between the 2 FED Drain pads (with nothing connected to them).
LED -ve connects to the tab of the FET. If you reflow the FET to the board, connecting LED -ve as shown in the pic is fine. If just soldering source and gate, connect LED -ve to the tab… I highly doubt you’ll need two FETs in parallel since one alone wouldn’t be near its maximum limits.
I soldered the two FETs on the existing driver (boy do my soldering skills stink!). Output is still lame!!!
I don’t care about the driver anymore, and I’m thinking about jumping the 476 like you originally advised. If it blows the driver, I’ll just buy a new one from RMM.
So…you still think jumping the 476 might work…or should I remove one of the FETs?
That is a 6.3V 47uF Solid Tantalum capacitor, not a resistor. You definitely don't want to short over it.
Here is a product link:
http://www.aliexpress.com/item/SMD-tantalum-capacitors-47UF-6V-A-J476-100pcs/590619734.html
Removing a FET shouldn't improve anything. One good one is all you need, but removing one shouldn't improve anything. I only left the original stock on in place because I didn't feel like removing it. Can you post a picture? Maybe something went wrong.
I’m thinking the driver might be PWM limited if all modes perform as normal.