It’s been awhile since I built mine but it seems like the caps were slightly different sizes?
The image you provided said one is smaller and one is larger. I seem to recall that one was slightly “taller” component than the other?
Okay. One seems to be a tiny bit taller than the other. I’ll assume it’s the 10uF. It was hard to tell if it was my imagination.
Thanks DEL. I’m going to take a chance and go with this assumption.
Thanks is my first DIY driver, so it’s been slow going. The next one should go easier.
I’ll let you know if I can get the darn thing to work. I think my soldering has been pretty good though.
And thank you for seconding that Ohaya.
You’re welcome. I think I made similar comments about add’l instructions about the caps somewhere and I think someone answered there, but I can’t find it so far.
Okay. It’s finished. I’m going to rest my eyes for a bit then hook it up for a test.
I haven’t found the post yet, but I think that the info I got back was in:
Jim
Okay. I tested it and got nothing. Maybe a faint almost imperceptible glow for a second. Ain’t that a pisser. I wonder what went wrong. Could be anything.
Does it matter which way the MCU goes on? It’s looks identical on both sides.
I could test the board for connectivity, but I’m not sure where everything is supposed to lead to.
Yikes, most definitely yes - the MCU position matters. Again, it may be hard to see, but there's a circle or triangle on the MCU to mark pin #1, usually on the top, sometimes on the side. If you look under a glass at it, move it around to catch the right angle.
On the board pic above, you see the white asterisk marker just above the center LED+ pad? That marks MCU pin #1 position.
Also, you really need to buzz out all connections - on the whole board after assembly/reflow, but also off every MCU pin. Make sure all solder joints are truly good, and check for any bridges - you need to do close eye inspection - you really need to get a good visual setup - very important: magnification and light. I can do it with these ol eyes, and I work with a tech who is bout 70 who can see this stuff better than me, but it's all about the tools.
It does matter, and there should at least be a recessed round dot on the MCU, apart from the lettering, that dot should be on the side where the OTC is
Okay. Thanks for that guys. It seems I have the MCU on backwards. I can reflow the MCU, but do you think I probably damaged it. I’m installing the MCU on my second board now.
I wish there was a thread with detailed instructions for building these things.
Not sure if it survives or not, others may know better. Also the diode is important which direction it's installed. I think the FET is straight forward.
The diode protects the MCU from exactly that - reversal of gnd and Vcc, and since gnd is pin#4 and Vcc is pin #8, they would flip positions if the MCU is upside down.
This clear picture from Dale helped me building one (edit:I see now that Richard's lay-out is slightly different) :
Man! You guys are lifesavers.
I built a second board and it works perfectly. The first board should have worked perfectly too except there was no info about the MCU placement.
I reflowed the MCU on the first board, and it’s working fine. I was afraid testing it with the MCU backwards might have blown something.
Once you pointed it out, even with my eyes, I can now spot that dot on the MCU from a mile away.
djozz dug up that great pic. I've posted some in the past as well, but tough to find them, probably buried in some of wight's threads.
That is a lovely soldering job on that driver. Mine never come out that clean. I don't know if it's something I'm doing or the type of flux or solder I'm using.
Mine come out look'n pretty much the same. Best way is to be conservative with the solder paste, pre-heat the board before doing the reflow. I use a hot air gun that has low air-flow, even spread.
It's not hand soldered, Dale does reflow as well, I believe hot air.
I must say, mine came out totally professional looking. My old paste was dried up, so I ordered a tube of Kester solder paste with a 22ga. nozzle. This is the best paste I have ever used. It has the perfect consistency and flows effortlessly from the nozzle. It melts fast and doesn’t bridge. It’s a bit pricey, but the shipping fee at digikey was so cheap I actually saved money buying more expensive solder paste. It was packed in ice and shipped overnight.
Nice Ouchy! I got a tube from Richard a while back I keep in the frig. He packed a large syringe completely full of Kester - I can't use that much in a lifetime, but tell you the truth, I've had small batch's in small syringes go bad, and this seems to stay moist forever - maybe because it is a big batch keeps it from drying up, dunno, but literally goin on more than a year, maybe 1 1/2 years on this syringe and still moist.
I actually don’t use a hot air re-flow, I use a hot plate on our glass convection stove top. Either a 1/8” thick 6” round piece of 304 SS or a 1” thick x 6” round piece of 6061.
I usually buy a stencil from OSHStencils.com, I use Kester Solder Paste and with the stencil I wipe it on with the supplied “credit card” The results are outstanding. 
I’ve done up to 24 drivers at once, with 2 sets of 12 on fully connected panels, then wired em and put springs on em and tested em while still intact. I always prefer to flash the MCU first, but it will flash after being built as well.
Here’s a pic of 20 all on the same panel…
Ahh - nice setup! Lot of history/info here:
https://budgetlightforum.com/t/-/30080 - wight's driver, very similar to the RMM one.
Pics in OP, Post #22 showing the solder paste, Dale's pic in post #78
https://budgetlightforum.com/t/-/27210 - my thread on the earlier OSHPark 17mm driver we were using at the time
OP shows the phases for reflow, good reference thread:
post #124: RMM's detail specs on voltage dividers
https://budgetlightforum.com/t/-/31102 - this thread is on the newer FET+1 boards
Also good reference thread - post #149 is a detailed pic (mine), not as good as Dale's though. Hot plate method is better