Quasar60 DRSSTC build using universal driver/interupter

[davekni]

Hydron described technique well.  I rarely use separate flux, but the solder's flux core type makes a HUGE difference.  Buy solder with fully-activated rosin core ("RA" for Rosin-Activated).  Avoid "no-clean" or "RMA" (Rosin-Mildly-Activated) flux core solder.  Leaded solder is definitely easier, but lead-free works too if its flux is good.  (We aren't allowed leaded solder at work.)

Another trick I learned for fine-pitch SMD parts:  Tack down the first pin as Hydron described.  (I usually tack down the other corner pins too.)  Then solder each side with a continuous run of solder bridging all the pins.  Then go back with solder wick to remove the excess.  The solder wick removes all the bridges.  Takes a little practice to adjust the wick size and/or technique to remove enough solder without removing all the solder, but it's much easier than soldering individual pins when pitch is under the 1.27mm of SOIC packages.  Sometimes I use this on SOIC as well just because it's easy.  (This technique of soldering groups of pins together is especially useful when there are power-plane connections soaking heat away from some pins.  A fine-tip iron has trouble heating the power pins against this heat load.  With group soldering, I can use a 6mm chisel-tip to solder SOIC and smaller packages.  The large tip has no trouble heating power pins in spite of close plane connections.  Removing solder with wick also works well with a large tip.  There's no need to do any work on individual pins.)

Final suggestion:  Make sure your iron is hot enough.  Chips remain cooler when soldered easily and quickly with a hot iron.  A marginally-hot-enough iron makes soldering take much longer, time for more heat to conduct into the part.

[Hydron]

No argument with what davekni said - I didn't go into drag soldering as it's not really needed for the UD2.7, and I'd get the basics down first. There are some good videos on youtube showing technique too.

[Zipdox]

Get a decent pair of tweezers, some flux and some good leaded solder.

Tin one pad first (a corner for a SO package, whichever is easiest ergonomically for 0805 etc), use tweezers and iron to melt the solder on the pad while placing and aligning the part, then finish other pads at your leisure (you may need to revisit the first pad again to touch it up later). Adding flux before putting the part down will help a lot, especially with clearing bridges etc and with smaller parts, but you can probably get away without it for the UD2.7 if you have good flux-core solder (still get some if you can though!).

Can take a little time to get the hang of it, especially if you get solder bridges etc (less likely with SO sized packages), but once you're up to speed I find it significantly faster than through-hole work.

[RoadReaper]

Hello,  Have been swamped at work so I have not had time to get to my work shop much,  I am still waiting on one of the parts for the UD2.7.  I have also order a interrupter from Loneoceans labs and ordered the finishing part from mouser.  Have a few questions on finding s backordered part,  the Mouser part number is 661-EKZN350E221MH15D. Aluminum 20% UCC electrolytic capacitors radial lead. Drop the 661 and you have the manufacture part number,  this part is on back order till the end of January.  I have tried Digikey and they don't even offer it.  Any Ideas on were to find 3 of them?  Another question,  the optical receivers and the transmitters did not come with a nut to mount them or the cap to thread on it.  I tried searching mouser and digikey for a cap and hardware but did not find any.  Any healp would greatly appreciated .  Thanks.
 

[Zipdox]

Is tbat a critically specific electrolytic cap or something? Tell me if I'm wrong but can't you just buy an alternative cap with similar ratings?

[davekni]

I agree with Zipdox, any similar part should work.  Is it 220uF at 35V?  That's my guess based on the part number.

[Zipdox]

Yeah that's it, I checked the datasheet.

[davekni]

Any 220uF 35V part that fits mechanically should be fine, as it's just filtering rectified line frequency.  (If this were filtering a high-power high-frequency switching regulator, then other parameters would matter more, ESR and RMS current rating.)

[RoadReaper]

I was concerned about the ripple current rating the one listed in the BOM was rated at 1.6Amps,  ever thing else I was finding was .25 amp to 1.25 amp,  I didn't know how critical this rating was.  after scrolling through many pages of parts I found an exact match.  Wish I would have found it yesterday when I placed the order for the finishing parts to the MIDI2 controller I just got.  would have saved me a second shipping fee.