guard ring?

Heat gun/ + heat pad under...

I don't want to melt everything else, and there's stuff on the back side of the board, too. My manufacturing people could do it for me, but they're busy. I applied my biggest Metcal tip and waited about 5 minutes for the big diode to finally let loose. I suspect that the solder didn't fully flow under the new tiny diode, but it runs cool.

Anyhow, that's a cute little schottky without a guard ring problem.

TTman wrote in news:ppr5sh$3mq$ snipped-for-privacy@dont-email.me:

snip

I agree. Even a chamber is a good idea. Bring the assembly UP in temperature so that the transition to reflow the part is less of a jump.

starts adding the reflow heat source (hot air, etc.). A 200 degree transition on a hot part is far easier to impart than a 330 degree jump from ambient.

Schottky can be pretty bad for snubbing, depending. The peak current can hit the guard ring diodes and you get big recovery loss. The capacitance is huge.

You'd have to add a shunt to be sure what was going on with the other one.

Regular diodes can have faster recovery than schottky-guard-ring recovery, but they also cost forward as well as reverse recovery.

Tim

I was going to suggest a good size iron, and solder sucker. Then an exacto, under the tab.

George H.

Hot air machines are super cheap, and don't melt anything but what they're pointed at. Assuming the only thing melting is solder. You probably shouldn't have melty things like electrolytics and film caps nearby on an SMT board, anyway, but a heat shield (aluminum foil) keeps that feasible.

Tim

John Larkin wrote

Anyways no way to tell without seeing what that diode is doing. Snubber = flyback diode here?

"Tim Williams" wrote in news:pprker$6d5$ snipped-for-privacy@dont-email.me:

With PCBs that have heavy via and high via counts near heavy parts even a single hot air jet can be detrimental to a board.

Bringing the entire assembly up in temperature OVER ambient means less thermal WORK has to be done to do the job, AND less overall stress occuurs on the whole thing.

One brings the entire assembly temp up (at least the area surrounding the rework location), THEN use a direct hot air jet to reflow the part.

They have benchtop setups for this.

Well, you set it too high then (somewhere north of 260C).

And yeah, if you have too much thermal mass for this to work, you need a preheater.

Tim

"Tim Williams" wrote in news:ppsf6u$970$1 @dont-email.me:

That was his entire beef. Hard to desolder... preheat was the suggestion a couple of us gave.

Error (500) Something went wrong. Don't worry, your files are still safe and the Dropboxers have been notified. Check out our Help Center and forums for help, or head back to home.

Looks fine to me. Anybody else having problems seeing my links?

Some companies don't allow their employees to see Dropbox, or to receive verious email attatchments.

No problem at all here. Nice photos.

Same here. No problems.

Sometimes they don't work. Retrying later usually works. Those are working now.

Jasen Betts wrote in news:pq05cm$lfo$ snipped-for-privacy@gonzo.alcatraz:

Are you still on a POTS connection and a modem somewhere in backwoods hellville?

Replacing three schottky diodes with the cute little Microsemi parts helped my pulse generator efficiency a lot. They also solder into an SMB diode footprint, with some care to not short out.

My circuit still isn't as efficient as the Spice sim, so I've been prowling around with our FLIR imager to see where the heat is. Surprisingly (to me) at 1KV and 4 MHz pulse rate, the Phoenix output terminal block is hot.

I ripped out the metal bits from the unused center terminal, and it really cooled off.

Power consumption dropped by 3.4 watts.

I suppose the ham radio RF power guys already knew about stuff like this; I'm still learning.

Dremel?

Might have been the Great Internet Reset:

It was announced that some ISPs might have issues.

Mark L. Fergerson

No. And how the f*ck would a POTS connection cause dropbox to fail anyway? sometimes drop box is drop ball.