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Just a heads up for those of You building a SDS Cap Board. When I applied power to my new cap board last night there were four small pops then smoke came rolling out. I checked the caps four times when I assembled so what's the deal? After some investigation and sharp eye on the flukes range, I found that the bleeder resistors were 330 ohm NOT 330K ohm Yellow_Light_Colorz_PDT_13 . The low resistance also takes out the 6.8k (R1). So if you are building a new SDS cap board check the bleeders before installation. I'll see what Triode will do, because when I received the kit it was missing the 22k (R2). I called triode to order more parts and they said we'll ship the resistor with your order. When the order arrived guess what no 22k Yellow_Light_Colorz_PDT_21 . Oh well.

Now (impatiently) on to the spare parts box.......

Ted

Matt from Triode just sent an email stating that they found and corrected the mixup. Matt also said they would replace the board and correct any damage to the amp.

Holy cow! I just checked my board and the bleeders are marked 3320, so I guess i'm ok? I'm new at this but I guess that would make them 332k.

Hi All,

That number code is a military version of the color code. For a 1% resistor, the first three digits are the significant figures of the resistance (in this case, 332) and the fourth digit is the power of 10 the first three need to be multiplied by (in this case 10° = 1). Thus, 332 * 1 = 332Ω.

The same code is used on 5 and 10% resistors (only 2 SFs instead of 3) as well as some ceramic and poly caps. Generally, if the capacity unit (pF, µF, etc) is NOT indicated, the above code is in effect and the value is expressed in pF, but not always. If you have a cap whose third digit is a 0, such as 220, you can't tell if it's 220 pF or 22 * 10° pf--an order of magnitude. Most modern DMMs have capacitance ranges; when in doubt, measure.

GRRRRR!!!!!

Thanks for the info guy's. Just got a warning email from Matt at triode. I bet the new parts bin stocker is in big trouble!

They should be marked 3323 (332,000); 3320 will be 332 ohms.

Got another email from Matt yesterday. He is ordering new parts next day air and sending them out.

My issue is I bought the board preassembled due to no experience soldering those smt componets. I'm also rough on desoldering. I haven't heard back as to how this will be handled. Ya think someone here could talk me through it?

Wmacky,
I bought the bare SDS board and assembled it myself but I have quite a few years of soldering experience. If you were amywhere in the Southern California area I could do it for you. If you have to do it yourself, here are my suggestions.
You will need a good quality solder wick around 1/8 inch wide. Solder wick is finely woven copper wire that has been prefluxed.
You will need a good quality soldering iron of about 25-35 watts with a chisel tip approx 1/16 inch wide.
You should also have a tube or bottle of electronic flux.
The key to soldering is to have a clean tip at the proper temperature. If the tip constantly discolors after cleaning, the temperature is probably too high and you will have mucho trouble. I use a tip cleaner that is a pad of brass wool in a weighted holder. But a piece of an old towel slightly moistened slightly or a soldering sponge will work also. They shouldn't be soaking wet just moist. Wet will cool the iron too much and the solder won't wipe away. Always clean the tip immediately before soldering. Wipe tip, apply some solder with a flux core to the tip then wipe again. You cannot solder with a dirty tip or one that is too hot. It will oxidize rapidly and will not transfer any heat to the part being soldered.
OK, that being said, to remove the old SMT resistors, place a small dab of flux on each soldered joint. Then position the solder wick flat on the PCB solder pad right next to one end of the SMT. Clean the iron and place the flat of the tip onto the solder wick so that the soldered joint melts and flows into the wick. Keep fingers a few inches back as the wick IS copepr and conducts heat well. Move the wick/iron tip around a bit to suck up as much solder as possible. Cut the used part of the wick off with wire clippers as it fills up with solder. Do this to both ends and soon the SMT will come off. Once the SMT is off use the flux and wick to remove as much solder off the pad as possible, wipe the pads clean with a moist cloth and let the PCB cool.
When they are all removed, apply some flux to the PCB pads and a bit to the new SMT resistor ends where they are silvered. One at a time, position a resistor so that the silvered ends are equally spaced on the PCB pads. The flux will help hold it in place. Clean the iron and place a small ball of solder on the tip. Use a small wooden stick like a Q-Tip with the end cut off to hold the SMT and apply the iron tip with the solder ball to one SMT end. The tip should touch BOTH the pad and the SMT end. The solder should flow quickly between the pad and the SMT end. Remove the iron and blow on the joint while still keeping it in place with the stick.
This should solder one end. Repeat the process on the other end IF the SMT is correctly positioned. If the SMT moves while the solder is still molten, clean the tip and apply the iron to the joint to melt the solder while repositioning it with the stick. Don't solder the other end until the SMT is positioned correctly. Don't apply heat to the other end too long so that the first end melts or the SMT will slip-slide away and you will have to start over.
Remember, the key is having a clean iron tip that is not so hot that it oxidizes rapidly. A temperature controlled iron is great but a bit pricey. A good pencil iron and a variac will also work. The tip should be hot enough to melt the solder but not so hot that it discolors in less that 5 to 10 seconds.
Good Luck
Mike

Thanks! thats great info. I might try this rather than ship it back! BTW I have a Hakko 936 with a selection of tips, braid, and a sucker enroute to me! I did not order flux. Can I get this at the shack? The hakko has temp adjust. Could you tell me the proper temp for the procedure you posted?

Hi All,

Mike's advice is excellent, although I prefer toothpicks over Q-Tips for positioning and holding components while soldering. Some additional info you might or might not wish to use . . .

Electronic Goldmine www.goldmine-elec.com has several learn-to-solder kits, including a couple of SMD kits. The prices are reasonable, and the chance of messing up the "real thing" would be lessened by practicing on non-critical components. I'm an old fart in this industry and I bought one to become more adept at SMT when it became obvious that it wasn't going away.

Radio Shack sells a rosin paste flux which I can't really recommend for surface mount work because of its viscosity. If you have a decent music store nearby, pick up a bar of violin rosin. Then find a decent drug store and ask the pharmacist for a bottle of anhydrous isopropyl alcohol--they normally don't stock it on the shelves. DON'T use rubbing alcohol; use denatured alcohol only if you can't find the isopropanol.

The rosin dissolves readily in the alcohol, so you can take a #1 or 2 artist's brush, dip it in the alcohol, rub it on the rosin, and brush the solution on the connections that need it. You can also grind or shave it and mix it with the alcohol in a small bottle so it's ready to use when needed.

After the surgery's been performed, use the alcohol to remove the flux remaining on the board with a flux brush available at hardware stores for about a quarter. I like to trim the bristles to about 5/16~3/8" to get a little stiffness in them.

Keep us informed on your unintended adventure.

Warning:
Here's a lazy man, I-don't-have-any-flux and just one iron method.

I would solder the ends of the current resistor with more solder, as the extra solder plus any rosin helps distribute the heat like flux. Then I crank up the iron to 750+ degrees and start heating up one side then quickly go to the other. After about four quick hops the part will flop off. Wick off the extra solder on one pad. Use tweezers to place the new resistor, heating up the glob of old solder you left. Then solder the other side. One minute job. You can wick any extra solder at this point.

Shannon

I just built a couple of SDS boards for my Poseidon amps - where are there any Surface Mount Devices ?

TomMcNally wrote:I just built a couple of SDS boards for my Poseidon amps - where are there any Surface Mount Devices ?

Hi Tom,

Flip it over. Yellow_Light_Colorz_PDT_16

They are snuck in-between the snap mount cap leads.

Shannon

Oh ok - apparently only in the pre-assembled version. Or at least not in the MK-III version which is what I have.