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Good morning Group,
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Hoping for information and validation of a proposed repair for a problem I created while assembling my new QMX kit.
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I cracked SMD 0603 capacitor C513 (its in the TXBias input area of the Low Pass Filters section).
It looks like a typical by-pass capacitor to me, BUT I am not an EE or talented RF designer.
I was able to float it off and cleaned up the solder pads.
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I wanted to see if anyone could give me the basic specs (tolerance and V rating)
AND . . .
Get opinions/advice on whether I could replace that component with a small, regular 0.1uf ceramic capacitor with lead wires. I ordered a 10 pack from AdaFruit of common, 0.1uf bypass capacitors (+/- 20% - 50V), I'd preform the leads, insulate with quality shrink tubing, tape the component down and then tack and solder the leads to the pads. Figured I'd add a drop of hot glue to the 'face' of the component to make sure it stays flat on the board during the rest of the kit assembly, and getting everything in the enclosure.?
I'm almost certain I can solder the leaded component onto the pads and have it lay flat in a nearby empty area, rising above the board at no more than 2 - 2.5 mm.
I'm not so sure I can successfully solder in a replacement? 0603.? 74 year old eyes, hands and fingers aren't what they used to be. I do have a good soldering irons and a magnifying headlamp (up to 15X) and can still assemble, modify and repair tiny through-hole component 'stuff' pretty well.?
All info, opinions and suggestions are welcome.
73?
Greg - KI4NVX
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On 06/03/2024 14:21, Greg McCain via groups.io wrote: I'm not so sure I can successfully solder in a replacement? 0603 Greg, All you need is a 0603 0.1uF from a reputable dealer. Liquid flux, a clean fine iron and suitable vision. I use ordinary x4 reading glasses.Hold it in place, (most difficult part?) A dob with the iron should attach it to the pre-soldered pad. I can give you 7 years. Best if you got an old board and tried a few times. Thinking about the job is good, worrying bad:-) 73 Alan G4ZFQ
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Alan and Evan,
Great info and good advice.
I've got a 10 pack of SMDs coming from DigiKey now too. Have looked at a few SMD soldering videos and will give that a try first. Fortunately that cap is in a relatively open area :)
I agree, thinking things through is always better.
Very impressed with QRP-Labs kits, assembly instructions, the great on-going support from Hans and the gang and of course this great Group.
My first serious kit build was an Elecraft K2 about 18 years ago, with all the Un-Un additions and almost every option they offered at the time. (about 100 man hours of prep and work !) Have recently assembled 3 of the 50W amp kits, figuring out turns and capacitor values for one on 15 meters that works very well. Don't plan on running any of the three ( 40, 20 15) at more than 10amps for FT8, WSPR, and JS8Call, and then only when conditions are crappy and I need the extra punch. My basic bench testing into dummy loads showed no issues and on-air testing with the K2 and the QRP-Labs amps was FB.?
I'd say QRP-Labs are every bit as good as the big E.?
73 Greg KI4NVX
On Wednesday, March 6, 2024 at 09:50:56 AM EST, Alan G4ZFQ <alan4alan@...> wrote:
On 06/03/2024 14:21, Greg McCain via groups.io wrote:
> I'm not so sure I can successfully solder in a replacement? 0603
Greg,
All you need is a 0603 0.1uF from a reputable dealer.
Liquid flux, a clean fine iron and suitable vision. I use ordinary x4
reading glasses.Hold it in place, (most difficult part?)
A dob with the iron should attach it to the pre-soldered pad.
I can give you 7 years. Best if you got an old board and tried a few
times.? Thinking about the job is good, worrying bad:-)
73 Alan G4ZFQ
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Hi,
I’ve found that a wooden cocktail stick works well for placing and holding tiny smd caps etc. Just a little touch of glue on the end. I use “Prit Stick”, which is a lip balm dispenser type used for kids paper modelling etc, but just about anything a bit sticky will do. Not anything permanent like superglue!!
73.
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I use Blue Tac to hold components in place before soldering.??
I cannot keep smd parts in place with a tooth pick.
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I use a solder paste dispenser for larger jobs, primarily because it can also be used as a pick-and-place device. It doesn't have an expensive compressor, instead it relies on stepper motors and air pistons for pressure and suction. You can get the unit with an accessory pick-and-place stylus, that comes with a set of small, soft tips for various sizes of components. You CAN use the main unit for pick-and-place, but it's larger and less maneuverable, which can lead to fatigue. The separate stylus unit is VERY lightweight and maneuverable. With this system, you get the benefit of solder paste extrusion AND pick-and-place. It will also dispense flux, adhesives, and other viscous liquids.
For a single component, I'd use a chopstick with a small bit of Museum Wax on the tip. A cheap bamboo disposable chopstick, like those you can get from a Chinese restaurant, can be whittled with a knife to a smaller point, or simply sharpened in a pencil sharpener. I use a long-point pencil sharpener for putting long, sharp points on drawing pencils, and I use that. But whittling is just as easy and cheaper. Museum Wax is great stuff to have around anyway -- it's typically used to secure small, valuable, and fragile objects on the shelves of museums, to keep them from falling when the shelf is nudged, or even when an earthquake hits, as an item stuck down with it is held securely enough that an earthquake would have to be so powerful that the museum itself might be in danger of collapse before things held with it might vibrate off the shelves. (The company name is "Quakehold", btw) I use it on key feet to keep the key from skittering off the table.
Museum Wax 2 oz container:?
-=-=-=-=-=-=-=-=- 73, Gwen, NG3P
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SUCCESS !!
DigiKey came through really quick.
I experimented with BliueTak and found it good for 'picking up'? the tiny bugger and not having it fall off when moving it to the PCB? . . . but . .
my attempt to use a tiny dab of Blue Tack to hold the cap down on the board between the pads didn't really work out well. The space was so small? and heat transferred quickly when attempting to solder that the tack just softened and the bugger moved around in a blue slurry. Cleaned up everything and started over.?
Ended up just getting mentally ready, donned a magnifying head lamp I bought (cheap but surprisingly good from Harbor Freight), used a small gripper tweezer and was able to tack solder one end.
Then full soldered the other side, let everything cool and final-soldered the first end.
It looks a bit wonky but .. . . . there is good continuity between each PCB pad and the top of the metal end caps on the component.
Definitely not shorted either . . .? so one in the win column???
Greg? ?KI4NVX
P.S. Pulled another bone head mental break and ended up destroying the BNC connector. Long story ...? Complete Operator Error.
Thought I'd created a short underneath the connector housing. Brain was thinking Power Connector and there wasn't any way I was going forward if I had managed to short the main power input.
Don't have a lab grade vacuum solder removing station and the metal shell and 4 big connections to the PCB ground plane just sucked up the heat. So ended up cutting it out and then clearing up the PCB after.?
DOH . . .? not the Power IN . . .? RF IN/OUT
Just placed an order for a couple of spares.
73?
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. My method is to lightly tin one side of the pad, maybe very lightly tin one side of the part.? Apply heat to the tinned pad, slide the part into place, a bit more heat, align as best?as possible.? Solder the opposite side, then go back and touch up the first.? ?Curved nose tweezers help a lot.?
If it’s a little crooked or not laying perfectly flat no worries.?
Larry KB3CUF?
On Sat, Mar 9, 2024 at 12:57?AM Greg McCain via <gamccain50= [email protected]> wrote: SUCCESS !!
DigiKey came through really quick.
I experimented with BliueTak and found it good for 'picking up'? the tiny bugger and not having it fall off when moving it to the PCB? . . . but . .
my attempt to use a tiny dab of Blue Tack to hold the cap down on the board between the pads didn't really work out well. The space was so small? and heat transferred quickly when attempting to solder that the tack just softened and the bugger moved around in a blue slurry. Cleaned up everything and started over.?
Ended up just getting mentally ready, donned a magnifying head lamp I bought (cheap but surprisingly good from Harbor Freight), used a small gripper tweezer and was able to tack solder one end.
Then full soldered the other side, let everything cool and final-soldered the first end.
It looks a bit wonky but .. . . . there is good continuity between each PCB pad and the top of the metal end caps on the component.
Definitely not shorted either . . .? so one in the win column???
Greg? ?KI4NVX
P.S. Pulled another bone head mental break and ended up destroying the BNC connector. Long story ...? Complete Operator Error.
Thought I'd created a short underneath the connector housing. Brain was thinking Power Connector and there wasn't any way I was going forward if I had managed to short the main power input.
Don't have a lab grade vacuum solder removing station and the metal shell and 4 big connections to the PCB ground plane just sucked up the heat. So ended up cutting it out and then clearing up the PCB after.?
DOH . . .? not the Power IN . . .? RF IN/OUT
Just placed an order for a couple of spares.
73?
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Greg,
Were you doing g your building late at night? ?I have had the same issues when doing that…. Learned many years ago when tires (no matter how refreshing it is to be in my shack) that past 9 PM I am worthless when trying to follow and understand building instructions. ?My best time is early in the morning when I should be doing other obligations. ?
We live and sometimes learn.
Be the REASON someone smiles today.
Dave K8WPE
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On Mar 9, 2024, at 12:57?AM, Greg McCain via groups.io <gamccain50@...> wrote:
?SUCCESS !!
DigiKey came through really quick.
I experimented with BliueTak and found it good for 'picking up'? the tiny bugger and not having it fall off when moving it to the PCB? . . . but . .
my attempt to use a tiny dab of Blue Tack to hold the cap down on the board between the pads didn't really work out well. The space was so small? and heat transferred quickly when attempting to solder that the tack just softened and the bugger moved around in a blue slurry. Cleaned up everything and started over.?
Ended up just getting mentally ready, donned a magnifying head lamp I bought (cheap but surprisingly good from Harbor Freight), used a small gripper tweezer and was able to tack solder one end.
Then full soldered the other side, let everything cool and final-soldered the first end.
It looks a bit wonky but .. . . . there is good continuity between each PCB pad and the top of the metal end caps on the component.
Definitely not shorted either . . .? so one in the win column???
Greg? ?KI4NVX
P.S. Pulled another bone head mental break and ended up destroying the BNC connector. Long story ...? Complete Operator Error.
Thought I'd created a short underneath the connector housing. Brain was thinking Power Connector and there wasn't any way I was going forward if I had managed to short the main power input.
Don't have a lab grade vacuum solder removing station and the metal shell and 4 big connections to the PCB ground plane just sucked up the heat. So ended up cutting it out and then clearing up the PCB after.?
DOH . . .? not the Power IN . . .? RF IN/OUT
Just placed an order for a couple of spares.
73?
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On Sat, Mar 9, 2024 at 01:05 AM, Larry Acklin wrote:
?Curved nose tweezers help a lot.?
I style #7SA tweezers for these tasks.? They have long, thin, curved blades and, importantly, are non-magnetic stainless steel ("-SA").?? Most chip components have nickel barriers under the terminations and will stick annoyingly to magnetic tools. Using two fine-tipped irons will make installation, and especially removal, of chip components simpler. Good binocular magnification is also a great help. 73, Don N2VGU
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Great tip. No pun intended. I'll look those up right now ...
On Sat, Mar 9, 2024 at 7:56 AM, Donald S Brant Jr <dsbrantjr@...> wrote: On Sat, Mar 9, 2024 at 01:05 AM, Larry Acklin wrote:
?Curved nose tweezers help a lot.?
I style #7SA tweezers for these tasks.? They have long, thin, curved blades and, importantly, are non-magnetic stainless steel ("-SA").?? Most chip components have nickel barriers under the terminations and will stick annoyingly to magnetic tools. Using two fine-tipped irons will make installation, and especially removal, of chip components simpler. Good binocular magnification is also a great help. 73, Don N2VGU
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Gwen Patton
David Wilcox K8WPE
Donald S Brant Jr