Yet another resistance decade box

[Back2Volts]

Fortran , just sent payment for one 0.1% set

Tony

[Fortran]

No worries. You're on the pre-order list
I'll send it as soon as the resistors arrive.


Btw.. has anyone from the first run not gotten theirs yet?

[ebclr]

Could you please confirm the shipment of my boards

[Fortran]

Sure.
Send me a PM with your name and/or adress and I'll check.
I can't find an order here on the forum so I can't connect your username to a shipment

[Back2Volts]

Just sent Paypal for the two additional

[ez24]

Just got mine in So Calif.  Got the boards out of the switches.  Now to see if I can solder SMDs

[Fortran]

Could you please confirm the shipment of my boards

After some digging I finally found which order is yours, and yes. It was shipped on July 13'th.
It should have arrived by now. Maybe it got stuck in customs?

If it doesn't turn up soon I'll send you another.

[cucumbers]

My kits have arrived in Australia. Look very nice, now I just need to get a few sets of the right sized thumbwheels. Cheers Fortran! 

[ez24]

maybe a version for through hole resistors (higher wattage?) would be a good idea?

Yes thanks - good for senior citizens

[johnmx]

Got my switches today. Tomorrow I'll assemble the kit and show some pictures.

[ez24]

whew

Just did my first board.  First time with these really small SMDs.  Like training fleas.

It is a really bad job.  The resistors are sticking up at all angles so no pics.    

I snapped in the board with no problems and it holds strong.  Checked with a meter and it works 

Just curious there are 10 resistors.  Is the 10th resistor an extra?   I think I am counting right??   I just have tweezers and a cheap 25w iron and reading glasses.  No fancy stations.

Shaking now so I will have to wait until tomorrow and try another one.  I started with the 100k set.

I would like to know if I need to tin the pads fist before I try another one.  Tinning the pads makes the resistors not lay flat.  How about tinning one pad so the solder makes it stick flat, by pushing down with the tweezers while soldering, then solder the other end without tinning it?

Going to order another set of switches tonight.

Good job, how many people worked on this job?  Thanks Fortran

thanks

[LeonV]

Got the boards + resistors yesterday   

All the way in New Zealand.

Now to buy the pushwheels..
Will try these:
http://www.aliexpress.com/item/Black-18mm-x-6mm-0-9-Digits-BCD-Code-Pushwheel-Thumbwheel-Switches-KM2/1804257049.html

But will need to save up, so wont be too soon.

[Fortran]

Just curious there are 10 resistors.  Is the 10th resistor an extra?

Yes the 10th resistor is extra. In case you flick one off the table
The 0.1% strips are only 9 though, because of the much higher price.

Tinning one pad and sticking down the resistor before soldering the other pad is a very good way to do it.
Using only an iron you might want to use as little solder as possible just to make it stick, then come back after soldering the other side and just touch it up with some fresh solder to make it flow nicely.
Heating too long makes the joint lumpy and ugly.
If you're ordering another set, let me know if you want me to solder it for you.

Two people worked on this.
PeterZ drew the board and posted the design files, and I ordered them in enough quantity to make them affordable for everyone.

[ez24]

Tried another board by tinning one contact.  Had a 7 out of 9 failure rate.  I could be only the "3" digit, in other words only 1 and 2 work.
My 4 power glasses are not powerful enough so I cannot see if I have a cold joint nor do I know which one is the third digit.

Also the board would not snap in, is was too wide.  I solved this by making a very small bevel with a razor blade and it snapped in.  So for now on I am going to make a small bevel on the switch and on one side of the circuit board.

It might be possible to do one contact at a time if I had a small tip and solder.  It is very hard to get in to solder (the ends) with the large (used to be small, I think 1/8") iron that I have.  So I will go back to tinning both pads first and put up with tilting resistors.  If it is good enough for the Italians it should be good enough for me.

Also it is good to have an extra resistor.  One stuck to my iron and dropped as I moved the iron.  These things are so small they evaporate as they fall through the air.

Has anyone come up with a trouble shooting guide using via to via resistance readings?  I cannot see the traces.  In other words how can I find No. 3.  I am wondering if there is a No. 3 ?  I wonder if it depends on how the switch goes together.  In other words maybe 3 one time but 5 the next time??


thanks

[Fortran]

You shouldn't need to trim anything to make it fit the switch, but I guess there may be slight variations in batches.
I found that pressing down firmly right next to the pilot holes using a 5mm wide flathead screwdriver worked really well.
If it still won't cooperate you can try sanding the edges a bit.

Attaching a layout of the board.
If you have problems with No. 3, you probably have a solder-bridge to the via that goes underneath it.
Check if it's shorted.

[garnix]

Will try these:
http://www.aliexpress.com/item/Black-18mm-x-6mm-0-9-Digits-BCD-Code-Pushwheel-Thumbwheel-Switches-KM2/1804257049.html

I got those as well - seem to work. Just be aware that there are no end-caps.

BTW, is there a seller who sells end-caps for those wheel switches?

[all_repair]

Thank you Fortran.  Got my 6 sets of PCB and 5 sets of resistor kits.  I felt bad that you must have taken so much time to pack them so nicely.  And thank you Peter for the PCB work.
I have used an electrical conduit plastic as the enclosure.

[ez24]

If you have problems with No. 3, you probably have a solder-bridge to the via that goes underneath it.
Check if it's shorted.

I spotted that one of the vias under 3 had solder in it.  I bought 6 sets for 2 set of switches, so now I am down to 5.  I cannot fix it.

I pre-tinned my next board and was very careful of the vias and did a decent job of soldering BUT 100 % failure.  Did some random continuity checks plus I found a 10x magnifying glass and everything looked ok.  Was about to give up when I thought the "fingers" could be the problem.

I bent up the fingers and it worked, every range OK.  Now I have two boards done 

Getting experience with these SMDs.  My feeling is god did not intend for humans to use these things.  Tomorrow I am going to try #3 (1k)   

Once again I want to say thanks to everyone that put this project together, and especially to Fortran for selling the kits.  I am thrilled at 68 I can solder the damn things. (and see them)

I will admit I am not clear how I wire the switches together (series ?).  I think so far there is only one picture and I do not get it.  I hope people will start posting pictures so I can figure it out.

Again I really appreciate the work of the members who put this together, I am having fun.

[johnmx]

As promised here are the photos.

ez24, you can see the connections in my pictures.
An easy way is to use two long rigid wires. Put all switches together and insert the wires through all switches.
Now solder all the pads except the two pads where the external wires go. After that just cut the wire according to the picture.

[ez24]

As promised here are the photos.

Thanks
Your soldering sure puts mine to shame 
Just curious - what soldering set up do you have?  Do you pre-tin the pads?

[johnmx]

Just curious - what soldering set up do you have?  Do you pre-tin the pads?

I have this soldering station:
http://www.jbctools.com/cd-2bc-soldering-station-for-general-purposes-product-710-category-1.html

It can heat up in less than 2 s. It's amazing.
More about this:
http://www.jbctools.com/heating-system.html

And I use this microscope:
http://www.optikamicroscopes.com/index.php?option=com_virtuemart&view=productdetails&virtuemart_product_id=254&virtuemart_category_id=5&lang=en

I do soldering since 12 years old. So I have a lot of experience in this matter.
I can get the same results with a normal soldering iron and no microscope with SMDs down to 0805.
With the microscope I can solder very well 0402 components.

About the soldering, there are several videos in the internet, but some are completely wrong. So be carefully.
What I do is the following:
- Put some solder in one pad of each footprint. Don’t put too much, it’s better to have little less than too much. Do this for all footprints.
- Now pick up the component with a good tweezer using your left hand (if you are right-handed). Place it over the footprint without releasing the component. This insures that the tip of the tweezer is higher than the bottom part of the component. If you release it, just make sure about this when you hold it again.
- Now with the component in place, heat the pre-soldered pad with the iron and press down the component while the solder is liquid.
- Remove the iron, wait some seconds. Could be 2, 3 or 5 s, it depends on how much heat you applied to the pad.
- Release the component by opening the tweezer.
- Put the tweezer on the table and hold the soldering wire (solder) with your left hand.
- Solder the other(s) pad(s) of the component.
 - If the first pad was not very well soldered, you can put a little more solder on it.
That’s it.
Some tips:
-   Don’t use “Free Lead Solder”. It’s much harder with this new type of solder.
-   Apply some flux to the pads if the solder is not fixing well to the pad or to the component. I prefer liquid flux and apply it with a small brush. I buy the flux in big bottles and put it in an old nail polish container (see the attached picture).

[gblades]

Normally I would tin one pad and then pick up the resistor with tweezers and melt the solder on the pad again and move the resistor into position. Then solder the other end. Apply some flux to the 1st joint and touch it with the soldering iron to reflow it.

However when I assembled mine I dabbed a little solder paste on the pads and stuck down the resistors and then flowed the solder using a hot air gun. I did that mainly for practice and it generally worked well apart from putting too much paste on the first board and getting a short under one of the resistors. Easy to remove with a hot air gun though.

I use a jewellers headband with a built in light and different magnification lenses that you can clip in. It works and preserves your depth perception so way better than the 'helping hands' with a built in magnifier but still a poor comparison to a proper microscope but then again they are a lot cheaper!

[ez24]

What I do is the following:
- Put some solder in one pad of each footprint. Don’t put too much, it’s better to have little less than too much. Do this for all footprints.
- Now pick up the component with a good tweezer using your left hand (if you are right-handed). Place it over the footprint without releasing the component. This insures that the tip of the tweezer is higher than the bottom part of the component. If you release it, just make sure about this when you hold it again.
- Now with the component in place, heat the pre-soldered pad with the iron and press down the component while the solder is liquid.
- Remove the iron, wait some seconds. Could be 2, 3 or 5 s, it depends on how much heat you applied to the pad.
- Release the component by opening the tweezer.
- Put the tweezer on the table and hold the soldering wire (solder) with your left hand.
- Solder the other(s) pad(s) of the component.
 - If the first pad was not very well soldered, you can put a little more solder on it.
That’s it.

This is what I did on the last one, and it works great 
Nice to know I am doing it right

A fast heating iron is high on my list, my biggest fear is I will forgot that I plugged in my iron because it is so slow, I usually get distracted.  I try and set the timer on my phone (if I can remember) 

 

Thanks

[ez24]

.. and getting a short under one of the resistors. Easy to remove with a hot air gun though.

I use a jewellers headband

I am going to save my "bad" boards just in case someday I get a hot air gun.

I found my jewelers headband, this is how I determined that board #2 had solder in the via and #3 was ok (the switch was bad)

[smgvbest]

In the FWIW area on soldering
I use one of these
https://www.circuitspecialists.com/Hot-Air-Soldering-Station-Power-Station-Plus.html

and one of these to apply solder paste
https://www.tindie.com/products/marjan_mike/electronic-solder-paste-dispenser-v5-air-freeair-/

the use the the hot air gun set to the reflow temp of the solder and move it back and forth over the boards.
done in no time.