Author Topic: KEITHLEY 228/228A  (Read 7834 times)

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Offline Inverted18650Topic starter

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KEITHLEY 228/228A
« on: March 16, 2018, 10:00:07 pm »
This thread will be my repository for my Keithley 228 and Keithley 228A source meter. The first section of this thread is going to look at reproducing the PCB for the input section. Photos "A - S" are of the PCB that is being used to recreate the board. I have started the project in EasyEda and it is "public" so anyone can view, copy, and get them made on their own. The current version, V1, was done in hast and I half-assed it by not designing in the original screw-terminals (thank you bitseeker for parts links and calling it to my attention). I will finish the board shortly and post the link here along with the screw terminals parts links.

If I missed anything in the pics below, please let me know and I will fix it.  If you have one of these units and my PCB is different than yours, please share pics as well.

In the next section of the thread, I will post complete tear down pics and compare the 228 and the 228A side-by-side.
« Last Edit: March 16, 2018, 10:01:52 pm by Inverted18650 »
 
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Offline Inverted18650Topic starter

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Re: KEITHLEY 228/228A
« Reply #1 on: March 16, 2018, 10:03:18 pm »
K-S (forgot about J)
 
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Offline Inverted18650Topic starter

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Re: KEITHLEY 228/228A
« Reply #2 on: March 17, 2018, 05:54:20 pm »
The screw terminals for the PCB are here: https://www.mouser.com/ProductDetail/534-1201. (thanks again to bitseeker).

I checked the datasheet and used my (cheap) caliper to verify the dimensions: https://www.mouser.com/ds/2/215/201-741482.pdf

I ordered 80 terminals to built the 10 PCBs.
 
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Offline Inverted18650Topic starter

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Re: KEITHLEY 228/228A
« Reply #3 on: March 17, 2018, 06:44:46 pm »
The EasyEda project is here: https://easyeda.com/the18650movement/K228_INPUT. I think I have everything correct. Be sure to check the "attachments" tab for pics and info as well. Because EasyEda automatically generates the solder mask layer, I did not add it to the project. You can click the "Photo View" (camera icon) at the top of the page, you can see a rendering of the finished product. The gerber files are attached in the .zip. Thanks again to Peter for all the help.

Offline bitseeker

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Re: KEITHLEY 228/228A
« Reply #4 on: March 17, 2018, 07:15:12 pm »
Thanks for consolidating everything into the thread. Looking good! It'll be interesting to see if there are any differences between your 228A and mine. I still have to get some new configuration RAM batteries for mine.

Because EasyEda automatically generates the solder mask layer, I did not add it to the project.

How do they know where the card edge area is in order not to solder mask it (and apply the gold fingers)? Do you have to add a rectangle to define it?
« Last Edit: March 17, 2018, 07:17:39 pm by bitseeker »
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Offline Inverted18650Topic starter

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Re: KEITHLEY 228/228A
« Reply #5 on: March 17, 2018, 09:27:19 pm »
I used 'pads' for the all the fingers instead of the 'solid area' feature. The 'pads' tool leaves the copper exposed. At checkout, I selected "gold fingers without chamfer." Even though it looked good in the gerber viewer, I probably should go back and add a documents layer to identify the card edge and all the nets that will get the gold layer just to be safe. I will do that now and post Gerber_V3 in a moment.
 
edit:
Glad you asked, because I never edited the 'V1' documents layer, which may have caused them confusion...many thanks! I added the notes on the documents layer and in the remarks section of the order form I wrote: "The document layer contains detailed information about the GOLD FINGERS and the CARD EDGE of this PCB." This is my first card edge board so we will see how it turns out and if I need to make corrections, no worries, they get them to me super fast. Total is $2 for 10 boards and that's with the gold fingers added. V3 attached.
« Last Edit: March 17, 2018, 10:02:00 pm by Inverted18650 »
 
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Offline bitseeker

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Re: KEITHLEY 228/228A
« Reply #6 on: March 17, 2018, 09:45:44 pm »
I see. This is my first experience with EasyEDA, so I wasn't sure what's the right way to go about it.
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Offline Inverted18650Topic starter

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Re: KEITHLEY 228/228A
« Reply #7 on: March 17, 2018, 10:05:40 pm »
They provide a nice little Gerber Viewer tool as well. Just drag and drop the .zip

https://gerber-viewer.easyeda.com/

I attached pics from the viewer.

Offline bitseeker

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Re: KEITHLEY 228/228A
« Reply #8 on: March 17, 2018, 10:18:54 pm »
Oh, cool. Well, it looks good to me. If anyone else sees anything that needs fixing, speak now. ;D
« Last Edit: March 17, 2018, 10:26:34 pm by bitseeker »
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Offline Inverted18650Topic starter

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Re: KEITHLEY 228/228A
« Reply #9 on: March 18, 2018, 04:54:48 pm »
I made a few more changes:

1.) I was using the "track tool" for the traces from the card edge to the screw post terminals and it gave them the rounded, oblong look, which I didn't like. I went back and used the "solid area tool" and laid the two large tracks coming from the 'OUT +' & 'OUT - ' pads on the bottom of the board. It gave it a cleaner, squared up look.

2.) I also changed 'IMON -' & 'IMON + ' to better match the angles of the traces on the OEM board. (may not matter but I did it anyway).

3.) The fingers for the card edge are 6.5mm long, not 7.0mm.

After I made these changes, I sent it over to the board house. I will shoot some footage when the PCBs arrive. Gerber V4 & pic Bottom_V2 attached.

Offline bitseeker

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Re: KEITHLEY 228/228A
« Reply #10 on: March 19, 2018, 03:03:47 am »
Thanks for the updates. I wasn't a fan of the wide, rounded traces either, but I didn't want to nitpick since it was purely aesthetic. This version does look a lot better. A very nice replica it is.

Now that it's off to manufacturing, there are some things about the original board layout that puzzled me.

Why does the original have somewhat rounded ends on the main output traces near the sense screw terminals? At first I was thinking it might be for additional creepage distance between output and sense. However, on the back side, the output and sense traces are even closer together.

I also found it odd that the sense and monitor terminals have additional traces joining the pads around the slots instead of simply using larger center pads to join them them all together, like on the output terminals.
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Offline Inverted18650Topic starter

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Re: KEITHLEY 228/228A
« Reply #11 on: March 23, 2018, 01:33:59 pm »
Peter, those are great questions, but someone smarter than me will have to answer them. I was wondering the same thing. Where are the PCB layout wizards?

update: the screw terminals arrived and are a perfect match (thank you Sir!) BUT there was an issue with the PCB. The factory replied stating that I cannot have get JUST gold fingers on the PCB. I must choose the 'ENIG' option at checkout and have the entire board gold plated ( even though they allow you to use the default HASL and select gold fingers for free). I wasted a week trying to sort out the issue with their customer support.

I know this is my fault for not already knowing the difference between the two processing options but I was a bit upset that it took a week to sort out. Don't let this happen to you. I have asked the factory to cancel my original order and sent over another request with the correct ENIG processing. The entire board will be gold plated and it will cost $2 per board ($20 plus shipping) instead of $2 for all 10. No worries, happy days.

Offline bitseeker

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Re: KEITHLEY 228/228A
« Reply #12 on: March 23, 2018, 06:38:03 pm »
someone smarter than me will have to answer them. I was wondering the same thing. Where are the PCB layout wizards?

Oh, it was a general question, in case someone knew. Perhaps "PCB" in the thread title would provide the requisite click bait (so to speak), but that would restrict the topic breadth you originally intended.

Quote
The factory replied stating that I cannot have get JUST gold fingers on the PCB. I must choose the 'ENIG' option at checkout and have the entire board gold plated ( even though they allow you to use the default HASL and select gold fingers for free). I wasted a week trying to sort out the issue with their customer support.

So, what was it about the board that triggered the requirement to go ENIG? Was it the large output traces (i.e., not your typical fingers)?

Quote
The entire board will be gold plated and it will cost $2 per board ($20 plus shipping) instead of $2 for all 10. No worries, happy days.

That's not so bad. I'm not sure if you can still get the boards from Tek/Keithley, but it'd probably cost quite a bit more even after adding in the screw terminals, shipping, etc.
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Offline Inverted18650Topic starter

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Re: KEITHLEY 228/228A
« Reply #13 on: April 02, 2018, 06:16:02 pm »
Brief update due to time constraints:

The PCBS arrived today. I quickly checked the design to ensure the boards were the same size, shape, and the screw holes were correct. I have two sets. One set is the 'HASL- with Lead' and the other is 'ENIG-RoHS, with Gold Plating'. Screw post terminals fit well.

Here are a few pictures. Much more detail plus assembly & test coming soon.

Offline bitseeker

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Re: KEITHLEY 228/228A
« Reply #14 on: April 02, 2018, 06:31:37 pm »
Looking good! :-+
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Offline LapTop006

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Re: KEITHLEY 228/228A
« Reply #15 on: August 23, 2018, 04:58:26 am »
The first section of this thread is going to look at reproducing the PCB for the input section. Photos "A - S" are of the PCB that is being used to recreate the board.

It's a shame I didn't notice this when it was posted, I picked up a 228 last year and also recreated an output board, I should upload my KiCad files somewhere. They're nice units, although the UX is a bit of a pain.
 

Offline bitseeker

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Re: KEITHLEY 228/228A
« Reply #16 on: August 23, 2018, 05:31:11 am »
KiCAD files can be imported into a project on EasyEDA, where we did the board discussed in this thread.

https://docs.easyeda.com/en/Import/Import-KiCAD/index.html

Otherwise, you can put them on GitHub or similar.
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Offline Ordinaryman1971

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Re: KEITHLEY 228/228A
« Reply #17 on: November 08, 2018, 05:03:58 pm »
I would need three of those boards... anybody has some that were build but never used maybe?
 
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Offline bitseeker

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Re: KEITHLEY 228/228A
« Reply #18 on: November 08, 2018, 11:56:17 pm »
Ordinaryman, stand by. I will check later tonight. PM sent.
« Last Edit: November 09, 2018, 02:37:38 am by bitseeker »
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Offline LapTop006

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Re: KEITHLEY 228/228A
« Reply #19 on: November 09, 2018, 07:22:53 am »
If bitseeker doesn't, I have spares of mine, but easier is likely share gerbers and get your own boards made, it's probably cheaper than shipping from Australia.
 

Offline bitseeker

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Re: KEITHLEY 228/228A
« Reply #20 on: November 09, 2018, 07:24:07 pm »
No worries, LapTop006. I got Ordinaryman covered. Thanks for offering to help out. It's one of the many great things about the EEVblog forum/community.

How do you connect wires to your board? Solder them directly to the pads?
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Offline LapTop006

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Re: KEITHLEY 228/228A
« Reply #21 on: November 09, 2018, 07:46:52 pm »
How do you connect wires to your board? Solder them directly to the pads?

Yep, straight onto the pads, they way I don't need to worry about the small clearance below the board.

The mechanical holes were done so I can use cable ties for physical retention.
 

Offline bitseeker

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Re: KEITHLEY 228/228A
« Reply #22 on: November 09, 2018, 07:52:18 pm »
Ah, I was about to ask about those holes, next.  ;D
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Offline Inverted18650Topic starter

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Re: KEITHLEY 228/228A
« Reply #23 on: December 23, 2018, 12:27:28 am »
Hello all, I am back on the forum and if anyone needs any of these units I have about 12 left. Some are the silver before I figured out how to use the gold finger outline in easyeda. I also have the screw posts, but not the small shorting links for the sense wires; i just cut and drilled so old sheet cooper for those. Reply or message me if you want any, just cover shipping.

Offline cncjerry

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Re: KEITHLEY 228/228A
« Reply #24 on: December 23, 2018, 02:09:27 am »
Just found your thread.  I have an actual input board though I doubt that helps now.   It has a clamp on the back making it easier to pull out.

I use my 228 for a lot of things, though mostly for charging batteries these days and you can program it to drain the battery then bring it back up at varying current rates.

I'll take a couple of boards and will send you a PM.

thanks!

Jerry
 


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