BK precision 3011B tear down (56K warning)

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BK precision 3011B tear down (56K warning)

Postby hak8or » Sat Dec 31, 2011 3:09 pm

Hello everyone! I did not know that there might be an interest in the components of function generators, but thanks to the latest thread of a function generator tear down (birthday gifts to myself, sqkybeaver), I decided to join in on the fun!

I got this function generator off ebay for fifty dollars including shipping, and it arrived all working. If it was in spec or not I am not exactly sure, but on my scope it seemed well within operating condition.

So, here are some pictures! :D
Edit: woops, pictures were down, they should be up now!

Image
http://8486.a.hostable.me/pictures/BK_functiongen_teardown/P1250575.JPG
Here is what it looks like usually, just sitting on the scope.

Image
http://8486.a.hostable.me/pictures/BK_functiongen_teardown/P1250576.JPG
Close up!

Image
http://8486.a.hostable.me/pictures/BK_functiongen_teardown/P1250577.JPG
It does actually work, 20 Khz square waves look good on the scope.

Image
http://8486.a.hostable.me/pictures/BK_functiongen_teardown/P1250585.JPG
Bottom of the function generator.

Image
http://8486.a.hostable.me/pictures/BK_functiongen_teardown/P1250586.JPG
Back of the function generator.

Image
http://8486.a.hostable.me/pictures/BK_functiongen_teardown/P1250587.JPG
Inside top cover of the function generator, you can see the shielding that they used.

Image
http://8486.a.hostable.me/pictures/BK_functiongen_teardown/P1250586.JPG
Inside the bottom cover of the function generator, more shielding.

Image
http://8486.a.hostable.me/pictures/BK_functiongen_teardown/P1250594.JPG
Top of the PCB plus other pcb's

Image
http://8486.a.hostable.me/pictures/BK_functiongen_teardown/P1250596.JPG
Back of the PCB plus other pcb's

Image
http://8486.a.hostable.me/pictures/BK_functiongen_teardown/P1250590.JPG
It has the same "switch" for switching from 240v to 120v as sqkybeaver's function generator, it is really cool!

Image
http://8486.a.hostable.me/pictures/BK_functiongen_teardown/P1250593.JPG
They even have a fuse "modifier" thing for the different voltages!

Image
http://8486.a.hostable.me/pictures/BK_functiongen_teardown/P1250597.JPG
A fuse from one of the inputs or outputs, I forget which one it was.


More to come tomorrow or after tomorrow! :D
Last edited by hak8or on Sat Jan 07, 2012 1:47 am, edited 1 time in total.
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Re: BK precision 3011B tear down

Postby hak8or » Sun Jan 01, 2012 9:30 pm

Here is the rest of the post, as promised!

Image
http://8486.a.hostable.me/pictures/BK_functiongen_teardown/P1250598.JPG
Here is something interesting that I have never seen before! It is like a gird of sort, I highly doubt it is some sort of RF trick or something like that. Anyone has any input on this? :P

Image
http://8486.a.hostable.me/pictures/BK_functiongen_teardown/P1250600.JPG
Those are the coolest little heat sinks I have ever seen! They are for the 2N2905 PNP transistors on the board.

Image
http://8486.a.hostable.me/pictures/BK_functiongen_teardown/P1250601.JPG
The left is a PNP transistor (TIP32C) and the right is a 15V linear voltage regulator (LM7815), but that is not the reason I took the picture. Look at the middle pins on the packages, they have a little tube around the legs, anyone know why that is? Is it to prevent a short if something metallic fell near the legs, or something else?

Image
http://8486.a.hostable.me/pictures/BK_functiongen_teardown/P1250603.JPG
Picture to show of all the ic's. Anyone else love the quality of that soldering?

Image
http://8486.a.hostable.me/pictures/BK_functiongen_teardown/P1250604.JPG
More of the tubing in the 2nd picture above, anyone has any guesses?

Image
http://8486.a.hostable.me/pictures/BK_functiongen_teardown/P1250605.JPG
Here is one last shot of the function generator, showing you all the components. Funny thing, when the entire unit is assembled, the component side of the PCB faces DOWN, not up, first time I have ever seen something like that.

Hope you all enjoyed it! I am not doing much of a write up because I am just too tired right now, with new years and all. Hopefully all your new years are starting out well! :D
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Re: BK precision 3011B tear down

Postby sqkybeaver » Mon Jan 02, 2012 12:01 pm

the insides look incredible similar to the gw i just picked up.
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Re: BK precision 3011B tear down

Postby hak8or » Mon Jan 02, 2012 1:01 pm

Yeah! :P I wanted to post this up to show along side your pictures, that these function generators have similar designs.

I also just realized that I did not put up the pictures of the maximum frequency on my scope of this function generator.
Also, I forgot to mention that the rise and fall time on this guy are about 125 nS, and when operating at max frequency (2+mhz) the square wave and triangle wave all look like sine waves, what about yours?
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Re: BK precision 3011B tear down

Postby arakis » Wed Jan 04, 2012 3:13 am

I think the grid like pattern is a old ground filling technique...
best regards FIlip.
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Re: BK precision 3011B tear down

Postby hak8or » Wed Jan 04, 2012 2:52 pm

arakis wrote:I think the grid like pattern is a old ground filling technique...


Oh gosh, you are probably right about that. I remember from Altium that you can do ground fills in various ways, not just a simple plane, but I have never seen that in the wild. I would be presuming that such a ground fill would be used in special exotic cases, I don't see why someone would use a grid ground like that instead of a normal copper plane.

That just means more would have to be etched away when getting the board done, so I don't really see why they would do that, any ideas?

Some quick googling found me some good pdf's
http://www.ti.com/lit/an/szza009/szza009.pdf <-- mentions grid ground, but I am not sure if their version of "grid" is the same as what is in the picture
http://www.nxp.com/documents/applicatio ... N10897.pdf <-- same as above, I don't think their grid is same as in picture
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Re: BK precision 3011B tear down

Postby msr » Wed Jan 04, 2012 3:09 pm

This book describes the various options for ground planes giving also a somewhat historical background. Grid ground is not used nowadays at least for technical reasons. Arduino still use it, just to be "cool" I guess :)
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Re: BK precision 3011B tear down

Postby JanW » Wed Jan 04, 2012 5:18 pm

The whole thing is built from very basic integrated circuits, at least I have not seen a function generator IC or sine shaping network IC. Would be nice to study the schematics. Even the frequency counter is built of 4000 series logic. Nice instrument - you will never run out of spare parts :)

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Re: BK precision 3011B tear down

Postby hak8or » Wed Jan 04, 2012 11:13 pm

There are a few function generator ic's on the market, I never seen one in the wild before, but here are a few:
http://www.maxim-ic.com/datasheet/index.mvp/id/1257
http://www.intersil.com/products/device ... pn=ICL8038
One con to these guys is that I don't really expect them to be of much worth, they are not exactly that fast nor are they that precise over the discreet analog component versions.

I wish I had the schematics to this, it would also be pretty cool to see how it exactly works in there. :P
Hopefully once I finish my printer thing I will take the guts out of it and replace it with some other ic's to get much higher frequency and quicker rise/fall times out of this guy. I am thinking of just using an FPGA for the square pulses, and then a very high speed high resolution DAC for the sine and triangle waves. Thought about it once when I was put in a horrifically bored situation, it would be very cool though!

I am checking the book out now, thanks for the link to it! :)
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Re: BK precision 3011B tear down

Postby JanW » Thu Jan 05, 2012 5:11 pm

There is one more standard function gen IC, its the XR2206 by Exar. The ICl8038 and the XR2206 have been around since the late seventies. The waveforms they produce are of acceptable quality whereas the 2206 is better than the ICL8038. You'll find them in many of the cheaper function generators. As with any universal function generator the sine waveform has a too high THD for audio measurements. But leaving that aside they are good enough.

The (now again obsolete) MAX8038 is an beefed up ICL8038 in terms of max frequency range and sine quality.

Building a good function generator with the same specs isn't that easy. If you come across an instrument built around these parts, it does not have to be of inferior quality.

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Re: BK precision 3011B tear down

Postby hak8or » Sat Jan 07, 2012 1:46 am

Thanks for the link to the manuals MickM! :)

And, if I were to try to make my own function generator the chances of it being worse than my current function generator are high, but at least I would learn a huge amount in the process, which would make it worth it for me, and on the 2nd go I would address these problems and hopefully have a more usable piece of equipment. :P Though, if I were to use a function generator, I would aim, with my limited knowledge of DACs, to use a DAC instead of just analog oscillators since it would give me a much more controlled waveform. Imagine capturing a waveform with your scope and then outputting it in a very similar state!

And, the Live AC is not really that much of a risk for me, since I only powered it up when it was fully assembled in the plastic case, but I did not know that it is carried along the PCB like that.
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