Joined: Dec 07, 2011
|Posted: Fri Jul 12, 2013 10:13 am Post subject:
Frac Rack Mini Oscilloscope
Subject description: Adapting a small digital Oscope for modular use.
|Here is a little 'How to' on taking one of those Mini Oscilloscopes ,floating around on Ebay and mounting it to a frac rack panel.
These are compact 1Mz ,two channel digital scopes ,that can be had for about $40.I bought two of these about five years back..there seem to be kits out there now ,aswell. The advantage of a kit would be less steps ,as dis-assembly would not be necessary .
First , remove the screen ,from the PCB by carefully cutting the header pins.Cut closer to the screen side,but leave enough,so you can grip the pins with pliers ;later.
After the screen is removed ,desolder & remove the header pins on the screen. Leave them on the PCB. Then desolder & removed the two potentiometers on the PCB.Be sure to clean out the PCB holes.Be vary careful not to damage delicate solder pads.
You will be doing a lot of this...
Then use a thin ribbon cable to reconnect the screen back to its header..
Here is the back of the screen....
Use great care in making these connections.Check with your multimeter ,for continuity ,and shorts between pins,as you go..
Time to lay out your panel..the trick is to make sure your components clear each other behind the panel...
Some art work is generated on the computer & printed out.
I like to print out two versions ; the nice glossy full graphic version ,that will be laminated & glued to the panel..& a simpler version ;without graphics,on a thin paper. That one I tape to the blank panel to mark for holes,so everything lines up.
Then get to work on the panel..a port is cut for the screen.the holes are drilled for the buttons & pots...this can,of course be done with hand tools.
After all the holes are drilled ,deburred , & all the parts are test fitted, the laminated art work can be glued on.
Use a thin metal plate to support the PCB..holes are made in the plate that line up with the first row of switches.these are then used to hold the plate in place..
Wiring up the switches is simply a matter of wiring these SPST normally open switches ,on the panel.in parallel to the switches on the PCB.I used little ribbons ,for these ,as well.Just tin the ends of your leads, then heat them into the contacts at the base of each switch .It wont matter if they are reversed ;they work either way.The pots are 10k linear ,and they also use a ribbon to connect to the pads where the old pots where.
Then use a shielded wire to hook up your input jacks to the PCB.I used two jacks ,wired in parallel for each channel,so I could listen as I watched the input.
After that ,glue in your screen with sum silicone adhesive.I covered some of the pins on the screen with tape,so that no pins would short against the back of the panel.Also glue down your PCB to the bracket.making sure that the PCB is insulated from the bracket.Mine came with rubber feet ,so that was not an issue.
After I confirmed it was all working : I added glue to add strength to some of the connections...
Here is a picture with a square wave input, on channel one...
Here is one with a sine wave input....
And a triangle wave input...
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