General > General Technical Chat

The Rigol DS1052E

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flolic:

--- Quote from: rossmoffett on February 17, 2010, 10:25:15 am ---
I flipped to the underside, flabbergasted, and realized that those vias drop down to a couple more caps on the underside!  In addition to those, there are two other sets near the signal input jack and the input of the variable gain amplifier.

--- End quote ---

Time to take it apart...
AGAIN!!!  ;D ;D ;D

rossmoffett:

--- Quote from: flolic on February 17, 2010, 10:58:45 am ---
--- Quote from: rossmoffett on February 17, 2010, 10:25:15 am ---
I flipped to the underside, flabbergasted, and realized that those vias drop down to a couple more caps on the underside!  In addition to those, there are two other sets near the signal input jack and the input of the variable gain amplifier.

--- End quote ---

Time to take it apart...
AGAIN!!!  ;D ;D ;D

--- End quote ---

I traced the two caps near the variable gain amplifier, they're coming off of the eight lead ADC driver chip.  This is to be expected, they're in the datasheets for the ADC drivers, and there are two filtering the power on the ADC driver in the app note for the ADC.

The other filter is below the relay that doesn't appear on Dave's board, right by the input.  I haven't traced it yet, I wonder if you could do in-circuit measurements of the cap and inductors so we can compare?  The cap is huge for a SMT part, looks like a .1 uF.  If you don't have an L meter, could you get the numbers maybe?  My board is a couple of revision ahead of yours, but I can't tell that there is any difference.

I get 3.37 uF and 15.45 uF on the two little caps near the VGA.
194.2 pF on the cap underneath the relay and negative numbers on the inductor measurements.. guess the cheap-o LC meter can't handle this.  They are both marked "580."

flolic:
Big bottom cap is 210nF.
Two small components next to cap, marked ad 58D are 390k resistors.

Two small caps below VGA must be decoupling capacitors.
Sorry, nothing useful on the bottom side...  :(



Maybe we should look for a components between ADC driver and ADC??

rossmoffett:

--- Quote from: flolic on February 17, 2010, 06:16:15 pm ---
Sorry, nothing useful on the bottom side...  :(

--- End quote ---

Not necessarily true, there are other bottom mount components under the ADC support circuit.

There's also an empty set of pads for an IC and three passive components near the bottom of the FPGA on mine.  Did you take more pictures?

flolic:
Bottom, not so good quality image:

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