[volt-nuts] DAS-46 CSA repair - fixed

[Randy Evans]

Jerry,

I have a DAS-46 that I picked up but have yet to work on it.  I would like
to get a copy of the LTSpice chopper model that you developed.

Thanks,

Randy Evans

randyevans2688 at gmail.com

On Mon, Feb 13, 2017 at 4:57 PM, Jerry Hancock <jerry at hanler.com> wrote:

> Hello, again all:
>
> Interesting thing happened today as the MFE3002 FETs showed up.   You
> might remember I was using the NTE/ECG 220 knock offs.   I plugged them
> into the board tightly and I wasn’t able to zero it.  I then put the ECG
> knockoffs back in and they zeroed.  I thought, what the heck, I paid for
> them, so I put the MFE3002 back in this time reversing them as the board
> uses two.  The risk in touching these is they are very, very static
> sensitive.   It then zeroed with the devices reversed.  The circuit must be
> sensitive to the gate or base voltage somehow.  I don’t know, but it zeroed
> so I soldered them in and the board is working fine now.  It zeros and the
> +/- (normal/reverse) voltages are balanced.
>
> I can now say I am the expert on the DAS-46, DAS-47 and 57 CSA assembly!
>
> Again, if anyone wants to play with the chopper model in LTSpice, please
> drop me a note.  I am adding part numbers where available, etc.  This will
> make it easy for those knuckleheads that follow me.  Now I know why they
> wanted $400 plus 10 weeks for another one!
>
> Jerry
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