Advantest R6551 Multimeter

[radhaz]

I bought this a while back. It's a 5.5 digit DMM, pretty well made. It had an issue where it would not measure ACV or ACI. Turns out there is a separate board for measuring AC, which this unit did not have.
I found another unit for sale cheap and took a chance on it. It has the AC board, but it has a bad transformer. I swapped in the AC board and now have (inaccurate) AC readings.
Here are some pics of the beast:

[Vgkid]

That is a rather interesting meter. I do find it funny to see the 4052 with guard traces.
Gotta love the high impedance daughterboards, and the mix of smd and through hole components.

[radhaz]

Any ideas on a poor man's AC calibrator? I just want to get AC kinda sorta close to reality.

[Vgkid]

Closest to diy, I always wanted to try it.
http://cds.linear.com/docs/en/lt-journal/05_03-12-LTC1968-Pei.pdf

[lowimpedance]

Is changing the transformers over complicated?, or the cheaper unit too beat up?. Just a thought that the one with the dud transformer may actually be okay for cal. with all its 'cards'.

[radhaz]

I may try moving the trans over to the duff unit. I do have soldering gear for that.