I snagged a damaged LeCroy ADP305 for less than $20 USD and figured I could mod it into a "dumb" probe that I can hook up to my ancient HP scope (since the "smart" ProBus end of the probe was violently removed from the cable).
For those that don't know, LeCroy's ProBus interface uses I2C and has an EEPROM that stores things like the attenuation and skew of the probe. It's a pretty cool setup that automates a bunch of boiler-plate stuff when connecting up a probe that, unfortunately, I can't use since I don't have a LeCroy scope. Que tears of blood. So anyways, I'm not really bothered that some baffoon ripped off the end of the probe. In fact, it's the only reason I managed to get it for such a good deal. For whatever absurd reason, HV differential probes cost as much as a new kidney... and most don't even have fancy pants EEPROMs doing all the heavy lifting when connecting them to a scope.
Anyways, here's the probe as found.

Here's what one looks like when it still has the ProBus connector on the end. Pretty.

After removing the top label (which was surprisingly easy to do), there are four torx screws holding the top cover on. Pulling that off, we are greeted with this lovely view:

I want to point out that there are an absurd number of adjustments for these probes (12 by my counting). LeCroy states, and I quote, "This probe has no adjustments." LOL. Clearly that's not the case.
Moving on, we have three OPAs (TI THS3001CD), two linear voltage regulators (Ti LM317LM and LM337LM), two diodes, two relays and a whole bunch of passives. The input resistors are 4 megohm SGT26 by EBG. Never heard of them, but they look nice and apparently use ruthenium oxide on an alumina core.


If you were wondering, the PCB has four layers.

Those THS3001 cost (at the time of posting this) $6.661 in 1k quantities direct from TI. Yikes. Just those alone are worth more than I paid for the whole shebang.
Also note the coloring of the wires and the silk screen text. Apparently LeCroy couldn't be bothered to match those up. And if you were paying close attention, you'll notice that not all the wires in the cable are used.
By my counting, there are 9 wires: outer shield, coax (its jacket isolates coax shield from outer shield), red, black, white, grey, blue, green, and yellow.
The PCB has 6 solder points: coax center conductor (J102, 1), coax shield + cable outer shield (J102, 2 and 3), red (J112), black (J110), grey (J111), and blue (J113).
So, green, yellow and white are apparently not used here.

And the business end. Ah, the symmetry.
According to the manual, the ADP305 has switchable bandwidth (100 and 20 MHz), switchable attenuation (1000:1 and 100:1), and supposedly, there is an auto zero adjustment that can be used to remove the DC offset. I assume this last feature is done at the ProBus interface end of things, seeing how there is nothing on the board to do this. But this feature confuses me: If there are only two relays, and I assume U100 is for setting the BW and U101 for the gain of the two non-inverting OPAs, then how do they, and I quote, "disconnect the ADP30x inputs from the circuit under test, perform the auto zero function, and reconnect the inputs" with only two relays?
Well, that's all for today. When I get some more time I'll figure out the wiring and how to acuate the relays. Once that's squared away I'll test the voltage regulators and see if the OPAs are still alive.