For what all these restorations are likely to cost you, you could get a Surround Master, which replaces both the Tate and the QSD-2, with tri-band decoding and a much smaller footprint. Well worth it.
While the Surround Master is very good it is still not as good as a Tate, especially with SQ! I have never thought that tri-banding was necessary nor even desirable, unless your goal is to put bass in one speaker and treble in another. Reduction of artifacts is the often quoted reason for tri-banding but Vari-matrix has no real artifacting and with the Tate decoders it can me minimised, I have never felt it to be a real problem. That being said multi-banding makes some sense if decoding is being done via DSP rather than analogue, it is much easier to implement that way. I'm not attempting to knock the Surround Master which is a great decoder in its own right.
I just bought a Tate II when the eBay seller offered a discount that I couldn't refuse. I already have several Composers!
A few points about it. It appears to be almost a clone of the Tetrasound unit. It would seem that as Jim's companies folded he would quickly start another. Notice the Tetrasound is from "Tetrasound Inc". while the Tate II is from "Fosgate Research Inc".
Differences between the two include no tape monitor on the Tetrasound, just a tape output. Only one remote jack. The surround modes ST1 and ST2 are relabelled as Surround and Cinema on the Tate II. Other than those differences they appear to be much the same. The board layout of both are very similar. It strikes me also how similar the boards are compared to the Composer as well.
The power transformer is the Audionics Space and Image Composers Achilles' heel. The one in the Fosgate looks larger/heavier than the one in the Composer, and (hopefully) less likely to break away from the board. Definitely much better than a wall wart!
The interface circuit distinguishes itself from that of the Composer. In the Tetrasound it is encased in epoxy presumably to protect it's secrets. In the Tate II it is fully visible. The schematic shows it as a block labeled Q8. If I get around to it I might try to draw out the actual circuit, it looks to be very simple, containing only hfe graded 2N3904 transistors, diodes and resistors. My unit has orange dots on the transistors, the one in posted picture shows green, so the important thing is not the actual gain of the transistors just that they all be matched. With greater speed comes the possibility of anomalies so the alternate switch is there to slow it down. In normal use I notice no difference but listening to the rear channels only and adjusting the input balance a difference was noticeable. The Tate II produces a very sharp null of vocal leakage to the rear, extreme separation coupled with fast speed can cause audible artifacts. Rear output was smother sounding under the same conditions using the alternate switch setting, and the null didn't seem as sharp.
Like the previously posted picture my unit looks factory fresh inside. I wouldn't worry too much about re-capping. To Jim's credit he used film capacitors in the signal path. The values are rather small compared to the Composer. Those low values are possible by using high value resistors in audio stages, high impedance causes higher noise but the unit is not excessively noisy. The volume and balance pots were all noisy in operation but a spray of contact cleaner helped to clear that problem up.
Initial impression of the 101A is it works very well on SQ and stereo synthesis. I've been listening to it via the speakers set up around my work bench and computer desk, I was previously listening to my Photlume Vartio-matrix decoder. The Tate in surround mode seems more active than the Vario-matrix although both produce a similar overall surround effect.
I will post more about my particular unit latter.