Sir Walt . . .



Seems like I have all of the earlier RCA vacuum tube equivalents of that TVM (Transistor Volt Meter) , but not having that actual unit.
(Instead, having a pair of the equivalent TRIPLETT's in their large rectangular black bakelite cases with their
large scaled meters.

I am familiar with several transistor arrays within an IC to be used on constructing with outboard circuitry.
But I am eliminating the ones in DIP packaging, as well as those that have many more transistors than are needed.
My personal choice would be an older unit that was originally introduced by RCA as being the
CA 3018 which has 4 internal transistors.
Even in that selection, my choice would be in their L casing profile which is akin in apperance to a short, squatty TO-5 metal casing as is so commonly seen.

Its distributon was later taken over by GE and was also being second sourced by Harris.
The last ones I used came from BG Micro, and I see that they still have stock as their:

http://www.bgmicro.com/index.asp?PageAction=VIEWPROD&ProdID=12721

It has twelve 1 1/2 inch leads , which ALMOST permits a connection to ALL of the individual CBE's of each transistor, or some versions have shorter clipped leads for socket insertion .
The transistor lead connections mandated the need of one additonal lead, so they figured that one pair might get used as a Darlington configuration
so you see an emitter of one transistor tieing internally to the base of another transistor but a common lead permits access to the pair.

Now, in looking at your units circuitry, we can see how that does occur within the circuitry in two places, therefore the unit is usable.

Consider taking that metal housing and placing on the component side of the PCB so as to permit its positioning to a central core of the original layout of the WB500 series 4 NPN transistors.
If it seems that one or two leads are insufficient in length use butt splicing with spaghetti covering, for the extending of any wire leads necessary.

Get one of these units, try it, and see it it doesn't fulfill your needs on the repair of one instrument.

Here is the data sheet for the CA3018:

http://www.datasheetarchive.com/pdf-datasheets/Datasheets-12/DSA-236969.pdf

My familiarity of that unit would be the production of photo resist pattern layout on a 3 inch wafer (At that time frame--but up to 12 inch wafers are in use nowadays, so I would be scared to venture the custom individual little dies with 64 transistors on it, as being a yield from a GIANT wafer.)

Then put the whole 3 in wafer thru, etching, doping and individual forming of the semiconductor layers and the overlaying metal deposition of contact areas and then run the unit thru the initial testing of transistor units on that wafer and the isolation of mechanically bad or electrically failing units with a dye marker dot. The whole unit then gets scribed so that the individual sectors of 64 transistors can be broken apart to yield thousands of mini ~.1 inch "dies".

Take one tiny "die," which will be your 3018 and its 64 transistors on it, and move it to subassembly stage, where it is mounted and centered on a ceramic bisque slab on the base of the IC casing with the 12 leads end stubs sticking up around the periphery.

There is micro robotic positioning and application of probes to the individual CBE lands of each transistor for plotting each unit’s specs and performance and storage to computer memory. After computer comparison of all units, the best matched units are spit out location wise and then a REAL person finds those individual transistors positions and using robotic probe control with additional use of high power stereo microscope magnification, moves in to spot weld micro-micro gold wire from C, B or E metal deposition contact lands to the proper adjunct end stub contacts of the terminal wires.

The end result is you’re having the best of the best of the matching characteristics of those transistors as being your choice selected 6 units.

Look at the specs of 5% matching of those units,that being the MAX permissible specrum spread, with reality kicking in at about 2%. Try doing that with a bag of, even 1000, separate and individual transistors !

BUT the main thing that you are wanting . . . . is the fact that all the units were manufactured with a single chemical passification, gaseous activation and additionally, are now mounted on the same shared substrate, for its consideration of shared thermal characteristics.

That, not to be attained via separate, outboard, use of individual transistors.

I see that I also had encountered the need to supply the schematic on the RCA 500 series of units in some time past. Refer to it also, if so needed, on this prior posting of:

http://www.nostalgiaair.org/forums/Messages/142/M0062142.htm