Sir Jerry:


Unitil I consulted your provided photos of your set , I was initially going into the mind set of a transverse traveling /latching bar and its locking feature, such that only one pushbutton is active at one time, and it comes unlatched as another is pressed to be engaged.

Looking at YOUR unit however, it is a MUCH later unit, a Solidified State-amus unit. . .no less. . . and those units used

(after you got them shown with your LAST photo on the second posting) seem to be either Schadow branded switch or else they are using a later “knock off” variant of it.

I created a blow-up of that type of switch, and was tryng to keep any referencing mark-up clutter to a minimum, since its main area of concerned interest is in such fine detail.
Referring to the illustration at the bottom now, I put a “burple” circle around the prime area of interest with the actual latching mechanism being in its very center.

There are three basic aspects to the latching mechanism:
Initially there is the green reference coil spring which presses outward on the square metal stop that clips into a groove in the switch shaft, note that the spring stops and rests against it with a continual outward pressure being exerted upon the switch shaft.


Note part (2) which is the black piece of small spring steel stock (phosphor bronze on some versions)
That is re drawn below the pic, with red reference dots placed upon both pieces, such that you can easier see its mechanical positioning within the switch mechanics.


That black part (2) is held on its proper position by the OTHER end of the prior mentioned spring slipping over the right half of it, covering a portion of it, and thus holding it down.


Now, how does it work ? Well that is actually dependent upon a special grooved pattern that is machined with in that switch shaft at the area in the center of the circle. The item (2) is fixed in position at its right pin end BUT CAN pivot about on its axis, AS the left pin side will be “waggling” from side to side in following that grooved path that I mentioned being within the shaft center.

At one extreme limit of travel, the movable #2 pin end will come to rest and latch into position into an inset within that grooving.


The next time you press the switch shaft, the pin will slip to the side of that holding inset rest and then the outside compression spring makes it return al l l l of the way to the bottom of that grooving and be in its other latched position.

You see the basic mechanics now, so use a BRIGHT hi intensity lamp and inspect the unit, and see if there is not some cruddy built up deposit of aged, yellowed “Lubriplate” residue which is impeding the free lateral and traveling of #2, as well as clogging up the “grooving” path.

I usually use an “acid brush” and denatured alcohol for cleaning out of the crud and the grooves and put Dow Corning Z-5 grease back within the mechanics, as I want a half life of 50 years before another required teardown. The actual switch contact mechanism at the switches rear is actually quite reliable.

Plus, those switch mechanisms have capability of quite a dense switching action within a small area of real estate . . .e.g. the shown unit is a 4PDT unit, I have seen them made in up to 12PDT units.


Plus they were designed with dual contact options, the slotted connections the top for use as wire connection terminals or the pins at the bottom for wiring into a PCB, which yours is using.

However, I ocassionally see a wire or two sometimes routed to those top terminals, so that it can addtionally be included in the connection mix.

Lastly, I have also seen a cheapening of that reliable basic mechanism, with a strip of plastic (blue?) in its replacing of that pivoting spring wire (2)piece.

Switch Mechanics Photo:

After looking thru my WELL stocked Junque Box items , I was only able to find ~36 of those switches, but with all of
them being 4PDT configurations, as well as multiple 2PDT single units and I was certainly hoping for a
ganged unit.


No luck !, but I did remember a Console Professional Audio Mixer Console that used such in its RF
switching section. Now, the amount of switching that unit has been subjected to will make your units
degree of use, pale and paltry by its comparison. HOWEVER this unit still works FINE, with both its
latching and switch contact action integrity included.


That unit was retired, when another unit with solid state switching and other bells and whistles
superseded its use.


It happens to have a cluster of 5 switches. . . . . resplendent with their ganged latching switch action.
I have now examined its manner of operation and now will define it, such that you can now check
out your unit more fully.


My prior suplied info was being solely dependent upon experiences back in the 70’s. . . .quite a memory feat after total dis association approaching ~39 years.



Refer to three main points of reference below. . . . and see initially:


[A]:

CHICKEN LITTLE WAS RIGHT !. . . . indeed. . . . the secret doth lie down deep within the aforementioned square “U” channel in the form of a small latching plate that moves laterally from side to side to accomplish its action.

The draw up shows a view of the plate as one might see certain portions of, when peering down into
the channel, as well as the side view of the folded up tabs that actually perform the action, with the
bottom plate merely shifting , side to side, if being activated.


The colored linking lines lets one fully intra-compare the mechanical drawing to the actual photo of the
switch assembly and its internal layout.


[B]:

A tab on the right side of the cluster is having a small compression spring slipped over it and the
springs right half pressing against the switch housing. The resultant effect is the whole slide assembly
normally pressure shifted to the left.


[C]:

A taking of a switch and examining its internals, reveals the center switch core having the construction as is shown with a key slot at the bottom side--- a ramp molded into the shaft--- and
final key slot at the top side.

The single blue line reference shows the manner in which a switch latching tab would initially rest
down within a slot.

Note that all of the switches are normally continually being pressed outwards by each switches frontal compression
spring.

Should that particular switch now be pressed down, the latching tab would start riding the sloping
ramp such that the whole attached latching plate is shifted to the right, THEN, at the top of the ramp the
tab falls down within the slot and movement stops, that locks the switch in place.
There the switch will remain. . . . .UNLESS. . .another switch is pressed, in which case THAT switches
tab will start riding up ITS ramp and moving ITS tab to the right , until the plate shifts so far that the
LATCHED switch’s tab snaps out if its slot and ITS compression spring snaps the switch to an open and
released position. That same latching action is now being engaged by the second activated switch.

Repeat the same procedure for any additional switch being pressed in.

There. . . . you now have its full modus operandi.



Troubleshooting:



Is the latching bar fully sliding free laterally ?

Is the small compression spring on the right half of the bank present and presenting proper tensioning
to drive the latching bar fully to the left limit ?

Any old lube present . . . .solidified. . .and gumming up the free moment of the mechanism ?


I mention this now, after detailing the latch mechanism, as I feel that prior attention just might have
been mainly directed to the actual CONTACT switching mechanism to the CENTER and REAR of the switch
cluster. The latch action, is actually being accomplished down within that frontal channel.

Observations:


Starting with switch [ 1 ] being latched.
In initial testing of that unit, further press the switch inwards and expect an ~1/8 in additional
movement inwards with only the further “clacking” noise of the latch bar shifting to the right.


Press switch [ 2 ] and then at about 1/8 inch down in its travel, hear the solid snapping sound of
prior switch [ 1 ] coming unlatched, and then, with further downward pressure on switch [ 2 ] hear
another solid snapping sound as ITS latching tab falls into its locking tab.

That will now results in the [ 2 ] switch as now being the designated latched unit. . . . .etc . . .
on down the bank of switches being tested.

MECHANICS OF A SCHADOW FAMILY. . . . . LATCHED SWITCH ASSEMBLY