Sir Leggyownz . . . . .
Wheeeeeeee . . .now we have eliminated multi-millions of possibilities . . . . of what the product involved actually is.
In reality, a "blud slanger"
And is the supplied photo of the power board, in actual agreement with being like your unit ?
Proceeding, in that consideration, I am seing the power section of the system with two other boards handling the control and logic aspects.
On the power board shown, I have marked up the TWO involved neon based optical isolators as the two YELLOW A units.
And considering these to be factory unirs, with the 211-427 ? OI units seems that these are using the larger 1/2 in dia photoresistance detector unit instead of the 1/4 unit used in the
VACTROL VTL3B49 unit that you / I have.
With due diligence that certainly the two are interchangeable, with your unit working satisfactorily in past use with the VACTROL subs of the mods..
My big ones were of FAIRCHILD INSTRUMENTS manufacture.
With further full use of my 18" crystal ball and thorough observations around the board . . . within detail limitations .
WHAT I SEEM TO SEE . . . . .
The far right
RED outlined BLUE E-cap and its
White Red Trace lead over to its far left is its RED B block FWB rectifier companion, thereby seeming to relate to being a 24VDC power supply, with possible further supply voltage subdivision reduction for the 2 other logic level boards.
Back to B FWB and at its forefront is a SOLID STATE relay at X. On the top side direction of B FWB, seems to be one BRUTE of a 3 terminal power relay (220VAC). With it having had a later add on protective MOV block at the RED STAR.
At center panel foreground we have a 3 pole open frame power relay at
Green outlined D.
Suggestive of being 220VAC power function switching with a 24 VDC coil.
So o o o o o, now we have 3 power control relays, and this unit is needing to handle the
HEFTY power demands of a spin motor and a refrigeration cooling pack.
Now the minor aspects . . . the two
YELLOW outlined neon based Optical Isolators at the two A positions.
The left ones close proximity to the D relay suggests of it wanting to be relating to AC voltage sampling of that units condition. Thus the reason of the simplicity of a neon lamp isolator, as it only requires a droping /current limiting resistor for interfacing / sampling of supply AC power voltage..
Looking over to the right A, is the like designated Optical Isolator, now it could be arranged as several connections, with YOU having to peek at the bottom side trace foils for circuitry routing.
Now, it could be that if that F designated carbon resistor is in the 20's - 30's K's of resistance, the White / Red (or violet ?)trace wires just above it go to the monitored AC voltage of interest, and then it series feed thru that resistor to that lamp end of the OI.
That then leaves the left sensor ends 1 lead to go to ground and the other lead to that E capacitors right lead, that otherwise seems to go to nowhere. But would relate to receiving logic input from the sensor.
YOU will know immediately, since you can read the lamp-cell ends markings on your OI. I don't have that advantage.
Now, the opposite wiring consideration would be that double RED marked set of diodes are configured as a discrete FWB set, as is being fed from AC at the
ORANGE and
White / Blue trace wire sets just above them.
The positive DC output passes down to the . . . probably .1 ufd E designated cap. (Since the larger companion just below is a .22ufd.) That DC voltage then feeds the Neon within the left end of the OI, and has the other ends photo sensor feeding out to the F resistor and the White / Red (or violet ?) trace wires, carrying logic output.
Another unknown , until you confirm the situation, seems like a YELLOW Sprague, little Atom, E-cap is the other double RED boxed cap . I suspicion it to be a minor supply storage E-cap that might be having its rectifier set being the 4 discrete diodes constitutig a FWB that are hidden by the wiring cluste down near the caps negative lead. ( Since its Positive leads shell clamp ring crimp shows at the top .)
Passus the info on that YELLOW units capacitance and voltage rating.
ANALYSIS . . . . .
If you have to work naked, without a schematic, you need to make voltage checks at the lamp terminals to see if the lamp is receiving DC or AC and I highly suspect AC . . . . . by virtue of my suspicion of the OI's actual functionalities.
DCuse would only have one electrode glowing and a definite decrease in light output.
It takes up in the low-mid 70 volts to flashover and fire the neon lamp and then it reads in the 50-60 volts while running thereafterwards.
On the sensor end you would now want to take a like reading across its terminals for both DC and AC .
I am suspecting DC, with little or no AC presence. Then you take note of that DC voltage in a system operating state, when the neon lamp is activated.
Then shunt a 47K resistor across the OI lamp leads, right AT its case and take a second reading of the DC voltage, then the effective resistance of the sensor at a nomal state of illumination can be cross computed.
Then you would need the same new OI unit which I have 1 of, for you , to then sub in place of your unit, and establish it as being a benchmark standard , to see if your OI units neon lamp has received enough usage, so as to have started a cumulative and progressive greying of the intenal glass and an accompanied declining light output illumination to the sensor.
Thaaaaaasssit . . . . . . . . . .
PHOTO REFERENCING . . . .
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https://i.ibb.co/k6nKCY9/Beckman-J2-21-Centrifuge.png)
73's de Edd . . . . .
It's not IF or HOW you pick your nose . . . but . . . WHERE you put the booger.