Thir Tha fios agaibh . . . . . . .hmmmmmmmmm I seem to have developed a . . . lissssssspth . . . make that
Sir
As best as I am able to " read " that Green on Green board foil layout and with very limited viewing of the push on wire stakes symbolization, this now seems to be my initial inclination of the circuit functions on your friends
" Magnificent Milking Machine " circuit board.
(Ewwwwwww that certainly smarts their udders tits ! . . . . . but milk volume increase is FANTASTIC ! )
INITIAL ANALYSIS . . . . .
Switching between relevant board view sides . . .starting at
BOTTOM LEFT CORNER . . . . .
AC line power is coming in, with its
COLD side going to the
DARK GREEN and it's
HOT side going to the
PALE GREEN which immediately reroutes out thru the
ORANGE STAR and thru the units
MAIN POWER SWITCH which has its other lead connected to the switched HOT area at the
RED STAR up above.
That area has
HOT AC power routed to the hefty triac that does power switching to what I initially suspicioned, as being a
HEFTY solenoid, but by only seeing the
MO..... , has made me think of a geared down, high torque universal motor being used instead .
Then,
IF there is being gate drive to the triac from the MOC3062 driver, which gets its drive from the sole discrete SM transistor at the top of the board.. . . . the units punch action is done.
Since the board is being all sealed away from being touched by a consumer/user, they have opted for an economical solution of the derivation of the units low voltage power for the semis, with a capacitive dropper design of circuit.
The capacitive reactance along with a sometimes used " fine trimming " resistor reduces the resultant AC voltage reaching the Full Wave Bridge, which then DC charges the main C3 filter above. Then finally there is usually a dropping resistor feeding a Zener diode shunted across the circuitry for final upper voltage limit regulation of the supply . . . . sounding like your 12VDC . . . but I see that the main filter was liberally rated on upwards of 50VDC.
AND do I see just the very top 5% of " ZD1 " symbolization, just barely peeping out, at the top, above the main DC filter cap ?
HOUSTON . . . .we have power up ! . . . stand by for sequence of operations . . . .
Now I need some observation, on your part . . . . . to fill in on the
PURPLE mark-up white 2 pin
MOLEX which has one PIN being with full DC power and the other PIN being routed into the two
PINK transistors discrete circuitry.
Also there is being the
Optical INTERRUPTER' s function..
Let's make this my initial stab . . .
Consider that the O.I.. is being for a go no go or validating function.
Like the actual papers presence into the machine, has to physically engage a mechanical "shutter" to the O.I. to validate the unit working, and thereby not " shooting blanks " punch operations.
So that, a completed punch operation might activate the O.I.
If that is the case , the white MOLEX might be related to an ACTIVATE function, such that if you move paper into proper place, and the paper presses into a microswitch that engages a punch operation .
If the last is the situation, I am suspicioning that the shorted microswitch is feeding into the 2 pin MOLEX which ties into the 2 SM transistors discrete circuitry, which are configured as a timed one shot .
It is then using the two
PINK transistors and the
PINK BAR timing capacitor to activate the MOC driver transistor for that DURATION of required rev up operation of the geared motor to do a punch.
HOWEVER . . . .this might be all reversed, with the O.I. doing this job . . .thereby the need of your electro-mechanical observations and defining feedback.
INITIAL TESTING . . . . . . .
Confirm power at the top collector tab of the end of board MOC driver transistor as referenced to power supply power ground at the MAIN filter cap and then enact a punch action to see if a voltage swing occurs with that action.
If so, then proceed to the MOC secondary . . . . on the HOT AC side . . . and and see if drive is being sent to the triac gate.
ADDENDA . . . .
Just now read-ed-ed back, and caught that . . . .That black thing U2 (3rd picture) is a photo switch that senses when the punch carriage returns. . . . . . in the very fine print of the contract.
PLUS . . . the MOC primary DC supply path is . . . .
Power comes left from + of FWB and up and into one pin of the MOC and passes thru the MOC primary and out into a ? value SM resistor and then ends at the collector of the discrete driver transistor.
ALSO . . . . check the voltage at the + of the FWB to see what voltage level it is as referenced to the filter minus.
BECAUSE . . . . they may have used a stacked supply , such that a higher voltage is being there (remember the 50V rating of the cap ) instead of ANOTHER lower voltage that the are deriving by holding the 12 VDC above ground, for deriving its second supply level (12VDC).
So . . . . if you find 12VDC across the ZD1 and a HIGHER +DC voltage at the FWB + connection, that is exactly what they are doing..
Thaaaaaaaaaaaasssssssssssssit . . . .'fer now
SCALED COMPARATIVE BOARD LAYOUT . . . . . . .
73's de Edd
......................
ALWAYS REMEMBER ! . . . . . . this timely tip . . . .
It is far, far better to break wind, and then head INTO the wind, than to break wind and head downwind.