Sir Xgamer . . . . .
Ahhhhhhhhhhhh-sooo. . I wasn't expecting that units, additional, most honnable "black box" baggage.
I was basically only perceiving of just 3 or 2 wires going from a wall outlet, plus a power switch and then wiring going into a bare naked motor.
In the situation now, I can see the breakdown of the use of the discrete components in the top half quadrant if the PCB as being two small signal transistors , rectifier diodes for a power supply, with its associated filter caps and a 1watt zener regulator diode.
That circuitry all results into a created DC drive signal to be sent over into the base of the heat sinked Q1 POWER transistor, down just below.
This all leads up to our need of making an analysis, and thereby ascertaining if the then freewheeling motor, after turn off, is being dependent upon a short being initiated across the motor winding for braking OR if a timed out DC voltage is applied to the motor for braking.
OK now . . . . in filling you in on that loose "ceramic capacitor " that you are dealing with .
Au contraire . . . . .I do believe that device is ACTUALLY being an Negative
AC inline surge thermistor . . . . and with it being of the resistive family . . . .it is thereby acquiring the R
-8 board designation.
Plus, some are capable of getting hot enough to melt solder***, whereas, that is NOT being the situation of a common ceramic disc capacitor.
*** Plus, its falling loose to the bottom of the case, if its mounting plane involved some gravitational downward pull.
If you are not familiar in seeing these devices different case profiles, you might be finding / seeing one as a bare naked unit as in A or with a thermoplastic covering as at B and a final and optimal ceramic fired coating at C.
# Kodachrome . . . . . . . thermistors
Now, that units RED device at center PCB should be an varistor, for chopping voltage transient peaks. You might also mistake that unit as being a covered disc ceramic capacitor.
Now with your mentioning the unit using a set of pushbuttons for power on and off function lets make our first test as seeing if our heat sink mounted " Q1 " device is being an on-off power switching transistor . . . I'm not expecting so, with its !! 80volt !! rating.
Its emitter is the lead closest to the RED Varistor and the center lead is the collector and the extreme far lead is being the base.
So get DVM in hand and switch to its DC voltage mode and negative probe to the emitter and the positive probe to the base . You want to then power up the motor and see if there is being in the order of ~<1vdc on the metered emitter to base connection.
If you don't have an autoranging meter . . .to be on the safe side . . . .start at 500VDC and switch on down ranges, until eventually being readable.
Then press the off button and see if that voltage doesn't dissappear .
If this holds true, that is your switching for the motor and our braking action must be accomplished on the bottom half of that board and is dependent upon rotor derived voltage . ( Still skeptical )
Now confirm this . . . . . notice that you have a BROWN wire that loops from a bottom boards push on terminal to a top of the board push on terminal .
Then there are the paired center BLUE push on wires that join at the PCB foil, as being one connection.
Finally the BLACK push on wire.
Lets now have you take the possible AC voltage readings between those possible combinations, as quickly as you can , just after a power off.
Brown to Black
Brown to Blue . . . . . thinking that this will be the high reading one
Blue to Black
Find the combination with the highest initially developed decaying AC voltage and then that will be the pair that we will be wanting to short together with a double clip ended test lead just as soon as is possible, after power turn off.
Confirming that short is then intiating a braking action.
More info is needed . . . .particularly the resistance reading across your R8 ersatz "ceramic disc capacitor " . . . I'm expecting it having to be taken out of circuit to get a true reading . Also be VEWY-VEWY carefull in not bending the leads, if being a naked / side lead soldering visible unit.
I'm expecting a sub 100 ohm reading.
I needed that part number of the 2N6388 POWER transistor . . . . as it seems like I could only make it out as a possible 2N**99/88 on the top line.
It turns out to be an NPN POWER and its 80 V
-10 A -40W- β 1000, specs would not equate with being a power switcher.
BUT, possibly, merely eing used for switching in the braking function with a period / threshold being set by the BLUE trim pot + its associative timing capacitor.
Confirm the marked number on the RED varistor for us.
Your submitted and "errant" O41 part should properly be read as a D41 . . . as in diode. On this board, if you look at the peep thru foil traces two smaller diodes were being in parallell originally. Now they are using but a single LARGER diode.
Reflected light on the boards left and central areas, inhibits me from further "reading " of the board foil paths contrasting traces.
That diode may end up being used to rectify the generated voltage of the unit after power off , by the still spinning rotor, and used for DC braking.
But. . . IF . . . there is an open circuit by an open R8, that circuit action is never being accomplished.
73's de Edd . . . . .
Cannibal Axiom #1:
Eat the rich. The poor are tough and stringy.