Measuring B+ on monitors

[vanwatson]

Where is the Test Point for measuring the B+ on arcade monitors?

The B+ voltage is always set at 120VDC? any reason why at 120VDC

Is this for all arcade monitors you have to set the B+ to 120VDC?

[MonMotha]

Varies with the monitor.  You'll have to find it.  Look for a modest cap or the pass resistor on the output side of the B+ regulator for linear supplies or poke around at the various caps on the output of SMPS designs.

Also, it's not always 120V, but it's usually around there.  Some are 130V, some are 100V, some are closer to 160V.  They're usually in that ballpark though because it's convenient for various reasons.  A lot of TVs are in that range, too.  You'll have to look up what it is supposed to be for a given monitor.

[vanwatson]

What is the B+ voltage setting or biasing in the monitor? is the B+ for the cathode , filament, anode?

Why do they call it B+? what does B+ mean

[vanwatson]

So I would need to get the Datasheets for the arcade monitor? because to measure the B+ voltage is not in arcade manuals for some reason

[lilshawn]

the "B+" as it's known, is the high voltage that is used to drive the circuit including such things as the flyback and the horizontal deflection.

this B+ value is specific to your model of monitor. you will have to gain a specification sheet for your particular model of monitor and see what it is supposed to be set to and what the monitor state must be to gain an accurate reading. Your specific monitor may require you measure B+ with a standard crosshatch displayed at 50% brightness or maybe nothing at all. again, your specification sheet will tell you this.

In --BINGO! Either that, or I was attempting to say "before" but it was too many letters to type-- RIP OP.

CAUTION, the B+ voltage (and related flyback voltage) IS very dangerous. you are working around and with very high voltages that can KILL you dead.

[vanwatson]

the "B+" as it's known, is the high voltage that is used to drive the circuit including such things as the flyback and the horizontal deflection.

So the Vertical Deflection doesn't need the B+ voltage?

Any reason why the horizontal deflection needs the B+ voltage and Not the Vertical Deflection?

The Anode Cap is attached to the flyback , the Anode cap has a very higher voltage then the B+ voltage

So the Flyback amplifies the B+ voltage? is the flyback like a step up transformer?

The Anode Cap is in the KVolts

[ed12]

all circuit's need b+
it is all in the design of the unit at hand..
some smps unit's will provide +120-140 for horz sweep
and a lower voltage for vert-sweep
older linear style unit's
will at time's provide the nessary voltage's from the fly back
again this is all in the design of the chassic in question

the fly back act's as a amp..through the freq and lower voltage provided
will ramp it up to the kv's >24-30kv< on the anode
plus will be divided down for foucs and screen
the freq provided is at horz rate..so the horz output trans is switched on and off
at xx pre sec to drive the flyback transformer

if u truly want some theroy u should ask why do they call it a flyback.?
and get the real outstanding answer most ppl do not know the answer to

ed

[vanwatson]

I think the flyback means something about how the screen retracing flybacks when it's retracing horizontally and retracing vertically

The Focus adjustments and Screen Adjustments divides/voltage divider the Anodes voltage?

Their is a Horizontal oscillator and a Vertical Oscillator that set the frequencys and drive the flyback transformer

The Horizontal oscillator is the Horizontal sweep retracing circuit
The Vertical Oscillator is the Vertical sweep retracing circuit

[ed12]

your colse..but u are missing the exact term...>flyback<
and no vert has 0 to do with it

ed

[lilshawn]

don't worry yourself with the ins and outs of the every little component.

the B+ supplies the main voltage for the board...often other circuits derive their voltages off this main B+ voltage (in particular the mains isolated chassis). if it's not proper, all sorts of weird things can happen.

the "flyback" transformer is so named because the current pulses used to drive the horizontal deflection coil in the yoke is also used to drive the high voltage "flyback" transformer. (because they must be timed identically.)

power that is used to drive the electron beam across the screen then "flyback" to the left hand side again is used to pulse the high voltage "flyback" transformer to produce the several thousand volts needed for the anode connection and the electron beam in the first place.

[ed12]

god i love your reply's shawn.

ed

[Sarver Systems]

My theory as to why its called a flyback: When you touch it, it makes you flyback against the wall.

[Sarver Systems]

Surely someone has a list of common B+ voltages they could throw on here for us.

Also, if possible, to list where to pull the measurements from, indicating "TP1, near blah blah" or "right leg of R22" type of thing.

20EZ, GA07, WG models, etc...

[lilshawn]

ALL B+ voltages are depandant on the chassis used and the tube/yoke combination being used.

for instance my post on the 666 chassis has several voltages depending on the tube/yoke and even between same sub models.

http://forum.arcadecontrols.com/index.php/topic,142602.msg1477280.html#msg1477280

[Sarver Systems]

Ewww, that definitely throws a wrench in the works.

I can see that being true for the WG and others, but the 20EZ and GA07 only have 1 possible combination, right?

Or heck, why don't we just compile a list and make a sticky? Make it a work in progress.

[ed12]

that would be 1 hell of a write up
look at it this way
electrohome g07/08 for example.,
all of it's b+ expect 1 are scaned..meaning they come off of the flyback
where smp's style for the most part,all of the nessary voltage's generaly
come from the smp's.
in some design's they share load
ie b+ regulater then some knock down resister's for a few sub circuit's
>vert<,sync sep's,then the rest of the sub system's use scaned voltage's
so it will for sure make for a big sticky

ed

[Sarver Systems]

I was hoping for a layout like this:

B+ voltages
EHome G07: 120VDC measured from TP1 near flyback
WG 25K7___:
mainboard _____ with neckboard _____: 110VDC measured from R2
mainboard _____ with neckboard _____: 112VDC measured from R2
mainboard _____ with neckboard _____: 100VDC measured from R1
mainboard _____ with neckboard _____: 140VDC measured from R1

Something along those lines.

Of course the blanks would be filled in with the actual board numbers.