Showing posts with label Arc length. Show all posts
Showing posts with label Arc length. Show all posts

How to Repair Sony Wega TV Trinitron2020

March 20, 2020

How to Repair Sony Wega TV 


Friends I Shahbaz welcome you at Electric Point
in this video i will show you to repair Sony Wega CRT YV
this TV is faulty and only blinking red indicator light four times
so in this video you will learn why this red light in blinking 4 times
so lets start the video
firstly transformer, with rectifier diode, will convert AC voltage 46V DC
on stand-by condition diode will have 46 voltage
but on 'ON' condition diode will 132 V
But TV is still receiving 46V when it is on 'ON' condition
this blinking red light indicated that the TV circuit is open from somewhere
thats the reason TV voltage is dropping from 132V to 46V
lets check from where the circuit is open
transistor and EST are not receiving the voltage from rectifier diode
so we will check our circuit before EST
there is a crack in circuit plate
it provide hinderance of voltage to EST
lets attach a shunt through this crack

How centrifugal pumps work2020

March 20, 2020

hey there guys Paul here from the

engineering mindset calm in this video
we're going to be looking at centrifugal
pumps to learn the basics of how they
work the different types and where we
use them you can get more information on
centrifugal pumps shop for parts and
accessories or talk to experts on top
centrifugal pumps come in many shapes
colors and sizes but they typically look
the pumps consist of two main parts the
pump and the motor the motor is an
electrical induction motor which allows
us to convert electrical energy into
mechanical energy this mechanical energy
is used to drive the pump and move the
water the pump holds water in through
the internet and pushes it out through
the outlet as we take the unit apart we
can see that we have a fan and a
protective casing mounted at the back of
the electrical motor then inside the
motor we have the stator the stator
holds the copper coils and we're going
to look in detail at that a little later
in this video
concentric to this we have the rotor and
shaft the rotor rotates and as it
rotates so does the shaft the shaft runs
the entire length from the motor and
into the pump this thing connects into
the pumps impeller some models of
centrifugal pumps like this one will
have a separate shaft for the pump and
the motor separated shafts are joined
using a connection known as a coupling
couple pumps will usually have a bearing
house which as the name suggests houses
the bearings the shaft continues into
the pump casing
enters the casing it passes through a
gland packing and the stuffing box which
combined to form a seal the shaft then
connects onto the impeller the impeller
imparts centrifugal force onto the fluid
which enables us to move liquids such as
water through a pipe the impeller is
enclosed within the pump casing the
casing contains and directs the fire
water as the impeller pulls it in and
pushes it out therefore we have a
suction in that and a discharged outlet
at the back of the electrical motor we
see that the fan is connected to the
shaft when the motor rotates the shaft
the fan will therefore also rotate
the fan is used to cool down the
electrical motor and it will blow
ambient air over the casing to dissipate
the unwanted heat if the motor becomes
too hot the insulation on the coils
inside the motor will melt causing the
motor to short-circuit and destroy
the fins on the outside perimeter of the
casing increased the surface area of the
casing which allows us to remove more
unwanted heat the electrical motor comes
in either three-phase or single phase
configuration depending on the
application we're going to look at
three-phase as this is the most common
inside the three-phase induction motor
we have three separated coils which are
wound around the stator each coil set is
connected to a different phase to
produce a rotating magnetic field when
we pass AC or alternating current
through each coil the coil will produce
an electromagnetic field which changes
in intensity as well as polarity as the
electrons passing through it change
direction between forwards and backwards
but if we connect each coil to a
different phase then the electrons will
change direction between forwards and
backwards at a different time compared
to the other phases this means that the
magnetic field of each coil will change
in intensity as well as polarity at a
different time compared to the other
phases to distribute this magnetic field
we rotate the coils 120 degrees from the
previous phase and insert them into the
stator of the motor casing this will
create the effect of a rotating magnetic
field at the center of the stator we
place the rotor and shaft the rotor will
be affected by the rotating magnetic
field and will force it to also rotate
the rotor is connected to the shaft and
the shaft runs from the fan through the
rotor all the way up to the impeller
this way when the rotor rotates so will
the impeller so now by creating the
rotating magnetic field within the motor
we spin the rotor which spins the shaft
and this spins the impeller looking at
the pump casing we find a channel for
water to flow along which is called the
volute this volute spirals around the
perimeter of the casing up to the pump
outlet this channel increases in
diameter as it makes its way to the
outlet the shaft passes through the
seals and into the pump casing or it
connects to the impeller there are many
types of impeller but most will have
these backward curved vanes which will
either be open semi open or closed with
some shrouds these backward curved vanes
do not push the water
the curves rotate with the outer edge
moving in the direction of the expanding
volute these vanes will provide the
fluid with a smooth path for the water
to flow we'll see that a little later in
this video the impeller is submerged in
when the impeller rotates the water
within the impeller also rotates as the
water rotates the liquid is radially
pushed out in all directions to the edge
of the impeller and into the balloon as
the water moves outwards off the
impeller it creates a region of low
pressure which pulls more water in
through the suction Inlet the water
enters into the eye of the impeller and
is trapped there between the blades as
the impeller rotates it imparts kinetic
energy or velocity onto the water
by the time the water reaches the edge
of the impeller it has reached a very
high velocity this high-speed water
flows off the impeller and into the blue
where it hits the wall of the pump
this impact converts the velocity into
potential energy or pressure more water
follows behind this and so our flow
develops the volute channel has an
expanding diameter as it spirals around
the circumference of the pump casing
as it expands the velocity of the water
will decrease resulting in pressure
increasing this expanding channel
therefore allows more water to keep
joining and converting into pressure so
the discharge outlet is therefore a
higher pressure than the suction Inlet
the high pressure at the discharge
allows us to force the fluid through
pipes and into a storage tank or around
a pipe system the thickness of the
impeller and the rotational speed
affects the volume flow rate from the
pump but the diameter of the impeller
and the rotational speed will increase
the pressure it can produce centrifugal
pumps are represented in engineering
drawings with symbols like these they
can vary slightly from this so do check
the drawings information section in psh
a term you're going to hear is the NP s
H which is the acronym for net positive
suction pressure will briefly cover what
this means there are two letters at the
end of the acronym the NP s HR and the
NP SH a the R is the required MPs H each
pump is tested for this value and this
can be obtained from the pump
manufacturer by the pump operating chart
don't worry about this confusing looking
chart at this point we're going to break
it down and cover that in detail in a
dedicated video links to that in the
video description down below the r-value
is basically a warning or danger point
as the water enters the pump and flows
into the impellers eye it experiences a
lot of energy due to the friction this
will give us a pressure drop at certain
conditions the water flowing through
this section can reach boiling point
when this occurs we refer to this as
cavitation we're going to see more on
that in just a moment the other letter
was the a and this is the MPs H
available this depends on the insulation
of the pump needs to be calculated it
considers things such as insulation type
and elevation liquid temperature liquid
boiling point etc the available pressure
should always be higher than the
required value for example if we have an
insulation and we calculate the MPs H a
is 11 but the pump requires an MPs HR of
4 then the
pomp should be okay however if we
installed a pump that required an MPs HR
of 13 then the available MPs H is
insufficient and cavitation will occur
so what is cavitation as we know water
can turn from a liquid state into steam
or gas state we know that water boils at
around 100 degrees Celsius and that's
because is at sea level which has an
atmospheric pressure of 101.325 kpa but
if we went to the top of Mount Everest
then water boils here at just 71 degrees
Celsius and that's because the
atmospheric pressure has reduced to 34
kPa as the atmospheric pressure reduces
it becomes easier for the water to boil
so with the suction inlet of the pump we
know that there is going to be a
pressure drop and if this pressure is
less than the vapor pressure of the
liquid being pumped then the water can
reach boiling point when this happens
cavitation occurs during cavitation air
particles within the water will expand
as they reach boiling point these will
then collapse in on themselves very
rapidly as they collapse they will
damage the impeller as well as the pump
casing this removes small parts of metal
from the surface and if this keeps
occurring then it will eventually
destroy the pump
therefore we must insure the available
pressure is higher than the required
pressure of the pump
we use centrifugal pumps everywhere we
use them to move liquids from one tank
to another or around the system for
example we might use a small in-line
centrifugal pump in our domestic heating
circuit to move heated water around the
property we might use a large
centrifugal pump to move the condenser
water from a chillers condenser and up
to the cooling tower on the roof as part
of the centralized cooling system we're
going to look at the type of pumps and
their application in our next video in
this series okay that's it for this
video but to continual learning then
check out one of the videos on screen
now and I'll catch you there for the
next lesson

Troubleshooting and Repairing Electric Kettle2020

March 20, 2020

Troubleshooting and Repairing 

Electric Kettle2020

but you the customer is saying when you
switch on the power the light is glowing
but it is taking very long for the water
to heat up it's not heating up at all I
think the issue is with a heating
element because the supply points are
okay why don't you have a look at it
friends this was one cause but there can
be many problems that an electric kettle
can encounter let me show you how to
inspect all the parts of an electric
kettle welcome to this session on
troubleshooting and repairing of an
electric kettle in this session you will
be able to troubleshoot an electric
kettle repair an electric kettle
valium friends Raju is confused but he
had just fixed one last week friends
there are many types of cattle available
in the market but they all function in
the similar pattern
let us understand the working of a
kettle through this circuit diagram when
the power switch is on the supply from
the switch flows to the heating element
the supply to the heating element is cut
off when the prescribed temperature
rating is reached
let us keep our tools and equipment
ready for troubleshooting and fixing
nyan desktop
some wiring cables
why a stripper

test lamp
friends never forget your personal
protective equipment like your what are
these no gloves and your rubber shoes
even while troubleshooting and repairing
of equipments remember gloves and your
shoes so Raju you now know what parts
can go wrong in an electric kettle
the input supply points that includes
the power on switch plug and the cord
then next is the auto cutoff switch and
then the heating element come join me
and raise you on the troubleshooting
friends let us first inspect the supply
points there are two supply points one
on the kettle and the other one on the
outlet plug socket
let us first check the supply points on
the kettle
always remember to pour water in the
kettle before you switch on the kettle
the supply is on
and the power on switch is functioning
so let us now see the procedure
the next input supply point the plug and
the cord
step one check the plug guard for any
insulation damages
step two check for any visual damages in
the cord and plug
replace the cord if it is broken or has
open insulation in this case the cord is
step 3 check for loose connections or
open insulation in the guard unit
locate the screws for opening the cord
unit below the kettle baseplate using a
screwdriver open the screws and remove
the cord unit cover
step four disconnect god terminals from
the kettle
step 5 check the code using a test lamp
connected in series
to check the code you need to check both
the phase and neutral wire one by one
first check the phase terminals of the
place the cut wire connected in series
on the phase terminal of the god and
phase terminal of the test lamp on the
phase terminal of the plug the test lamp
glows so the phase terminals are okay
next check the neutral terminals of the
place the cut wire connected in series
on the neutral terminal of the cord
and place the phase terminal of the test
lamp on the neutral terminal of the plug
the test lamp glows so the neutral
terminals are okay
similarly check the earthing of the cord
place the cut wire connected in series
on the earthing of the god
place the phrase terminal of the test
lamp on the earthing of the plug and
the test lamp glows so the earnings are
also okay and this confirms that the
plug cord is okay
case in any of the checks if the test
lamp does not glow then the cord plug is
faulty replace the cord plug
now let us check the kettle again with
step 6 pour water in the kettle a little
above minimum level
step 7 plug the cattle to the outlet
step 8 switch on the socket power
step 9 switch on the kettle
in this case the kettle power switch
closed then there is no fault in the
supply point at the kettle end so there
is a problem with the heating element
for the water not heating
step then
of the cattle power
step 11 switch off the outlet power
step 12 unplug the kettle
here is a chart which sums up the
inspection of supply points
let us see how to inspect the auto
cutoff switch and the heating element
for faults for this we need to open the
kettle and remember to empty the water
out before you open it
step one unplug the cord from the outlet
on the switchboard
step two remove the kettle from the base
step 3 locate the screws fastening the
base of the kettle
step four using a screwdriver open the
screws and carefully remove the base
step 5 locate the auto cutoff switch
check it visually for any damages in
case the cutoff switch is damaged
replace the switch in this case the auto
cutoff switch has no faults so let us
check the heating element step 6
now locate the heating element in the
kettle and its connections in the kettle
step 7 using a multimeter check for
set the multimeter dial to resistance
place the REDD+ probe of the multimeter
on the phase terminal of the heating
element place the black negative probe
of the multimeter on the neutral
terminal of the heating element
check the reading on the multimeter in
this case the multimeter shows zero ohms
this means that the heating element is
step it now let us check the heating
element using a test lamp connected in
place the phase terminal of the test
lamp on the phase terminal of the
heating element and the cut wire
connected in series on the neutral
terminal of the heating element
the test lamp does not glow so this
confirms that the heating element is
faulty yeah the heating element is the
culprit but in this type of kettle we
cannot replace the heating element we
will have to replace the kettle friends
let us see how to assemble the kettle
back you don't want to give it back to
the customer like this right and you
need to know how to fix it back step 9
assemble the kettle
and remember if you have replaced or
repaired the kettle check for it
functioning before delivery
now take a look at this chart to some of
seizure of inspection of a kettle
friends there are many models of cattle
in the market ones with the thermostat
and the other ones with the cutoff
switch like in our case here the cutoff
switch plays the role of the thermostat
if the thermostat is attached you will
need to inspect it let us summarize all
the problems an electric kettle can
encounter and there are causes in the
troubleshoot guide

How to fix the electric motor start key 2020

March 20, 2020

How to fix the electric motor start key 2020

okay I have a little problem with this
motor here so let's see what its gonna
do okay so what's our problem with it
well the things probably got a bad start
switch that would be my guess
normally I just throw this motor away in
the field I don't have time to fool
these things so I can't get parts for
them or anything but this is something
I'm doing at home so I thought I'd take
this thing apart we'll see if we can
figure out what has happened to it
if we can get it going again here's the
motor apart this is the end bell with
the start switch here I've disconnected
these wires and of course I photographed
them so that I can get them back on the
right terminals so let's see if we can
figure out what's happening looking
inside this motor this is what I found
now this looks like cement dust to me
okay that's probably what got inside the
centrifugal switch contacts so I'm going
to blow this out of here well one of the
first things I'm gonna do is I want to
protect this bearing so I'm gonna put
some tape around that bearing so that I
don't get of any of it inside the
bearing itself looking at it now that's
made a lot of difference now here's a
look at these contacts you can see them
right there now normally they're like
that when the motors off and they're
closed and then when the motor speeds up
it opens and drops out to start winding
now what I wanted to damage
straight and I'm gonna show you the
meter is these things are making contact
so when I close them I don't get a zero
reading on my own meter now here I'm
going to check those contacts with a
meter the leads are good the meters good
but when I close these contacts nothing
happens so they're not making contact in
there and my bet is that cement dust has
blocked the contacts now I've tried
running paper through the contacts and
see if I could clean it up there a
little bit of cardboard that those are
standard things I would do I don't like
to use abrasives on this because these
are just plated and if you file them
you'll file right through that plating
but I wasn't getting anywhere so here's
what I did
so I have a disc of 1200 sandpaper very
very fine and I thought well maybe if I
use this and do a light scratching on it
it won't go through the plating so let's

see what happens
I'm not putting very much pressure on
this at all okay I'm gonna leave it at
and let's see what happens
okay it's working every time now if I am
very lucky I fixed it and we'll get this
thing back together after a few swear
words and and so on
I got all the wires back on of course
I'm using my camera to make sure I got
it right all I got to do now is get this
back on and tighten it up okay a few
more swear words and I think we're gonna
be able to get the screws to pull it in
the rest of the way and we'll fire it up
and see what happens
here we are put it all back together and
let's see if it works
it's like downtown
so do I get another 20 years out of this
well I don't know the last one went
almost 40 so yeah it is working I don't
know if that switch is going to stay in
operation because I did have to use
abrasive to clean it but it is working
every time that's it on this one

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