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EHT or Extra High Tension is the power supplied to the final anode of the cathode ray tube.
The EHT is traditionally generated by the line transformer from the flyback pulse of the line oscillator/amplifier.
The generated high frequency high voltage current was from the outset rectified by a thermionic diode (eg. EY51, EY86) but by the late 1960s/early 1970s technology brought high voltage diodes and semiconductors rapidly replaced the old technology and the output from the line transformer then typically fed the anode via a semiconductor voltage doubler.
The rectified EHT was originally smoothed by a high voltage oil-filled capacitor but that was soon deleted in favour of spraying the outside of the CRT with a metallic paint and grounding it. This became the high voltage smoothing capacitor with the glass of the CRT being the dielectric and the final anode the positive pole...
Voltage measured on DC scale, black cable multitester / avometer put on a negative path or can be slipped on the silver wire in the tube that is not disposable wrapping.
Next, measure the voltages are available:
For 180v voltage can be measured on the positive pin elco (10uf/250v) in PCB RGB tube.stick pin red wire multitester
Voltage 110v for TVs 14 "-21" and 130v for 25 "-29" in the B + FlyBack Transformer (FBT), find the path there is elco 100uf/160volt. measure on a positive foot elco.
For 12volt voltage, please measure at the foot of the right edge of IC 7812.
For voltage 5V, please measure the right foot of IC 7805.
For voltage 33v, please search at the foot of VT in tuner.
To measure 90v-300v, scale use DCV 250.
To measure the 12v-40v, use a scale of 50 DCV
To measure the voltage of 1V-9v, 10 DCV-scale use.
How to measure the voltage on the yoke and in plyback is;
From the yoke horizontal = Fcc 110v DC, 1000 V. AC voltage can be removed with a red plug in output and in use as dB meter.
From the yoke pertikal 24 DC current model, except for disposable coupling C = 1 / 2 Fcc. While it could be IC 120V AC (with dB meter)
At Fcc FBT kolector; 110v DC, AC voltage = 1000 V..
At Fcc FBT filement / heater = 5V-5, 5V AC.
In the FBT 20-32k anode voltage V measured with 40kv HV probe is added to the multitester 1000 V. DC.
Voltage others depending on model and type of TV. 180v out there (for RGB) directly from the regulators, transformers, Video Amp taken from FBT.
There are 24V and 46v vertical FBT, also 12-18V depending on brand and type.
Voltage 600 V DC and focus around the screen 400v DC.
Thus tip n trick from me (AGUS YUSTIARA ), hopefully useful.
for more info , at http://trend2download.blogspot.com
OK, what is the input voltage? I will give you a ruff diagram here. (volt in)
Vcc--sw's-on/off/IR-control board (microprocessor)---ccfl (cold cathode
fluorescent lamp) inverter (changes DC voltage tow switching DC (such as
on/off/on/off/on/off but at a much faster pace (20Khz)---toroidal coil (this
coil will step the switch DC voltage up to about 1000 to 1500 switch DC volt,
then this coil will change the orientation of the voltage to current
relationship by shifting the current by 90 degree's where it lag the
voltage---this process has some changes on circuit and how it works)----OK, from
the ccfl inverter------voltage multiplier (all this some HV capacitors and HV
diodes hook up an configuration where each stage will double the voltage that go
into... EXAMPLE: 4 stage voltage multiplier for each stage now it double the
voltage 1500V input to 1st stage--output to 2nd stage 3000V output to 3rd stage
6000V out put to 4th stage 12000V switching DC, they will also refer to this
voltage AC voltage because AC switch to from - negative voltage to + positive
voltage.
Like in you case, the two volts from the controller to ccfl. Out put volt
from ccfl with be around 2.4 to 2.6 due capacitance discharge, Now this voltage
will be divided in the ccfl by two input windings (I am not going to explain
this). Now the two input winding will induce voltage to the secondary winding
(step up). The output from secondary of toroidal coil will be multi switching to
the voltage multiplier. Probably in the neighborhood of 1500 switching volt. How
many stages the voltage multiplier has I don't know. The ignitier voltage to the cathode from the
multiplier would be around 12000 voltage to get image intensifier tube to fire.
stewbison
sohan472004, An "INVERTER CIRCUIT" lights-up the thin "cold-cathode-fluorescent-lamps" inside lcd monitors by taking a low-voltage dc voltage (10 to 20 volts dc) and converting it to a high frequency 30khz to 100khz ac voltage (500 to 1100 vac) The same principle of operation is used to light-up those new style, curlieQ,energy-efficient,screw-in CFL light bulbs. Only their tiny "electronic-ballast" circuit is called a "CONVERTER" circuit.
AC to AC Hope this helps. 12fixlouie
What is the type (input, output, power) of the rectifier.
If controllable - may be the control PCB or thyristor. If not controllable - 10 V DC instead of 230 V DC is hardly believable. In this case the rectifier may be OK, but the input - low. If you have a voltmeter, check the input AC and the output DC if the output has about 200 V AC you may have shortened diode.
The magnetron is a tube with a heater/cathode element in the middle of a series of scallop-like grooves that surround the cathode, but spaced away from the cathode. A small, insulated wire protrudes into one of the scallops and extracts the microwave energy that passes down the wave-guide, past a fan-like device called a stirrer that scatters the energy just before entering the cooking cavity.The magnetron requires a low voltage/high current AC heater supply plus a 3000 to 5000 volt DC supply that is hooked to the cathode of the magnetron. The transformer supplies both voltages as AC waveforms. The diode makes the HV AC supply into HV DC by passing current in one direction only and the capacitor stores/smooths that HV DC into relatively stable DC for connection to the cathode of the magnetron. The other side of the DC supply is tied to case ground as is the outer case of the magnetron. This arrangement is typical of all microwave ovens (and radars).
You need to transform the voltage to a level that you require, then 'rectify' your voltage to DC, with a bridge rectifier. There are many different types of rectifiers for different uses. Look on the web for electronics, bridge rectifiers.
Questions:
1. Does the AC cord look ok? Not damaged?
2. Have you tried another AC outlet?
3. Does the AC cord unplug from the radio?
When you operate the radio from the AC power cord, the radio uses an internal power supply consisting of a step-down transformer, rectifier, and filter that converts the AC to DC to operate the radio.
When you run the radio off of batteries, it powers the radio directly. In some radios, when you plug the AC cord into the radio, it activates a switch that disconnects the battery voltage to the radio so that the batteries wont be damaged from the voltage created by the internal supply.
The radio can be powered by either the batteries or the internal supply. You don't want either supply affecting the other, so that is why a switch is sometimes used.
Since the radio works fine off of batteries, that would indicate that there is a problem with the internal power supply. This could be a blown fuse, bad transformer or bad rectifier diode.
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