FACING SOME PROBLEM IN CRT SCREEN.
This time I discussed about some kind of problem / damage that has to do with screen CRT.
Filament WITH SHORT CATHODE / HEATER
When this happens, the display will show the color that is not normal, loss of one or two primary colors (RGB), Also if any one color dominant over the other and in accompanied Blanking lines.
It is important to be sure the difference between damage to the CRT or the RGB block circuit.
We can use a tool called CRT Restorer GUN (gunner crt / screen) ready pakai.tapi these tools are relatively expensive for most technicians.
Here I try to give some tips based on my experience on the desk.
To overcome this problem in which one leg of the heater cathode short (this causes the short to ground as well, because the heater supply lines associated with ground lines on FBT).
The solution is of course we have to separate the heater supply lines to the ground, how? course by providing separate paths for heater.Dari Suplly where? not possible we use another transformer for heater voltage.
You do this by utilizing more of the functions of FBT, because it is a transformator.Untuk FBT get extra voltage of the FBT is simply by wrapping a few rolls of wire / cable to the ferrite of FBT.hasilnya still a high frequency AC voltage, use a diode IN4007 and elco 100uF/50V to meratakannya.Pastikan earlier that the measured voltage which is approximately 6Volt by adding or subtracting the number of coils (usually between 2 to 4 wrap). Note that this circuit should not be at all related to TV channels on the PCB ground.
Disconnect the two heater lines on RGB pcb, and solder two wires to get to the circuit ini.Buat own place neatly.
This method has helped me in the case of SONY Trinitron CRT screen of either 29 "or 20".
ALTERNATIVE SCREEN SUPPLY
Screen alternative is a way to replace the function of abnormal FBT screen dim / bright or not can be set again for the glue permanently, is common in Polytron brand, Digitec, samsung etc.By default, the G2 (Screen) took the high voltage generated in the direction of FBT along with fokus.Keduanya voltage is set internally by resisitor and internal potensio to divide the amount of voltage that is suitable for Focus and Screen.G2 require large voltages between 500-100VoltDC, depending on of the characteristics of CRT.To be able to generate voltage instead of this, we can take from the collector point Transistor Horizontal out, because at this point there is tension between the TR and the oscillation is quite large FBT Circumference (around 1600v ACP-p). Because the current magnitude is relatively small for the G2 (only in size mA), it is safe for us to take a little current and voltage of sini.Pun this method also was applied by using the SONY Trinitron CRT.Use of high voltage diodes (recommended diode nuts). To flatten ini.Resistor 100 ohm voltage is simply as a barrier also fuse to prevent short on rangkaian.resistor and potentiometer divider is the relative size, but should be within the limits of the size of Mega ohms, you can replace value here to get the voltage diinginkan.Dulu distinguished in this way I apply many of the TV Digitec, Polytron, and some monitors.The circuit is very easy to make and can work well.
CRT RestorerCRT Restorer circuit here is useful to eliminate the leakage that occurred between the cathode-cathode RGB to G1.Jika Grid is the case then one or more colors will appear more dominant over the other, and the other colors look very weak / dim, can you measure / compare the three primary colors such stress on the position of the TV lights, the colors are dim would be measurable lower against the other colors.This is the result in the existence of very small particles (dust microscoptical) which inhibit the rate of electrons from the three CRT Electron Gun.The workings of this series is to provide a negative high voltage to the cathode RGB moment of this grid1.proses download the full right conditions of the CRT is still hot after the heater is activated prior to stepping electron becomes easy.This circuit configuration is to use a DPDT switch 4 position should be modified in advance to switch hit (no lock) with a view:
Consider the composition scheme ..
"Already in the revision"
When the switch is not in the press, diode rectifier fill elco 2.2 uF/350v, cathode and the G1 go to the circuit voltage of the transformer Vu meter.Dan 1amp go directly to the heater to heat.When the time switch in the press, Elco will be separated from the path of a diode and will spend its contents to the G1 leg while the foot 300V cathode towards the negative path. (Giving momentary voltage stored in elco), while the heater voltage of the transformer will be automatically disconnected (open). important to remember that during the filling process to the cathode voltage, heater voltage should drop out.Making this tool should be placed in a plastic box to avoid electric shock, use the legs RGB sockets used to create socket "prick" as many as 4 units, which do not use cable terlalukecil, to make the puncture handle, use a plastic straw from drinking mineral water (aqua ), cut into 3cm long, put the wires into the straw which has been cut and subsequently solderkan to foot former RGB socket, push the foot back into the RGB socket with the intention of straw as insulation as well as handles.How to use:1.Masukan two heater plugs cables2.Masukan pin plugs G1 to G1 in the CRT.3.Masukan foot CATHODE plugs into one of the legs of the suspected weak CRT / damaged4.Nyalakan the tool and wait until the heater on to warm up first5.Tekan DPDT switch, you notice there is a quick hop fire in the CRT, no problems, it is the process of cleaning the legs of the cathode, repeat until no more sparks a distinguished look.6.Lakukan again against another color cathode which are considered problematic, and do not in trying to press the switch on the cathode-come normal.dibolehkan if the suspect is less normal.7.kalau still not show the range of normal measurement meters, increase again with heater voltage selector switch (6V-7, 5v or 9V) to further heat up the heater, should be on trial at the lowest voltage positions first, then Rev voltage.As a rule how much deviation meter normal reply, can you try / compare the crt which is still good to be measured without knowl-charge-an.Tandai level.
Although I really like doing repairs crt which was dark with ini.Tapi not at the recommended tool for novices, because the risk of electric shock and rupture could have terjadi.Rangkaian heater is above the artificial orsinil ZICworkshop.Good luck and you will know the outcome.If at the time you work with this tool and does not work? .. Take it easy .. I think CRT is indeed already can not restore.I recommend to always try and use it as the best teacher ..
Original Source : zicelectronic
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