This time I will discuss about some kind of problems or damage that has to do with screen crt.
SHORT CATODE WITH FILAMENT / HEATER
When this happens, the display will display an abnormal color, missing one or two primary colors (RGB), Also if one of the dominant colors against another and accompanied the Blanking line.
It is important to be sure of the difference between damage to CRTs or on RGB circuit blocks.
We can use a tool called CRT RESTORER GUN (shoot crt / screen) ready to use. But the tool is relatively expensive for most technicians.
Here I try to give a little tips based on my experience at the desk.
To overcome this where the foot of one of the cathodes shorts to the heater (this causes short to ground as well, because the heater supply path is related to the ground path on the FBT).
The solution is of course we have to separate this heater supply line to ground, how to do? of course, by providing its own suplly line for the heater.From which? it is not possible we use the transformer again for the voltage heater.
The trick is to use more than the FBT function, because the FBT is a transformer. To get the extra voltage from the FBT is enough to wrap some wire / cable wire to the FERRIT part of FBT. The result is still a high frequency AC voltage, use diodes IN4007 and elco 100uF / 50V to flatten it. Be sure beforehand that the measured voltage is about 6Volt by increasing or decreasing the number of windings (usually between 2 and 4). Note that this circuit should not be at all related to the ground path on PCB TV.
Resolve both heater lines on RGB pcb, and solder two wires to get to this circuit. Make your own place neatly.
This has helped me in the case of SONY Trinitron CRT screens, both 29 "and 20
ALTERNATIVE SCREEN SUPPLY
An alternate screen is a way to replace the function of an abnormal bright FBT screen or brighter or irreversible because it has been permanently glueed, this is common in brands of polytron, digitec, samsung etc.
By default, G2 (Screen) takes the unidirectional high voltage generated from the FBT along with the focus voltage. Both are arranged internally by resisitors and internal potentios to divide the appropriate voltage quantities for Focus and Screen. G2 requires a large voltage between 500-100VoltDC, of CRT characteristics.
In order to generate this substitute voltage, we can take from the collector point of the horizontal out transistor, because at this point there is an oscillating voltage between TR and a large FBT winding (about 1600v ACp-p). Since the current current for G2 is relatively small (only in mA size), it is safe for us to take a little current and voltage from here. This method is also implemented by SONY using CRT TRINITRON.
Use a high-voltage diode (recommended peanut diode). To flatten this voltage. The 100 ohm resistor is solely a limiter as well as a fuse to avoid short occurrences. Resistors and potentiometers are relative in size, but must be within Mega ohm size limits, you can replace value here to get the desired voltage results.Dulu this way I apply a lot to TV digitec, polytron and some monitors.
This series is very easy to make and can work well.
CRT RESTORER
The CRT RESTORER circuit is useful here to eliminate the leakage that occurs between RGB cathodes on Grid G1. If this happens then one or more colors will look more dominant to the other, and other colors look very weak / dim, you can measure / compare the voltage of the three primary colors on the TV position lights up, ie the dim color will be measured lower against other colors.
This results in the presence of very small particles (microscoptical dust) which inhibits the electron rate of the three Electron Gun CRTs.
The way this circuit works is to provide instantaneous high voltages to the RGB cathode to the grid. This process lets the CRT state still hot after the heater is activated before to make the electron jump easy.
The configuration of this circuit is to use a 4 position DPDT switch which must be modified first into a push switch (not locked) with the intent
When the switch is not pressed, the rectifier diode fills the 2.2uF / 350v elco elco, the cathode and G1 leads to the Vu meter circuit. And the voltage from the 1amp transformer goes directly to the heater to heat.
When the switch is in press, Elco will be detached from the diode path and will drain its contents to the leg of G1 while the cathode feet toward the negative lane 300V. (Gives the momentary voltage stored in the elco), while the heater voltage of the transformer will be automatically disconnected (open). it is important to remember that during the process of charging the voltage to the cathode, the heater voltage must be broken.
Making this tool should be placed on a plastic box to avoid getting stunned, use the legs of a used RGB socket to make 4 "puncture" sockets, do not use the smallest cable, to make a puncture grip, use a plastic straw from mineral water (aqua ), cut as long as 3cm, input the cables into the cut straw and then solder them to the foot of the former RGB socket, push back the RGB sockets into the straw with the intention as an insulator as well as a handle.
How to use it:
1. Insert two cable plugs heater
2. Insert the G1 plug into the G1 pin in the CRT.
3. Put the foot plug KATODA to one of the CRT legs in the expected weak / damaged
4. Turn on this tool and wait until the heater turns on to preheat
5. Press the DPDT switch, at a glance you notice there is a fire jump in the CRT, no problem, it is the process of cleaning the cathode legs, repeat until no more sparks are visible.
6. Do it again to the other color cathodes that are considered problematic, and do not try to press the switch on the cathode which still normal.dibolehkan if the suspected less normal.
7. If still not showing the normal meter range, increase the heater voltage with the selector switch (6V-7,5v or 9V) to further heat the heater, should try at the lowest voltage position first, then boost the voltage.
As a benchmark of how much the normal meter deviation, you can try / compare on crt which is still good to be measured without doing penge-charge-an.Tandai level.
Although I really like doing crt repair that is dark with this tool. But not recommended for beginners, because the risk of stun and heater is broken can happen. The above series is orsinil artificial ZICworkshop.
Good luck and you will know the results yourself.
If at the time you work with this tool and unsuccessful ??? .. just cool .. I think the CRT is already can not be restored.
I suggest always try and use as the best teacher ..
SHORT CATODE WITH FILAMENT / HEATER
When this happens, the display will display an abnormal color, missing one or two primary colors (RGB), Also if one of the dominant colors against another and accompanied the Blanking line.
It is important to be sure of the difference between damage to CRTs or on RGB circuit blocks.
We can use a tool called CRT RESTORER GUN (shoot crt / screen) ready to use. But the tool is relatively expensive for most technicians.
Here I try to give a little tips based on my experience at the desk.
To overcome this where the foot of one of the cathodes shorts to the heater (this causes short to ground as well, because the heater supply path is related to the ground path on the FBT).
The solution is of course we have to separate this heater supply line to ground, how to do? of course, by providing its own suplly line for the heater.From which? it is not possible we use the transformer again for the voltage heater.
The trick is to use more than the FBT function, because the FBT is a transformer. To get the extra voltage from the FBT is enough to wrap some wire / cable wire to the FERRIT part of FBT. The result is still a high frequency AC voltage, use diodes IN4007 and elco 100uF / 50V to flatten it. Be sure beforehand that the measured voltage is about 6Volt by increasing or decreasing the number of windings (usually between 2 and 4). Note that this circuit should not be at all related to the ground path on PCB TV.
Resolve both heater lines on RGB pcb, and solder two wires to get to this circuit. Make your own place neatly.
This has helped me in the case of SONY Trinitron CRT screens, both 29 "and 20
ALTERNATIVE SCREEN SUPPLY
An alternate screen is a way to replace the function of an abnormal bright FBT screen or brighter or irreversible because it has been permanently glueed, this is common in brands of polytron, digitec, samsung etc.
By default, G2 (Screen) takes the unidirectional high voltage generated from the FBT along with the focus voltage. Both are arranged internally by resisitors and internal potentios to divide the appropriate voltage quantities for Focus and Screen. G2 requires a large voltage between 500-100VoltDC, of CRT characteristics.
In order to generate this substitute voltage, we can take from the collector point of the horizontal out transistor, because at this point there is an oscillating voltage between TR and a large FBT winding (about 1600v ACp-p). Since the current current for G2 is relatively small (only in mA size), it is safe for us to take a little current and voltage from here. This method is also implemented by SONY using CRT TRINITRON.
Use a high-voltage diode (recommended peanut diode). To flatten this voltage. The 100 ohm resistor is solely a limiter as well as a fuse to avoid short occurrences. Resistors and potentiometers are relative in size, but must be within Mega ohm size limits, you can replace value here to get the desired voltage results.Dulu this way I apply a lot to TV digitec, polytron and some monitors.
This series is very easy to make and can work well.
CRT RESTORER
The CRT RESTORER circuit is useful here to eliminate the leakage that occurs between RGB cathodes on Grid G1. If this happens then one or more colors will look more dominant to the other, and other colors look very weak / dim, you can measure / compare the voltage of the three primary colors on the TV position lights up, ie the dim color will be measured lower against other colors.
This results in the presence of very small particles (microscoptical dust) which inhibits the electron rate of the three Electron Gun CRTs.
The way this circuit works is to provide instantaneous high voltages to the RGB cathode to the grid. This process lets the CRT state still hot after the heater is activated before to make the electron jump easy.
The configuration of this circuit is to use a 4 position DPDT switch which must be modified first into a push switch (not locked) with the intent
When the switch is not pressed, the rectifier diode fills the 2.2uF / 350v elco elco, the cathode and G1 leads to the Vu meter circuit. And the voltage from the 1amp transformer goes directly to the heater to heat.
When the switch is in press, Elco will be detached from the diode path and will drain its contents to the leg of G1 while the cathode feet toward the negative lane 300V. (Gives the momentary voltage stored in the elco), while the heater voltage of the transformer will be automatically disconnected (open). it is important to remember that during the process of charging the voltage to the cathode, the heater voltage must be broken.
Making this tool should be placed on a plastic box to avoid getting stunned, use the legs of a used RGB socket to make 4 "puncture" sockets, do not use the smallest cable, to make a puncture grip, use a plastic straw from mineral water (aqua ), cut as long as 3cm, input the cables into the cut straw and then solder them to the foot of the former RGB socket, push back the RGB sockets into the straw with the intention as an insulator as well as a handle.
How to use it:
1. Insert two cable plugs heater
2. Insert the G1 plug into the G1 pin in the CRT.
3. Put the foot plug KATODA to one of the CRT legs in the expected weak / damaged
4. Turn on this tool and wait until the heater turns on to preheat
5. Press the DPDT switch, at a glance you notice there is a fire jump in the CRT, no problem, it is the process of cleaning the cathode legs, repeat until no more sparks are visible.
6. Do it again to the other color cathodes that are considered problematic, and do not try to press the switch on the cathode which still normal.dibolehkan if the suspected less normal.
7. If still not showing the normal meter range, increase the heater voltage with the selector switch (6V-7,5v or 9V) to further heat the heater, should try at the lowest voltage position first, then boost the voltage.
As a benchmark of how much the normal meter deviation, you can try / compare on crt which is still good to be measured without doing penge-charge-an.Tandai level.
Although I really like doing crt repair that is dark with this tool. But not recommended for beginners, because the risk of stun and heater is broken can happen. The above series is orsinil artificial ZICworkshop.
Good luck and you will know the results yourself.
If at the time you work with this tool and unsuccessful ??? .. just cool .. I think the CRT is already can not be restored.
I suggest always try and use as the best teacher ..
1 Komentar untuk "Trick fixing short cathode with filament / heater"
I would like to say that this blog really convinced me to do it! Thanks, very good post. Murrieta Water Heater Repair