These 17 "CRT Relisys OEM Monitor came with the complaint of dark display (can not see back raster). Although the front panel through the On Screen Display (OSD), you must set up the grid and back again does not show the 'whole display appeared quite dark. Usually when we dim the display problem of this type can be seen directly to the flyback and the regular' (G2), voltage regulation screen for increased tension on the tube in so that theThe display is bright again.
Somehow, in some developed CRT monitor, there is (G2) control screen (Button) for you to adapt. It contains only two buttons to adjust the focus (F1 and F2). Since it can not determine, the G2-control would flyback, you always have the preset brightness control for internal research, but unfortunately this model is not. It only has the B + control and high voltage pre-control. The preset voltage stuck highSilicon, and we simply do not agree otherwise, the default, the monitor intermittently goes into shutdown mode. The only requirement is to adjust the B + control. Yes, it is true that in order to monitor some, you can preset tune the B + control to increase the brightness, but is not recommended increasing the B + voltage increases the load on the horizontal output transistor (HOT). The heat does not last long, and sometimes blow up in a few hours.
In thisMonitor, I tried to adjust the B + presets to see if the light appears or not, but the result has caused the display to go wider and still dark. If I continue to tune the B + control, I fear, the HOT may blow in a very short time! This is just an experiment, but that does not correspond to the B + control without a good reason.
After the power has been used for several years was the CRT cathode (emission) have become weak and this has caused in the dark display. AThe display is bright again, you can increase the heating voltage of 6.3 volts to about 8 to 9 volts. Or you can use the G2 circuit to preset the tension without any adjustment or high voltage B + to increase the monitor. In this article I'll just change the circuit G2.
Since the flyback is not the G2-control so that we can not look out of the line flyback trace for the G2. In fact, we can trace back from the CRT board on where to seeG2 came wire. Yes, he came from the motherboard and not the flyback. When he turns back the motherboard, you can easily G2 including a small circuit, high voltage capacitor and a diode from a few ohms resistance very high.
This is the way to work the circuit G2. The high pulse came from an AC power of the flyback transformer secondary and the pins that pass through the ultra-fast recovery diode. The function of the diode is to convert the drive to high voltage alternating current, highCondenser (102 2kV ceramic-resin-type) is used to filter the high frequency waves and thus the power flow is determined by the resistance and the resistance (set) the output voltage. Once you know how this circuit, you can easily modify the circuit or change the value of resistance, the G2 can increase the tension.
From the picture you can clearly see that by removing the jumper and added, were in a 4.4 mega-ohms (2.2 M in series with one another the result of 2.2 Mof 4.4 M ohms) I was able to slightly increase the voltage of G2. You may ask, "How do you get the value of 4.4 M?" In fact, before I tried some high-ohm resistance values from 100 K and then 1 M 2.2 M Then I conclude that 4.4 million ohms, the best display (brightness) have. If you remove the jumper (link) will display is too bright and not good for you.
In some models able to monitor the voltage of G2 the highest value, and when this happens, resistance to change, no matter what value orChange in output voltage of the circuit, the G2 is always the same, because the voltage is already the highest in G2. It is only possible in the lower G2 voltage and no way to increase the tension G2! If this happens, then you need to change the filament voltage to increase the brightness.
Conclusion-In fact, any electronic circuit, if you really understand how a particular circuit to work, you may actually need to make some changes to the electronic devices to work again. When the electronicEquipment is beyond repair, there is no harm in trying any change in method that you think is the best in the electronic device can return to work. To do this, you need to equip a basic knowledge of electronic theory have. For your information, this dilemma is a common mistake, and I've solved a lot of it and made some nice income from a mere 10 minutes of work. Have a great day my friend!
