---------- Track: summa.fail.a.sleep...;) By: djz.hwc ---------- I somehow got a Gunfighter ega-monitor and I decided to connect it to Spec. With this purpose, the monitor was solemnly handed over me to conduct experiments on it and scientific research to identify the ability to connect it to the ZX. The monitor itself was quite small, with 15 inches, approx. When turned on showed signs of life in the form of a launch line scan unit. Unfortunately, there were no other signs of work. The screen was black, at least give it to this monitor of what, at least not. Therefore it was decided it was necessary to tighten the shortcut on the kinescope board (if I'm not mistaken, it regulates accelerating voltage). As a result it became possible to change these manipulations raster brightness from zero to uniform white. Unfortunately, without images and colors ;( Then it was decided to disassemble the hell with this monitor into its component parts, fortunately there everything is located on the chassis and connected connectors. True, with the quantity fasteningelements manufacturers clearly they overdid it and there were a lot of bolts a lot. As a result of the above actions The monitor was disassembled into its component parts: kinescope, board, power supply and housing. Unfortunately, enable it in this form turned out to be completely impossible, since connecting wires in many places were too short for all this connect in disassembled form. Therefore every time to check the performance of the monitor, its I had to put it back together ;) So, we look from the connector along r, g, b. Diodes and shortcuts are of little interest to us, although they are simply scribbled on these signals a huge variety. What do we see? PLM'ku in the crib and inverter After them - straight to the amplifiers and kinescope. The kinescope turned out to be working - this is the conclusion I made, one by one tearing off the wires coming from the terminals amplifiers for kinescope. Guns r, g and b worked great :) Then I decided to connect the ZX to the monitor and measure the amplitude of the output signals PLM'ki, i.e. at the terminal inputs video amplifiers. There was a signal there, and changed depending on what the picture should be on the screen. Therefore, the circuits up to the video amplifiers OK. This makes me extraordinary made me happy, although even ifthe whole tract amplification of these signals is burnt out, you can it would be easy to assemble an amplifier for each one or two transistors. This is not for us problem. So. It has now become clear that video amplifiers are faulty, and immediately all three ;) This got me thinking, that something is blocking them. Unfortunately, there was no circuit diagram for this monitor, and no blocking circuits in monitors, according to idea, it shouldn't be. Well... There is only one thing left - select one amplifier and check cascade after cascade. I must say The monitor is designed very interestingly - seven (!) transistors per amplifier... This, you know, is something :) Let's go along the first one cascade - the cascade is working, go to the final one - there is no signal. Therefore, middle. Gunfighter just came in here :) K fortunately, without beer ;) I must say, the presence of someone was not present during equipment repair stimulates my thinking abilities :) therefore, having received a pair from a friend advice, I continued checking the work cascades. Why check there if not? I have an idea about the scheme? Flipped through a book with diagrams TVs, paying attention to construction of final stages video gain. ANDнашел одну похожую схему:She was very similar, but this and it doesn't matter. But I understood how these amplifiers are built in this model monitor. Then everything became clear. By the way, it should be noted that between PLM'koy and video amplifiers (VA) stood another amplification stage, at the same time there the brightness was mixed. This canoe fed from a separate source voltage and was also working properly. Well... I turn on the monitor and climb probe through the terrifying appearance line scan circuits, like myself towering lineman and every now and then crackling wires ;) and I see that is on the terminals of one of the transistors. And what do I see? But I see a zero on the base, although in theory, there should be tension there, close to the feeder. - Take off the fee! - Gunfighter commands. We check for short circuit - and that’s it! Something short. We look along the paths and see large 470 µF capacitor, in the diagram it is highlighted and an arrow points to it. We solder it - and that’s it. To the capacitor cranks. What was unusually surprising Gunfighter :) With a proud look I take it out from my reserves domesticcapacitor of the same rating and voltage, only according to gabatiram one and a half times larger ;) and I solder it, having first straightened it nearby radio elements to the sides :) We can end here narration, since the main the fault has been corrected. Yes, I almost forgot - signals r, g and b must be fed to the monitor input directly from the control center. Now let's talk about how convert a similar ega monitor to svga! The prospect, I must say, is tempting, but due to my lack of ega'shnogo monitor for experiments, more I can't give detailed recommendations ;) I saw this technique on one of Internet sites for hardware... So, the most important thing is to increase monitor line frequency from 15 to 37 kHz. The second is to adapt the path video signal processing, which is due to digital input, not analogue, as in svga. To change the line you need to find defining string generator, and next to it - frequency-setting capacitor. Replace it (with small TKE) to a capacitor with lower denomination. Close the base and emitter of the output line transistor. To base connect the buffer transistoroscilloscope. Set the frequency to 31 kHz. Don't forget to check your parameters line transistor - necessary voltage about 1500 V, power 30 W and frequency from 30 MHz. Very desirable presence of built-in damper diode (2SCЗ883, BU2508, 2SCЧ769 are suitable). Now you can remove the jumper between base and emitter and connect to the gap power scan resistor type PEV on 10...20 W nominal 20 Ohm. Turn on the monitor. Possibly dim narrow picture. If there is a twist per screen, denomination required capacitor parallel to the output transistor (and the capacitor should be 1600V type K78-2 or similar). Then short-circuit the coil regulating size of lines that stands in the OS break and wind up half of the linearity regulator lines. In theory, a smooth line should appear, but narrow picture. Now we will raise line supply voltage scans. If the monitor has voltage 80-100V, then connect it instead of 55 and be sure to change it in the power supply diode along this line to a more powerful one (for example, KD226). After this, the size and brightness should normalize, but don't forget to drive monitor for overheating. If The line transistor gets very hot, install a radiatormore. 600 line mode in ega monitors it's quite easy to get since there frequency switching is 15/21 kHz (in the primary winding of the lowercase two transformers are switched windings). If the monitor is working normally and not overheats, can be removed limiting resistor and close the place where it breaks.
Pen - Monitor repair: I somehow got a Gunfighter ega-monitor and decided to connect it to Spec...
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