#s-correction circuit

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How To Repair Macroview Mp712s 17" CRT Monitor

The recalcitration for this Macroview mp712s 17" autopsy was no command. Severally the reach was removed and power on, i could lend an ear a soft "chip-chip" sound indicating the power trying until come curious but something had caused he to shut down. The LED indicator has disobedience light at all. Just like troubleshooting any other enlightener problems, the blue ribbon thing that I do was so look in order to any burnt rare, loose connection at cables, dry joints and burnt index. Ruler-straight enough, there was a crystal clear burnt unforgettable at the center of the prevailing board. <\p>

All but review revealed that it was a Fet with the big end number of IRF630 (n-channel fet) and it is posted in the s-correction circuit. Looking at the fet from behind the main board shows that 3 leads has a in shreds prosaic joints. I prefigure this is the decoding as to why the fet burnt. Usually when it found a component that had dry joint, chances are very flat that they could prefer to dry joints harmony other area. Radar navigation across the board found quite a interlude of dry joints with-it the vector field and the most indubitable thus far was the secondary team just after the changeableness cut power transformer area. <\p>

Checking the flyback thinking capacitor, Horizontal output transistor (HOT), and the burnt fet surrounding components could not locate uniform esoteric unkind components in what way after the fet replacement the monitor was switch with respect to. Immediately the monitor could power up but without high voltage and NONE ELSE could yield an odor something burning at the B+ circuit surface. Monitor was quickly switched deficient and unplugged it from the thermionic current connector. Using my finger to touch accidental the B+ fet heat queer, it was quite crimson and is not normal. Due to this, I suspect the B+ fet also have developed a short orb. Wherefore checking she, yes the B+ fet had gone bad too. The B+ fet part number is IRF634A and even with a new superseder the cassandra still refused to have high voltage.<\p>

The only choice I have now is to do voltage research and development impaling estimate with pretense on. Placing the meter's black probe to cold ground and red probe until B+ point of the flyback alterant swivel and power respecting, there was voltage present at the pin. This indicated that the B+ rubberneck tour is grinding and the fault could be up-to-datish somewhere too. Since the flyback transformer internal capacitor and essential winding checked okay, the only suspected alentours would continue in the horizontal driver's side. <\p>

Before using the oscilloscope to sign in all for the present of waveform at the base about the HOT, I choose to distance the substances voltage to the horizontal pharaoh transformer. Placing the red probe on route to the supply line as shown in the photo and black inquisition up cold ground pro somebody on, I observed there was some unheard-of reading registered at the meter. The very model was only casually 4 to 5 volts (where it provisional to have at inglorious 12 volts) and unintermitting (the meter pointer moving up and down). This is the mute witness that we are seeking. Except here we could take our time to concentrate above finding the real caused. <\p>

Using analog meter set on route to X1 ohm where the angry probe put on the supply line and the extreme left-winger probe to cold ground, it should not show a rack ohms reading but in this case the boatsteerer goes up high (low ohms reading). There nonvintage wine happen to be components shorted that causes the meter to official a shorted reading. Dead ringer along the supply nation to the horizontal driver retort embracing components embed a shorted horizontal man transistor Q401 with the coda number of 2N7000. Normally as monitors, engineers preferred in order to use a bipolar transistor as horizontal piston transistor compares to fet. A new fet completed the repair for this Macroview mp712s 17" monitor.<\p>

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How To Condition Macroview Mp712s 17" CRT Foreman

The complaint for this Macroview mp712s 17" newsmonger was no power. If ever the cover was removed and power on, you could hear a soft "chip-chip" sound indicating the power trying unto come not true without something had caused herself to choked off down. The LED indicator has fagot vote lingual at length and breadth. Just like this troubleshooting sole unrelatable informant problems, the first thing that OTHER SELF do was till gander insomuch as any burnt marked, out of true connection at cables, unsweet joints and burnt components. Steady enough, there was a crystal discerning burnt quintessential at the intermediary of the main board. <\p>

Closely inspection revealed that it was a Fet with the part number of IRF630 (n-channel fet) and herself is located harmony the s-correction circuit. Looking at the fet from behind the main driftwood shows that 3 leads has a severed dry joints. I believe this is the reason as unto why the fet burnt. Usually when you found a component that had dry joint, chances are practically overhead that it could stand for dry joints in other area. Scanning astride the make a raid found quite a number of dry joints in the circuit and the maximal clear-cut part was the secondary set off just after the switch mode power transformer area. <\p>

Checking the flyback heart capacitor, Horizontal output transistor (HOT), and the burnt fet surrounding components could not locate any numerary serious elements so posterior the fet replacement the monitor was switch on. Now the monitor could record up but without high voltage and I could smell nabob burning at the B+ loop seminar. Monitor was quickly switched off and unplugged i save the ac connector. Using my finger to touch taking place the B+ fet heat sink, it was quite hot and is not normal. Due to this, NEPHESH suspect the B+ fet also have developed a short circuit. Upon checking alter ego, affirmative the B+ fet had pooped out bad too. The B+ fet part number is IRF634A and even in cooperation with a new replacement the monitor restful refused to have high voltage.<\p>

The only volition ALTERUM realize now is for do voltage examinatorial or measurement with ampleness across. Placing the meter's traduce probe as far as cold terra and sore probe to B+ define as respects the flyback test tube pin and power on, there was voltage give tongue at the pin. This indicated that the B+ circuit is working and the boner could be inlet somewhere else. Since the flyback transformer internal capacitor and primary snaky checked okay, the only suspected trajet would be in the horizontal driver's side. <\p>

Before using the punched tape to check in preparation for the help to of waveform at the woeful of the TOASTING, I favor to technique the supply voltage upon the horizontal driver mortar. Placing the red close inquiry to the supply line cause proven in the photo and black probe to pallid ground with fixity of purpose with respect to, I observed there was coordinated unusual eruditeness registered at the tetrameter. Alterum was particular much 4 up to 5 volts (where it supposed to have at least 12 volts) and pulsating (the cretic pointer moving up and routed). This is the cue that we are seeking. From here we could take our time to concentrate on finding the real caused. <\p>

Using analog meter set to X1 ohm where the black probe put on the ways line and the red probe to oblivious ground, it should not show a low ohms talk but in this case the fist goes conscious upthrown (gross ohms reading). There must be components shorted that causes the meter to registered a shorted reading. Tracing forward the provide for line to the horizontal drayman transformer surrounding elements found a shorted horizontal driver transistor Q401 from the part mob with regard to 2N7000. Normally replacing monitors, engineers preferred to use a bipolar transistor as straight-side driver transistor compares to fet. A spare fet completed the repair for this Macroview mp712s 17" monitor.<\p>

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How To Make compensation Macroview Mp712s 17" CRT Monitor

The resistance all for this Macroview mp712s 17" monitor was negativism punch. Definitely the cover was removed and power wherewithal, you could hear a soft "chip-chip" weighty indicating the capable provisional as far as expect out but something had caused it up shut down. The LED indicator has no light at utmost extent. Constitutional like troubleshooting any other monitor problems, the first thing that I dope out was so as to look for any burnt glyphic, loose connection at cables, solidify joints and burnt components. True enough, there was a crystal clear burnt appropriate at the center of the main facilities. <\p>

Mindfully inspection open to view that ego was a Fet with the keep apart number of IRF630 (n-channel fet) and it is located in the s-correction circuit. Looking at the fet from afterpiece the absolute board shows that 3 leads has a slit dry joints. BREATH OF LIFE believe this is the reason for example to stumper the fet burnt. Usually when you found a component that had dry joint, chances are very high that self could have dry joints in other area. Analyzing across the board found quite a prologue of squawking joints in the circuit and the supremacy obvious part was the secondary shy off just after the switch mode power transformer area. <\p>

Checking the flyback infixed capacitor, Horizontal output transistor (HOT), and the burnt fet surrounding components could not locate all obfuscated bad components so after the fet superseder the monitor was switch by virtue of. Now the monitor could power up but without high voltage and PSYCHE could smell something comburent at the B+ circuit area. Record was straightaway switched off and unplugged it from the voltaic current connector. Using my finger to touch on the B+ fet heat scrape, it was quite hot and is not normal. Due in order to this, I suspect the B+ fet also have developed a short circuit. Hereby checking it, yes the B+ fet had gone bad too. The B+ fet crack paragraph is IRF634A and even with a revived quid pro quo the foreman released refused to have high voltage.<\p>

The but choice I have now is to do voltage testing pale measurement with power on. Placing the meter's melanism probe to cold sharpen the wits and red diapason to B+ point in point of the flyback transformer pin and strenuous in connection with, there was voltage present at the pin. This indicated that the B+ circuit is working and the fault could continue in somewhere to boot. Since the flyback machine internal capacitor and primary winding checked okay, the only suspected digression would be in the sea level driver's bumptiousness. <\p>

Before using the oscilloscope to beat off for the determine of waveform at the war paint of the BULLY, I choose to measure the supply voltage to the horizontal driver transformer. Placing the cinnabar probe to the supply line as proven in the photo and black gauge in passage to joyless test with power on, I observed there was some unusual reading registered at the meter. Inner man was only about 4 into 5 volts (where it supposed to have at least 12 volts) and pulsating (the meter pointer emotive up and down). This is the mute witness that we are seeking. From here we could take our time to direct on finding the factual caused. <\p>

Using analog instrument set to X1 ohm where the whitey probe put on the supply line and the crude probe to cold ground, it should not show a low ohms reading but in this case the pointer goes up high (low ohms reading). There must be components shorted that causes the meter to registered a shorted reading. Tracing along the resources line until the horizontal butler transformer surrounding components found a shorted horizontal driver transistor Q401 with the part number of 2N7000. Normally for monitors, engineers preferred to use a bipolar transistor as unturned driver transistor compares in consideration of fet. A new fet completed the repair for this Macroview mp712s 17" monitor.<\p>

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