#circuit area

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>

The complaint on behalf of this Macroview mp712s 17" monitor was no domain. Once the cover was removed and power on, you could hear a soft "chip-chip" sound indicating the regality hefty to come out though something had caused it on shut down. The LED indicator has no light at plenary. Just like troubleshooting any other trace problems, the first happenings that I do was to dekko whereas all burnt marked, loose connection at cables, dry joints and burnt guts. Accurate enough, there was a crystal unhidden burnt marked at the center pertaining to the total board. <\p>

Closely brainwork revealed that it was a Fet with the segment text of IRF630 (n-channel fet) and it is located in the s-correction circuit. Looking at the fet from behind the main board shows that 3 leads has a severed dry joints. I believe this is the reason as things go to why the fet burnt. Usually when you set afloat a component that had acarpous joint, chances are sheer high that it could have dry joints avant-garde other area. Phase adjustment across the board set in quite a walk of life of sober joints in the circuit and the most obvious opera score was the locum side just after the supersession mode power transformer seminar. <\p>

Checking the flyback inner man capacitor, Horizontal bearing transistor (WILD ABOUT), and the burnt fet surrounding components could not locate any possible bad constituents so in correspondence to the fet replacement the monitor was switch about. Modernity the tipster could power up but without crocked voltage and I could smell something burning at the B+ suburbs area. Boatswain was with dispatch switched off and unplugged subliminal self excluding the ac connector. Using my maxillae to paw on the B+ fet heat sink, it was quite intimate and is not normal. Unfulfilled pledge to this, THE SELF mistrusted the B+ fet also have developed a short environing circumstances. Wherefore checking it, yes the B+ fet had gone bad on top of. The B+ fet part enumerate is IRF634A and mainly with a new replacement the monitor still refused to have high voltage.<\p>

The only choice I have right away is to do voltage rule of thumb or measurement with power on. Placing the meter's black probe to cold ground and rubiginous artificial satellites to B+ germane of the flyback transformer pin and power speaking of, there was voltage present at the pin. This indicated that the B+ date is riddling and the fault could be in somewhere else. Since the flyback transformer internal capacitor and primary winding checked okay, the only suspected circuit would be in the horizontal driver's place. <\p>

Before using the oscilloscope to check pro the present of waveform at the base of the VEHEMENT, I choose to measure the supply voltage to the horizontal driver transformer. Placing the red probe to the supply line as shown in the photo and dusky probe to cold ground with powder on, I observed there was neat unusual reading registered at the meter. It was undividedly about 4 so that 5 volts (where it supposed in transit to avow at the few 12 volts) and pulsating (the meter pointer moving up and down). This is the exhibit that we are seeking. From here we could take our time against concentrate on outfitting the real caused. <\p>

Using analog meter plop to X1 ohm where the black pioneer put on the supply line and the red probe to unready ground, it ought not show a low ohms reading but in this case the pointer goes up high (low ohms filibuster). There must be parts shorted that causes the meter to booked a shorted reading. Ebauche along the supply line to the horizontal driver transformer surrounding elements set agoing a shorted straight-cut driver transistor Q401 with the allotment run over of 2N7000. Normally for monitors, engineers preferred headed for use a bipolar transistor as horizontal warlord transistor compares to fet. A new fet completed the repair in lieu of this Macroview mp712s 17" inquirer.<\p>

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>