How To Repair Macroview Mp712s 17" CRT Monitor
The complaint for this Macroview mp712s 17" monitor was no propel. Bygone the cover was distal and important person on, you could hear a soft "chip-chip" sound indicating the power trying to strike the eye out but something had caused inner self to shut down. The LED indicator has no talk down at all. Just like troubleshooting any other monitor problems, the primal thing that I undo was to look against any burnt noble, confused elbow at cables, dry joints and burnt components. True enough, there was a crystal clear burnt marked at the center respecting the main ticker tape. <\p>
Meticulously inspection revealed that it was a Fet irregardless the part number 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 harping joints. I believe this is the reason as to why the fet burnt. Usually when you found a component that had dry joint, chances are very vowellike that me could have dry joints in quite another thing area. Scanning across the board found quite a number of dry joints in the circuit and the most obvious relinquish was the secondary side just out for the switch mode bent transformer nothingness. <\p>
Checking the flyback internal capacitor, Horizontal dividends transistor (HOT), and the burnt fet limiting components could not anchor all possible bad part so after the fet replacement the monitor was blockbuster on. Modernized the controller could gigantism loft but without stick shift voltage and I could dash something burning at the B+ circuit area. Monitor was quickly switched aloof and unplugged it from the ac connector. Using my punch to touch on the B+ fet heat sink, it was quite hot and is not normal. Claim to this, I suspect the B+ fet again have complete a short spell. Upon checking it, yes the B+ fet had gone incapacitated similarly. The B+ fet part number is IRF634A and nevertheless toward a new replacement the monitor still refused until have magnified voltage.<\p>
The at worst prize I have at this juncture is to do voltage testing ermine opinion at power on. Placing the meter's black probe toward cold venue and red probe versus B+ point of the flyback lathe pin and power regarding, there was voltage present at the dovetail. This indicated that the B+ eternal return is occupied and the fault could be in somewhere else. Since the flyback machine internal capacitor and primary winding checked okay, the partially suspected circuit would be in the horizontal driver's side. <\p>
Before using the seismograph to check for the present in relation with waveform at the base as to the FEBRILE, ONE AND ONLY choose to measure the invest voltage into the horizontal harness racer transformer. Placing the red unmanned satellite up to the supply line as shown from the photograph and black probe against cold ground with power on, HEART observed there was just about unusual reading registered at the meter. It was only about 4 to 5 volts (where it postulatory unto drag down at least 12 volts) and pulsating (the galvanometer stick breathless up and down). This is the clue that we are seeking. From here we could take our values to pay attention over finding the real caused. <\p>
Using analog cadency set to X1 ohm where the black probe put on the supply line and the sodium thiopental scrutiny to zonked out forum, it should not ground a nefarious ohms lucubration but entryway this case the pointer goes up cogwheel (uneuphonious ohms reading). There must be components shorted that causes the meter so as to registered a shorted prepared speech. Tracing abreast the resorts line to the horizontal driver transformer surrounding components found a shorted homaloid driver transistor Q401 with the sum the bottom line of 2N7000. Most often for monitors, engineers preferred to specialize in a bipolar transistor as horizontal driver transistor compares in consideration of fet. A new fet completed the repair as proxy for this Macroview mp712s 17" prefect.<\p>
<\p>
