Repairing the Philips 104S
( Disclaimer: The procedure mentioned below involves some risk factor. You may do it at your own risk. I am in no way responsible for any damages or accidents occurring during the process. Some wires carry dangerously high voltages.) |
Objective : To screw up (repair) my faulty PC monitor (else it will a part of e-waste !! ) Requirements : Soldering iron , multimeter , schematic. Symptom : Only a horizontal line can be seen , as in the picture below. |
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Probable
reason :
Since there is horzontal line
seen on the screen , the horizontal deflection/scanning side is working
fine. The problem is with the vertical scanning / deflection section |
| Inside View |
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| Step 1 : Go through the schematics and find the vertical deflection section. I found that the monitor uses an I.C TDA 4860 as the vertical deflection amplifier. I found the IC on the PCB along with some burnt resisors nearby. The resistors were low value (2.2 ohm) given for safety puropse. A clear intication of a burnt IC. |
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| The IC TDA 4860 on a heat sink along with a burnt resistor |
| Step 2: After a time consuming and tedious search for the I.C , my friend got me one..The resistors were locally available. I replaced the IC and resistors and what i found was a bit surprising ! Have a look..... |
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Step
3 : The upper half of the screen(picture)
is visible while the lower half is blank !! . I had no idea what went
wrong. During repair i had tampered the ring magnets used for adjusting
convergence , puncusion etc.First i thought this could be the reason.But
even after trying different alignments, nothing worked out. I decided
to check the pin voltage of TDA4860 and found that a required negative
potential is missing at pin 6.While tracking from the pin, i found one
more burnt resistor at a corner of the PCB. Now what left was to replace
the resistor and the result was encouraging.............. |
Result : Obvious from the pictures below
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| Note Added, 2007 : No longer use the CRT , Using Samsung SyncMaster 540N LCD |
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| Note Added, 2010 : Using Dell D1920 19" LCD |
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