Dell D1626HT - UltraScan 1600HS - 21" CRT Display Service Manual

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Dell D1626HT - UltraScan 1600HS - 21" CRT Display Service Manual Manual pdf 18 page image

D1626HTSECTION 3SAFETY RELATED ADJUSTMENTWhen replacing or repairing the shown below table, thefollowing operational checks must be performed as asafety precaution against X-rays emissions from the unit.a) HV Regulator Circuit Check1) Confirm that the voltage of the pin 2 of CN901 on Dboard is within the voltage range shown below.Standard: 9.00 ± 0.065 VDCb) HV Protector Circuit Check1) Confirm that the HV protector circuit works and TVRaster disappears when apply the voltage as shownbelow between pin 3 of CN901 on D board andGND using an external DC power supply.Check Condition: Less than 34.10 VDCc) Beam Current Protector Circuit Check-11) Measure HV voltage and record that value.2) Shorted between pin 1 and pin 4 of CN901 on Dboard.3) Connect to the Constant Current Jig (A) between pin1 of CN901 on D board and GND, confirm that theBeam Current Protector Circuit works and HV godown more than 1.25 kV from the value of (1).Check Condition: 1.50 mAd) Beam Current Protector Circuit Check-21) Connect to the Constant Current Jig (B) between pin1 of CN901 on D board and GND, confirm that theBeam Current Protector Circuit works and TV Rasterdisappears.Check Condition: 1.59 mAe) Voltage of 3rd winding of FBT1) Confirm that the voltage of pin 3 of CN901 on Dboard is within the voltage range shown below.Standard: more than 28.0 VDCHV RegulatorCircuit CheckHV ProtectorCircuit CheckBeam CurrentProtector CircuitCheckPart Replaced (])D Board IC901, T902• Mounted D boardD Board Q660, Q661, D916,D935, C924, R665,R667, R940, R980,T902• Mounted D boardG Board PH680, Q680, Q683,D680, R680, R685,R686, R687, R688,R689• Mounted G boardD Board IC901, D904, D907,D908, R011, R908,R909, R921, R925,R926, R929, R930,T902• Mounted D boardCheck ConditionInput voltage : 100 ~ 240 VACInput signal : White Cross Hatch at 107 kHzBeam control : BRT and CONT → MinimumB+ voltage : 195 ~ 205 VDC