Text preview for : inverter_modification_748.pdf part of Phillips 42PFL7422D/37 This is the repair/mod for the inverter card.
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LG inverter modification "II"
Ref. nr. SCC_73709 Doc. version 1.2 October 30, 2009
SCC_73709
COMPONENT KIT (996500095005)
The Component Kit includes the following components (for Master & Slave) : · TVS zener diode (33 V) · MLCC capacitor (100 pF) · Resistor (DIP type or SMD) 4.7 x2 x2 x4
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STEP 1
Confirm Inverter model name:
·PNEL-T707A(MASTER), ·PNEL-T708A(SLAVE).
REMARK 1
· It does not matter if the zener diode (modification "I") exists or not for inverter modification "II".
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STEP 2.1
Cut tracks: - Cut the SW1 & SW2 tracks on both inverters. - Confirm that there are no short circuits with metal pieces of tracks, and there is no damage to other tracks !
PNEL-T707A
PNEL-T708A
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STEP 2.2
1. Check the secure cut line (SW1 & SW2) by visual inspection first:
Visual inspection to verify if cut well and not damaged.
2. Check the resistance between two `via' holes of the cut SW line:
Measure the resistance of the cutted SW1 & SW2 line through ,,via holes with a DVM (Digital Volt Meter).
Measure Point (Master)
Cut Mark
Measure Point (Slave)
Case 1 > Several tens of k: Line cut well. Case 2 > under 1 : Line short. After attaching the resistor, the resistance should be 4.2 ~ 5.2 .
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STEP 2.3
Check pattern damage of parallel tracks
Cut Mark
Cut mark
PNEL-T707A
GND
PNEL-T708A
GND
GND
GND
SW1 Pattern SW2 Pattern HN2 Pattern SW1 Pattern HN1 Pattern HN1 Pattern HN2 Pattern SW2 Pattern
Case study for pattern damage of parallel tracks
Parallel tracks of SW line are HN1, HN2 and GND tracks. - Case1> If cut the HN track by mistake Cause of Inverter malfunction. Check : HN lines resistance should be under 0.5 when measured with DVM (resistance b.t.w. via holes of HN line). - Case2> Damage on GND track by mistake No affect to Inverter function. No damage on GND function because GND track is spread widely.
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REMARK 2
· The kit of components can include the following resistors:
4 x DIP type resistors (4.7 ) with shrink tube (20 mm) then go to step 3.1 and 3.2
20mm
OR 4 x SMD type resistors (4.7 ) then go to step 3.3
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STEP 3.1
Solder resistors on board PNEL-T708A: - Remove the coating/varnish on solder point to reveal the copper pad. - Solder resistor (DIP type resistors (4.7 ) with shrink tube (20 mm)) on solder points (red marks).
PNEL-T708A PNEL-T708A
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STEP 3.2
Solder resistors on board PNEL-T707A:
- Remove the coating/varnish on solder point to reveal the copper pad. - Solder resistor (DIP type resistors (4.7 ) with shrink tube (20 mm)) on solder points (red marks).
PNEL-T707A PNEL-T707A
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REMARK 3
Front side of reworked inverter (DIP type resistor):
DIP type resistor (Front)
Side view dimension of implemented inverter
Take care that the height of the DIP type resistor is below the height of the transformer because of the metal shielding on the inverter boards.
Trans. Resistor 8mm 3.5mm 3.5mm Cover Bottom 1mm Shield Cover
Cap. 11mm
10.1mm
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STEP 3.3
Solder SMD resistors on board PNEL-T707A and PNEL-T708A:
- Remove the coating/varnish on solder points to reveal the copper. - Solder SMD resistor on created solder pads (red marks).
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STEP 3.4
Solder capacitor (MLCC) on PNEL-T707A and PNEL-T708A:
-Solder capacitor MLCC (100 pF) on blue indicated position.
MLCC position
PNEL-T707A
PNEL-T708A
PNEL-T707A
PNEL-T708A
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STEP 3.5
Solder zener diode (TVS) on PNEL-T707A and PNEL-T708A:
- Solder zener diode TVS (33 V) on red indicated position.
Classification
Polarity TVS position Non polarity
Indication
Band mark on body No mark
Attachment
Place band mark on assigned position No need to distinguish the TVS direction
PNEL-T707A
PNEL-T708A
Polarity : Band mark position Non-Polarity: No placing direction
PNEL-T707A
PNEL-T708A
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