QSC K8 - Line Filter - Broken Components (BOP)

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TD-000487-00
K Series Service Manual
9.2 Line filter - broken components (BOP)
PCB flex/vibration issues seem to cause more broken-component failures in the K12 than in the other K Series models.
Most common are component leads that break between the base of the component and the PCB. Most vulnerable are the
heavier components, such as ferrite-core inductors, located in the AC line filter. Fortunately, these failures usually cause no
collateral damage to other electronics, though in some rare cases, arcing could burn the PCB and the whole PCB assembly
would need to be replaced.
Symptoms:
• no power or intermittent power cycling
• turns off while playing audio, especially at peak levels
Failure verification:
• any one broken lead on any component listed in the table below
Repair notes:
• Check every single component in Figure 9.5 and the table below for
lead breaks.
• Check all leads on the components for breaks. Any of them could
potentially break.
• If you find one of the components has a broken lead, there is a
good chance that a second component also has one.
• Heat the leads from the underside of the board with a soldering iron to check for lead breaks. A broken lead will simply
float away when solder is applied to it.
• To check for intermittence, it’s recommended to remove the amplifier module from the speaker enclosure, apply AC
power through the IEC jack, turn the amplifier module on, and gently hit the amplifier module with a rubber mallet or
hammer. (Figure 8.5).
Reference Description QSC Part #
L13 Inductor 774 µH, 2 pin XF-000377-00
L11, L12 Inductor 4 mH 4 pin XF-000376-00
R140 NTC resistor 2.5W RE-000300-NR
T2 Transformer XF-000362-00
Figure 9.6 - Heating up a lead on inductor L11.Figure 9.5 - Components to heat up with solder and check for
lead breaks
Figure 9.4 - One lead broken on inductor L12