31
TD-000487-00
K Series Service Manual
9. Troubleshooting guide
9.1 General tips and tricks
Testing the line filter components for open circuit in two measurements
The components in the line filter (L11, L12, L13, R140, F1) and
the bridge rectifier (BR1) can all be checked in two measurements
taken from the top of the power/amp PCB.
With a DMM in diode-check mode, place the negative/black lead
on J14 (AC LINE) and the positive/red lead on PRI_HI (R147). If
the measurement reads normal (approximately 0.5 V) then there
are no obvious lead breaks. Next, place the positive/red lead on
J15 (AC NEUTRAL) and the negative/black lead on PRI_LO (R144).
Again, if the measurement reads approximately 0.5 V, then there are
no obvious lead breaks.
Note: This tip does not account for intermittent lead breaks that
can be discovered by applying solder to the leads on the bottom
of the board! Please read “9.2 Line filter - broken components
(BOP)” on page 33 for more info.
Testing the PSU/amplifier board without the input/DSP board
The PSU/amplifier board can operate without the input/DSP board connected because there is no PSU control or link
coming from the DSP. You can perform a quick test on the PSU/amplifier board. This is only a simple test to determine the
SMPS is switching and generating the main/auxiliary voltage rails. Follow the instruc-
tions below to test the PSU/amplifier PCB.
1. Disconnect AC power from the BOP.
2. Wait at least 5 minutes to allow the BOP to naturally discharge all capacitors.
3. Remove the faceplate assembly by following removal instructions in “7.1 Face-
plate” on page 23.
Warning: High voltage! The board must be mounted to the heatsink if being left
on for more than 10 seconds, or the MOSFETs will overheat and fail.
4. Connect AC wires to J14 (LINE brown) and J15 (NEUTRAL blue). We recom-
mend a custom IEC jack with brown/blue wires as pictured in Figure 9.2.
5. Apply 120 Vac (or 230 Vac if 120 Vac is not available) across the AC wires. If
possible, set current trip to approximately 3 amps for safety.
6. Take the following measurements and verify functionality.
Signal Name Best location
to measure
Reference Measurement (Vdc)
@ 120 Vac
Measurement (Vdc)
@ 230 Vac
PRI_HI R144 PRI_LO 164 V 308 V
VIN R147 PRI_LO 41 V 77 V
LINE_UV R189 PRI_LO 3.1 V 5.8 V
+VCC R174 GROUND 85 V 85 V
-VCC C33 GROUND -85 V -85 V
+15V D38 cathode GROUND 15 V 15 V
-15V D39 anode GROUND -15 V -15 V
VDD1 D28 cathode GROUND 8.7 V (no load) 8.7 V (no load)
Figure 9.2 - Powering up just the PSU/
amp board
L1 1
L12
L13
F1
R140
#2 - red probe
#2 - black probe
#1 - red probe
measurement #1 - black probe
Use diode check mode.
Should measure ~0.5V
Figure 9.1 - Quick check of line filter components
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