powersoft D-Cell 504 Service Manual
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© 2012 - 2013 Powersoft
powersoft_DCell504_servman_en_v1.2
service manual
D-Cell 504
REV 1.2 June 2013
Table of contents
1 Important safety instructions
3
2 Tools
3
3 Disassembly the power supply
4
4 Disassembly the amplifier board
4
5 Assembly outline
D-Cell 504 power supplies
5
6 Assembly outline
D-Cell 504 amplifier board
6
7 Checking the power supply
7
8 Failure of the varistor
7
9 Failure of the inductor
8
10 Checkng the output stage
8
11 Failure of the MOSFETs
9
12 Further tests
9
13 Spare part list
10
D-Cell 504
10
1 Important safety instructions
WE RECOMMEND THAT ALL SERVICE OPERATIONS ARE
CARRIED OUT BY A TECHNICIAN IN THE MANNER
DESCRIBED IN THIS GUIDE.
IF NOT EXPLICITLY STATED OTHERWISE, DISCONNECT
THE AMPLIFIER FROM THE MAINS BEFORE OPERATING
THE AMPLIFIER.
WARNING! INTERNAL CAPACITORS BANK COULD BE
CHARGED AND HARMFUL
This technical document is aimed to be a support guide in
solving the most recurrent failures of the D-Cell504 amplifier
modules.
The troubleshooting approach will help you characterize the
kind of fault you incur. A recovery method and the related assembly
outline detail is thoroughly explained for the most common faults.
The components to be replaced are clearly shown in red print
to help their identification. At the end of this guide you can find
a detailed list with the description and the respective Powersoft
internal reference code of the spare parts.
2 Tools
f
f Phillips PH 0 screwdriver.
f
f Phillips PH 1 screwdriver.
f
f Small cutter
f
f Tweezers
f
f Function generator or test CD + CD player.
f
f Double trace oscilloscope (it must be disconnected from the
ground) and probes.
f
f Multimeter.
f
f Soldering station.
f
f Mains insulation transformer/variac.
3
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
!
3 Disassembly the power supply
1. Remove the six top cover fixing screws
2. Carefully remove the PSU board from the heat
sink
4 Disassembly the amplifier board
1. Remove the six top cover fixing screws
2. Carefully remove the PSU board from the heat
sink
FIGURE 1: DC Power supply: remove six screws.
FIGURE 2: AC Power supply: remove six screws.
FIGURE 3: D-Cell 504 amplifier board: remove six screws.
4
5 Assembly outline D-Cell 504 power supplies
FIGURE 4: D-Cell 504 AC power supply.
FIGURE 5: D-Cell 504 DC power supply.
5
6 Assembly outline D-Cell 504 amplifier board
FIGURE 6: D-Cell 504 amplifier board - Top view.
FIGURE 7: D-Cell 504 amplifier board - Bottom view.
6
7 Checking the power supply
Evidence of a fault in the power supply stage is a
blown main fuse (located close to the main switch).
Before replacing it, check if the protection varistor is
also blown. If not, disassemble the power supply board
from the chassis and check all components as illustrated
in the following paragraphs.
If the protection varistor is blown, move on to the
next step regarding the varistor issue
8 Failure of the varistor
A varistor RV1 short circuit, resulting in its
permanent damage, can occur if a mains voltage higher
than 250VAC is applied to the D-Cell PSU. In this case
the main fuse is also always blown.
1. Components to be replaced:
f
f RV1 varistor
f
f F1 Fuse
We recommend anchoring the varistor with
silicone glue to the nearest capacitor.
FIGURE 8: Fuse.
FIGURE 9: Fuse on PCB.
7
9 Failure of the inductor
If the 47 µH inductor in position L835T should
fail, please replace it with a new inductor of the same
nominal value but with a maximum current tolerated
of 1.3 A. This specific power supply fault is present in
first series power supplies equipped with inductors
with an inadequate maximum current tolerance.
1. Components to be replaced:
f
f 47 µH inductor
We recommend securing the inductor to the
body of the coil with silicone.
10 Checkng the output stage
Hold the probes of a multimeter on the two fuses
in the secondary stage of the power supply, F800T and
F8001T. Then check in the AMP stage which of the
two channels has at least one MOSFET with the drain-
source junction short circuited
FIGURE 10: L825T inductor.
FIGURE 11: L825T inductor position on the PCB.
FIGURE 12: Output fuses on the PCB.
8
11 Failure of the MOSFETs
1. The MOSFETs are located on the bottom side of
the amplifier’s PCB.
2. Components to be replaced:
f
f Channel 1 MOSFETs Q200, Q201
f
f Channel 2 MOSFETs Q500, Q501
We recommend to carefully position the Sil-Pads to
ensure the proper heat exchange between the com-
ponents and the chassis.
12 Further tests
1. After checking and replacing all the defective
components, try to test the module applying an
incremental voltage through a variac.
2. Connect the probes of your multimeter to the
CN800T connector on the power supply board;
with respect to ground:
f
f on pins 1 to 4 sense +VCC,
f
f on pins 12 to 16 sense –VCC.
3. The unit should start to work at about 90 VAC. The
Rail voltages ±VCC must be about ±40VDC.
FIGURE 14: MOSFETs.
FIGURE 13: Output MOSFETs on the bottom side of the PCB.
9
13 Spare part list
D-Cell 504
Powersoft
code
Description
Position
FU000020
Fuse 3.15A 250VDc (5x20mm) Fast
CF Series
Main switch
VR000006
VARISTOR S20K300
RV800T
LI000015
PTVA 47UH 1.3A H=14mm
D=9.4mm
L835T
FUS00001
FUSE 10A 6.1mmx2.69mm FAST F
serie451 LITTELFUSE
F800T, F801T
MO000043
IRC IRFB5615PBF
150V/25A/32mOhm
Q200, Q201,
Q500, Q501
IS000042
GAP PAD ULTRASOFT 40MILS
18X50 DIGIMOD
Q200, Q201,
Q500, Q501
10
Via Enrico Conti, 5
50018 Scandicci (FI) Italy
Tel: +39 055 735 0230
Fax: +39 055 735 6235
General inquiries: [email protected]
Sales: [email protected]
Application & technical support: [email protected]
Service & maintenance: [email protected]
www.powersoft-audio.com
© 2012 - 2013 Powersoft
powersoft_DCell504_servman_en_v1.2
