36
9. DAV-C700 Switching Type Power Supply
3. Plug the unit into AC and press the front panel Power ON switch so it latches in. The power supply should
start and produce the following voltage. See Chart 9-7 below:
Chart 9-7 - No Load Power Supply Output Voltages – Use Cold Ground
Location
No Load Voltage
Normal Power ON Voltage
CN904/pin 1, 2
27-29Vdc
27Vdc
CN905/pin 1
14.3Vdc
13.6Vdc
CN905/pin 2
6.8Vdc
6.4Vdc
CN905/pin 3
0V *
3.3Vdc
CN905/pin 4
5.6Vdc
5.6Vdc
* 3V will output if a HIGH is also placed at CN905/pins 10 & 11.
VI - Troubleshooting Shortcuts
Because the circuit board is dense, access to some parts is difficult or impossible from the top of the board.
Temporally changing circuit conditions to see if some circuit groups work in this power supply is a good way to
speedily arrive at the non-working part. These shortcuts do not replace a complete troubleshooting plan.
Chart 9-8 - Shortcut Procedures
Purpose
Conditions
Procedure
Normal Result
Parts Tested
See if CPU pwr ON
command arrives at
PC902
Standby Mode (front
panel button in)
Press the Play
or an Eject
button to power
ON.
Voltage at
PC902/pin 2
should change
from 4.7V to
5.6V
Stby voltage,
IC907, Q915, Pwr
ON Path from
CPU (DVD bd.).
See if CPU pwr ON
command finally
arrives at IC901/pin
4.
Standby Mode – Release
front panel Pwr to turn
OFF unit, then press
button in again.
Short
PC902/pins 1
and 2 together.
Voltage at
IC901/pin 4
should change
from 11V to 20V.
Q901-Q903,
D903, PC902
See if CPU pwr ON
command also
enables the
regulating circuit
(cancels the Stby
Mode).
Standby Mode – Release
front panel Pwr to turn
OFF unit, then press
button in again.
Press the Play
or an Eject
button to power
ON.
Voltage at
D912/Cathode
(band) should
change from
14.8V to 28V
D917, Q905,
Q908.
PS. Shorting pins of PC901 (regulating circuit) will cause IC901’s oscillator to stop until power is removed (no
damage will result). The power supply’s 27V output line will momentarily rise from 19V to 38Vdc when pins 1-
2 are shorted, or decay toward 0 when pins 3-4 are shorted.
Caution: Never cause the power supply output to go to a maximum of 38Vdc while connected to the load.
Summary of Contents for STR-DE845
Page 59: ...APPENDIX ...