Service manual

Checking the Power Supply
CHECKING THE POWER SUPPLY
Some ASR-10 problems may be related to a faulty power supply, transformer or line filter. You should
check these before troubleshooting the rest of the unit. Measure continuity across all the fuses to
make sure they are not blown.
Make sure that all the cable connections are secure and correct. Plug the ASR-10 in and turn it on.
After it has warmed up for five minutes, begin to test the voltages at the points shown in Figures 8 and 9.
It is normal for Line Voltage to vary +/- 10%. If the voltages vary outside the allowable limits, follow
the procedure described under TESTING THE POWER SUPPLY UNLOADED (pp. 14-15) before
replacing it.
The voltage and part number of the chassis mount transformer are on the label on the top of the
transformer. The power supply part number is silk-screened near the center of the power supply PC
board. The chassis mount transformer part numbers for the ASR-10 are:
1OOV 1450000722 230V 1450000352
12OV 1450000342 240V 1450000932
These lugs are on the
power supply board.
v
green wire
Tground to
Filter 1
Power Switch
I
Rear of ASR-10 Keyboard Unit
case)
NOTE: Wiring
is the same for
the ASR-10 Rack
TR=top right lug
BR=bottom right lug
TL=top left lug
BL=bottom left lug
Analog Board Regulator Voltages
There are seven regulators (VRl through VR7) attached to the analog board heat sink. On the keyboard
version, you can easily check to make sure that they are generatin,
(J the correct voltages. The correct
voltages are silkscreened onto the analog board next to the regulator name. Place your ground (-) probe
on the tab of VR5. To measure the output, place the other probe on pin 3 of the regulator (when the
regulator legs are closest to you, pin 3 is the right leg). It is normal for the voltage to vary f 5%.
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ASR Service Manual