Tektronix DSA8300, Service Manual

Page: 103 / 138

Troubleshooting
Checking the Power Supply Voltages
You will need a digital voltmeter to check power supply voltages.
1. Power off the mainframe and remove any modules installed in it.
2. Power on the instrument.
3. Connect the reference lead of a digital voltmeter to chassis ground, such as
the top of the power supply.
4. Attach a 0.025 inch square pin to the probe tip of the other lead and insert it
into a pin on one of the connectors. The voltages at the pins are labeled on the
back of the Power Side board, and are listed in the following table:
Power supply voltages
Power Side board connector
Voltage (labeled on back of board)
via Ground
via + 12 VD
via + 5 VD
via + 3.3 VD
via + 5 SB
via On/STBY
P2 (A24, B24, C24) +5 VA
P2 (A17, B17, C17) -5 VA
P2 (A15, B15, C15) +15 VA
P2 (A13, B13, C13) -15 VA
5. Measure the power supply voltages with the voltmeter and compare each
reading to the values listed in the table. If the voltages are within about 5% of
the nominal voltages, your power supply is functional. For more information
about the power supply, refer to the description of the low voltage power
supply. (See page 2-4.)
If the Instrument Will Not
Boot
If there is a display on the DVI-I port, but not on the LCD, replace the display
assembly (LCD, lamps, and cable).
If there is no display, make sure that the display is turned on. At boot time and
while using an external monitor connected to the ATX external video port, press
F2 to enter the BIOS setup. Select the Chipset menu, and then the North Bridge
Con
fi guration menu. Select Video Function Con fi guration and verify that the
Boot Display Device is set to [CRT+LVDS].
If the display is con fi gured correctly in the BIOS, and there is still no display,
the Display Adapter board may be bad.
DSA8300 Digital Serial Analyzer and Modules Service Manual 4–55