Tektronix 2215A, Instruction Manual

Page: 89 / 206

Maintenance— 2215A Service
C2662-50
Figure 6-1. Multi-connector holder orientation.
When the defective component is located, replace it, using
the appropriate replacement procedure given under “Cor­
rective Maintenance” in this section.
Before using any test equipment to make measure­
ments on static-sensitive, current-sensitive, o r volt­
age-sensitive components o r assemblies, ensure that
any voltage o r current supplied by the test equipment
does not exceed the lim its o f the component to be
tested.
1. Check Control Settings
Incorrect control settings can give a false indication of
instrument malfunction. If there is any question about the
correct function or operation of any control, refer to either
the "Operating Instructions” (Section 2) in this manual or to
the instrument Operators Manual.
2. Check Associated Equipm ent
Before proceeding, ensure that any equipment used with
this instrument is operating correctly. Verify that input sig­
nals are properly connected and that the interconnecting
cables are not defective. Check the power-input-source
voltages.
W A R M I N G
To avoid electrical shock, disconnect the instrument
from the power-input source before perform ing visual
inspection.
3. Visual Check
Perform a visual inspection. This check may reveal bro­
ken connections or wires, damaged components, semi­
conductors not firmly mounted, damaged circuit boards, or
other clues.
W A R N I N G
Dangerous potentials exist at several points through­
out this instrument. If it is operated with the cabinet
removed, do not touch exposed connections or
components.
4. Check Instrument Perform ance and Adjustment
Check the performance of either those circuits where
trouble appears to exist or the entire instrument. The appar­
ent trouble may only be the result of misadjustment. Com­
plete performance check and adjustment instructions are
given in Sections 4 and 5 of this manual.
5. Isolate Trouble to a Circuit
To isolate problems to a particular area, use the trouble
symptom to help identify the circuit in which the trouble is
located. Refer to the troubleshooting charts in the “Dia­
grams” section as an aid in locating a faulty circuit.
6. Check Power Supplies
W A R N I N G
I
For safety reasons an isolation transformer m ust be
connected whenever troubleshooting is done in the
Preregulator and the Inverter Power Supply sections.
Check the power supplies whenever trouble symptoms
appear in more than one circuit. The correct output voltage
and ripple for each supply should be measured between the
supply test point and chassis ground test point (see Table 6-
4). Voltages may be measured with a DMM, while the ripple
measurements are accomplished with an oscilloscope. Be­
fore checking power-supply circuitry set the A INTENSITY
control to minimum brightness and the A SEC/DIV switch to
X-Y mode.
When measuring ripple, use a 1X probe with a bayonet
signal tip attached to the probe tip to minimize stray pickup.
Insert the bayonet signal tip to the first test point indicated
in Table 6-4 and touch the bayonet ground tip to the chassis
ground near the test point. The ripple values listed in Table
6-7