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Service
8-21. Corroded spots are best removed with soap
and water. Stubborn residue can be removed with a
fme abrasive. When using abrasives be careful
that
fine particles do not fall into the instrument. The
cleaned spots can be protected from further cor-
rosion by an application of a silicone resin such as
GE DRIFILM 88.
8-22.
ETCHED CI RCUIT BOARDS.
8-23. The following paragraphs provide servicing
procedures for etched circuit boards.
8-24.
BOARD CONNECTIONS.
8-25. Single-pin connectors on circuit boards are
identified by the color code of the connecting wire.
Connector pins on plugs and jacks are identified by
a numeral or a letter. The letters G, I, 0, and Q are
not used. Table 8-1 shows the type of board con-
nections used in the instrument.
8-26. SWITCH MAINTENANCE.
8-27. The slide switches used on the etched circuit
boards have been designed for long, trouble-free
service. Should one of these switches become defec-
tive, replacement rather than repair is recommended.
8-28. HEAT SINKS.
8-29. The heat sinks used on the instrument are all
of the friction type. They can be removed
by
careful-
ly pulling them off. When reinstalling, support the
bottom of the transistor while pushing the heat sink
on. Transistor damage may result if the transistor
leads are bent.
8-30. SERVICING ETCHED CIRCUIT BOARDS.
8-31. The etched circuit boards in the instrument
have plated-through component holes. This permits
components to be removed by unsoldering from
either side of the board. When removing
large
com-
ponents, such as potentiometers, rotate the soldering
iron tip from lead to lead while applying pressure
to lift the part from the board. HP Service Note
M-20E contains additional information on repair of
etched circuit boards.
8-32. SEMICONDUCTOR REPLACEMENT.
8-33. Figure 8-1 is included to help identify the
leads of common sizes and shapes of semiconductor
devices. When removing a semiconductor, use long-
nosed pliers as a heat sink between the device and
the soldering iron. When installing a semiconductor,
ensure sufficient lead length to dissipate the solder-
ing heat by using the same length of exposed lead
as used for the original part.
8-2
Model 1317A
3-34. TROUBLESHOOTING.
8-35. The most important prerequisite for successful
troubleshooting is understanding how the instrument
is designed to operate and correct use of front-panel
controls. Suspected malfunctions may be caused by
improper control settings or circuit connections.
Before doing the test and/or troubleshooting proce-
dures, read Section III
(Operation)
for an explanation
of controls and connectors and general operating con-
siderations, and Section IV (Principles of Operation)
for an explanation of circuit theory.
8-36. If trouble is suspected, visually inspect the in-
strument. Look for loose or burned components that
might suggest a source of trouble. Check to see that
all circuit board connections are making good con-
tact. If no obvious trouble is found, check the power
supply voltages in the unit. Prior to any extensive
troubleshooting, check the external power sources
also.
8-37. TROUBLESHOOTING THE LOW VOLTAGE
POWER SUPPLY.
8-38. If
the
supply
is
completely inoperative, inspect
the line fuse located on the rear of the instrument.
If
the line fuse is open, the power lamps will not be
lighted.
Check input voltage source for proper voltage.
8-39. The voltage from each secondary winding of
input transformer T1 is rectified by a full-wave
bridge rectifier and filtered by a capacitor (the +250V
supply is filtered by two capacitors). In the event of
diode failure, the supply voltage will vary consider-
ably from the design value and filtering will be
severely affected. Loss of a filter capacitor will affect
the
voltage and result in excess ripple at the series
regulator input.
8-40. Fuses and adjustments for the dc voltages
are located on the low voltage power supply board,
All. The fuses are connected in series with the reg-
ulator transistors.
In
case a fuse is open, check the
series regulator and driver transistors.
8-41. No Output Voltage. No output voltage may
be the result of 'an open fuse, open series regulator
transistor, or loss of the +250V reference voltage.
When all supplies are inoperative, check the +250V
power supply first. Output from this supply 'is re-
quired for the +15V supply. Output from the +15V
supply is required for the -15V supply.
8-42. Voltage Too High. Too high a voltage may be
caused by a shorted series regulator transistor, short-
ed driver transistor, +250V reference voltage out of
regulation, or a defective sensor amplifier. If the ±15V
supplies are low, check the output of the +250V sup-
ply.
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Table of Contents
Troubleshooting
