Troubleshooting 41
Note
Because test points on the FET board are not accessible when the board is installed, troubleshooting must
be performed with the board removed from the power supply (refer to the disassembly procedures at the
back of this chapter
If any power FET (Q201-204, Q301-304, Q211, Q311, Q222, Q322, Q233, Q333, Q244, Q344) is
defective, you must replace all eight with a matched set.
TURN OFF SUPPLY AND REMOVE
A3 FET BOARD WITH HEATSINK
MEASURE RESISTANCE BETWEEN
+RAIL AND -RAIL (E201 AND E301)
>=20 Mohm?
>15 Kohms?
CONTINUE WITH DYNAMIC
YES
YES
YES
NO
NO
NO
(SEE DISASSEMBLY PROCEDURES)
PROBABLE DEFECTIVE
A3 BOARD
MEASURE RESISTANCE BETWEEN
THE GATE OF EACH FET AND
COMMON (-RAIL)
MEASURE RESISTANCE ACROSS
CAPACITOR C201 AND C301.
approx.
150 ohms?
YES
NO
MEASURE RESISTANCE ACROSS
15V BIAS INPUT.
1k ohm forward?
490 ohm reverse?
TROUBLESHOOTING IN TABLE 6-3.
NOTE:
BECAUSE TEST POINTS ON THE A3 FET BOARD ARE NOT
ACCESSIBLE WHEN THE BOARD IS INSTALLED, TROUBLESHOOTING
MUST BE PERFORMED WITH THE BOARD REMOVED FROM THE SUPPLY.
ASSEMBLY ATTACHED.
PROBABLE DEFECTIVE
A3 BOARD
PROBABLE DEFECTIVE
A3 BOARD
PROBABLE DEFECTIVE
A3 BOARD
(E206 TO E207 AND E306 TO E307)
Figure 3-11. FET Troubleshooting Chart)
Summary of Contents for 669 A Series
Page 2: ...Service Manual Keysight Series 669xA GPIB DC Power Supplies ...
Page 3: ......
Page 27: ......
Page 56: ...Troubleshooting 53 Figure 3 15 3 Inch Front Panel Frame Assembly ...
Page 57: ...54 Troubleshooting Figure 3 16 Assembly A10 Exploded View ...
Page 58: ...Troubleshooting 55 Figure 3 17 Assembly A10 Exploded View 6690A ...
Page 59: ...56 Troubleshooting Figure 3 18 Assembly A10 Exploded View 6691A 6692A ...
Page 60: ...Troubleshooting 57 Figure 3 19 Three Phase Line Choke Subchassis Wiring ...
Page 61: ...58 Troubleshooting Figure 3 20 24 Volt Fan Transformer ...
Page 77: ...74 Diagrams Figure 6 1 Test Point Waveforms for Table 6 3 sheet 2 of 2 ...
Page 79: ...Figure 6 3 A1 Front Panel Board Assembly Diagram ...
Page 81: ...Figure 6 5 A2 GPIB Board Component Location ...
Page 83: ...Figure 6 7 A3 FET Board Component and Test Point Location ...
Page 87: ...Figure 6 11 A4 AC Input Board Component and Test Point Location 12 9 10 11 ...
Page 89: ...Figure 6 13 A5 DC Rail Board Component and Test Point Location 13 14 ...
Page 91: ...Figure 6 15 A6 Bias Board Component and Test Point Location 15 16 17 18 19 19 20 22 ...
Page 94: ...Figure 6 17 Power Mesh Schematic Diagram All Models ...
Page 103: ......