HP 3478A Technical Manual page 92

3478A 3478A
Figure 7-D-7 Figure 7-D-7. . JM403 SA
4. 4. If p If pin 3 in 3 of U of U466
replace U467. replace U467.
c. c. If th If the RES e RESET lin ET line is hig
line, press the 3478A's blue Shift button and then the line, press the 3478A's blue Shift button and then the
SGL/TRIB (TEST/RESET) bu SGL/TRIB (TEST/RESET) button.
through its Self-Test routine, and when the routine is through its Self-Test routine, and when the routine is
finished, the RESET line toggles from high to low to high. finished, the RESET line toggles from high to low
d. d. If th If the RES e RESET lin ET line tog
in- operative, replace U462. in- operative, replace U462.
e. e. If t If the R he RESE ESET lin T line do
following: following:
1. 1. Mak Make su e sure re pin pin 1 of
2. 2. If pi If pin 1 n 1 is no is not to
may may be be at at fault. fault.
troubleshooting. troubleshooting.
3. 3. If pin 1 i If pin 1 is tog s toggli gling, re ng, repla
7-D-44. 7-D -44. ISO ISOLAT LATION CIR ION CIRCUI
7-D-45. The Isolation 7-D-45. The Isolation Circuitry t Circuitry transfers information from
the Main Controller (U501) to the A/D Controller (U462) the Main Controller (U501) to the A/D Controller (U462)
and also from the A/D Controller to the Main Controller. and also from the A/D Controller to the Main Controller.
A failure in the logic is normally indicated when, after A failure in the logic is normally indicated when, after
doing a Self-Test, "A:D doing a Self-Test, "A:D LINK FAI
troubleshoot the circuitry, first determine the inoperative troubleshoot the circuitry, first determine the inoperative
circuitry a circuitry and then nd then troubleshoot troubleshoot the cir-
following: following:
a. a. Tu Turn rn th the 3 e 347 478A 8A of off. f.
b. b. Mo Move j ve jumpe umpers J rs JM50
position. position.
c. c. Con Connec nect th t the Fl e Float
3478A's chassis. 3478A's chassis. The LO INPUT The LO INPUT terminal can
JM403 SA Connection Connection
466 is h is high igh, r , repl eplace ace U46 U466. 6. If l
e is high, wh h, while mo ile monit nitori
tton. The 3478A should The 3478A should go
e toggle gles and th s and the 347 e 3478A is st
e does no es not to t toggl ggle, do e, do the
1 of U46 U467 is 7 is tog toggli gling. ng.
t toggling ggling, th , the Is e Isolati olation Ci on Cir- cu
Go to to paragraph Go paragraph 7-D-44 7-D-44 for
place U4 ce U486 an 86 and the d then U46
CUITRY TR TRY TROU OUBL BLES ESHO HOOT
ransfers information from
LINK FAIL" is L" is displayed. displayed.
the cir- cuitry. cuitry. Do the
M502 an 2 and JM d JM503 503 to t to the "
oating C ing Commo ommon gro n ground und to t
terminal can be be
used as a Floating Common ground (make sure the cor- used as a Floating Common ground (make sure the cor-
rect terminal is used, dependent on the position of the rect terminal is used, dependent on the position of the
Front/Rear Switch). Front/Rear Switch).
d. d. Con
follows: follows:
S S t t a a r r t t : :
S S t t o o p p : :
C C l l o o c c k k : :
H H o o l l d d : :
Self-Test: Out Self-Test: Out
G G n n d d : :
If low, ow,
e. e. Tur
the Chassis Common + 5V power supply. the Chassis Common + 5V power supply.
oring th ng the e
f. f.
SA probe is toggling, the Main Controller (U501) may be SA probe is toggling, the Main Controller (U501) may be
go
defective. defective. Go
paragraph 7-D-II 1). paragraph 7-D-II 1).
to high.
g. g. If th
8A is still ill
be the same or different), the isolation circuitry is defec- be the same or different), the isolation circuitry is defec-
tive. Do tive. Do the
the
U508 are toggling. U508 are toggling.
r- cuitry itry
for
transformer transformer T501 and
good, replace U468. good, replace U468.
n U467. 7.
h. h. If t
U462 are good, the isolation logic used to transfer U462 are good, the isolation logic used to transfer
OTIN ING G information between U462 and U501 may be defective. information between U462 and U501 may be defective.
Do the following: Do the following:
is toggling. is toggling.
To To
tive. tive. Go to Go to Flowchart
Do the
U467 are toggling. U467 are toggling.
he "D" D"
transformer T401 and transformer
to the he good, replace U550. good, replace U550.
7-D-10 7-D-10
Connec nect and s t and set th et the Sig e Signat
U U 4 4 6 6 2 2 p p i i n n 1 1 ( ( ) )
T T P P 8 8 ( ( ) )
T T P P 3 3 ( ( ) )
O O u u t t
C C h h a a s s s s i i s s G G r r o o u u n n d d
Turn the n the 347 3478A on 8A on and c and chec
If the s If t he sign ignatu ature i re is dif s differ ferent
Go to to Flowchart Flowchart A A for
If the SA p e SA probe robe is not is not togg toggling (
the following: following:
1.Using a logic probe, make sure pins 2 and 4 of 1.Using a logic probe, make sure pins 2 and 4 of
2.If the pins 2.If the pins are not toggling, replace U508. are not toggling, replace U508.
3.If they are toggling, check for a defective 3.If they are toggling, check for a defective
T501 and associated circuit associated circuitry.
If the si he signa gnals at ls at pin 3 pin 38 of U 8 of U501 a
1.Using a logic probe, make sure pin 38 of U462 1.Using a logic probe, make sure pin 38 of U462
2.If pin 38 is not toggling, U462 may be defec- 2.If pin 38 is not toggling, U462 may be defec-
Flowchart D for D for troubleshooting. troubleshooting.
3.If pin 38 is toggling, make sure pin 1 and 4 of 3.If pin 38 is toggling, make sure pin 1 and 4 of
4.If the pins 4.If the pins are not toggling, replace U467. are not toggling, replace U467.
5.If they are toggling, check for a defective 5.If they are toggling, check for a defective
T401 and associated circuit associated circuitry.
TM 11-6625-3071-14 TM 11-6625-3071-14
nature A ure Anal nalyz yzer as er as
heck the si k the signa gnatur ture of e of
ent tha than "HF n "HF52" a 52" and t nd the he
for troubleshooting troubleshooting (see (see
ling (the s the signat ignature ca ure can n
ry. If T501 If T501 is is
501 and p nd pin 14 o in 14 of f
ry. If T401 If T401 is is