HP 3455A - Page 190

Turn The Instrument OFF.
Reconnect The
Plug
To
A1J7. Be
Certain That The
Test
Jumper On The A3
Assembly Is
Disconnected.
Turn The Instrument ON.
The Device Select
^
Signal
Present
At
Pln9O1A10U157
(This Signal Is A
Negatlve*Golng
Pulse
Approximately
1
psec
In
Duration And
>
4 Volts Pealt-To-
\
Peak.)
/
Are
\
The
Signals
At
Pins
2,
10.
And 12
Of A10U1S > 3.5
Volts Peak-To-Peak
\
?
/
Troubleshoot The Device
Select
Circuit (A10U14,
U26
And Associated
Com-
ponents).
Troubleshoot
The
A/0
Switching
Circuit
<A10U15. A14U1.
U2, Q1
Through
Q4 And
Associ-
ated
Components).
__X^The
Voiiage^Ss.^^
At
A14TP1 Greater
•s..,TI«n
+
10 Vdc^
The Voltage
At
Pin 14
Of
The
A14
Assembly
>
+
4
V dc
\
The Voltage At
Pin 15 Of The
A14
[
NO
Assembly
> + 4
Vde I
\ /
The Voltage At
Pins Of The
A14
Assembly
>
4 V dc
s.
7
^
Troubleshoot The
Inte-
grator Circuit
IA14U3.
U4,
05
,
04 And
Associated
Components).
Troubleshoot
The
.2 V
(5e-
1
tect And
Absolute Value
Circuits {A14US, U6, 06
And Associated
Compo-
nents).
Troubleshoot
The
10 V
Detect
And Absolute
Value Circuits (A14U5,
U6. 06
And Associated
Components).
The Voltage At
Pin 15 Of The A14
Assembly
<t
Volts
± .3 V dc?
^
Troubleshoot
The
10
V
Detect
And Absolute
Value
Circuits (A14U5.
U6, 06
And
Associated
Components).
The Voltage At
PinSOf TheA14
Assembly
0
Volts
. ±
.3 V dc?
^
Remove The
from
A14C2.
Troubleshoot The
0
Detect
Circuit
(A14U6
And
Associated
Components).
Troubleshoot
The
0
Detect
Circuit
(A14U6
And
Associated Components).
If.
At
This Point.
The Problem Has Not
Been Isolated To A
Circuit.
Recheck The
Symptonrrs To Be Certain
The Problem
Is
In The Inguard Section
Of The Instru-
ment. Refer
To
The Theory Of
Opera-
tion And Schematics To
Locate Prob-
lems Not
Covered
By
This Procedure.
The
A/0
Input
^
Voltage At A10TP4
\
-lOVdc?
^
Troubleshoot
The
DC
Preamp
And Input Switch-
ing Circuitry (Schematic
No. 1).
Be Certain That
•
10
V dc
Is Applied To
The 34S5A
Input Termi-
nals.
Force The
Integrator To
Auio-Zaro
By
Connecting
A
Clip Lead
Between
The
Cathode
Of A14CR8
And
Inguard Ground.
ReferenceN^.
Voltage
At
A10TP7
\
-lOVdc? /
x'^The Reference's
Voltage At
A10TP8
\
-f
lOVdc?
/
Troubleshoot
The Refer-
ence Supplies (All Assem-
bly, A10U7, A14U1. U2
And Associated Compo-
nents).
The Voltage At 1
A14TP1
0 Vdc
±
.2 Vdcf
\
?
>
Troubleshoot
The Inte-
grator Circuit (A14U3, U4.
4.
05
And Associated
Components).
Figure
8-H-19.
Inguard
Troubleshooting
Procedure
Diagram,
3455
-
0-12
8-115/8-116