Reference Voltages; Buzzer Circuit; Reset Rom Line (Romrst); Ram Test - Fluke 43B Service Manual

43B
Service Manual

7.5.9 Reference Voltages

1. Check:

7.5.10 Buzzer Circuit

1. Press
2. Short circuit Input 1 to COM. The buzzer is activated now.
3. Check TP496 for a 4 kHz, 0...3V square wave during beeping (+3 V if not activated).
4. Check TP495 for a 4 kHz +3...-30V square wave during beeping (TP495 is +3V if

7.5.11 Reset ROM Line (ROMRST)

1. Check TP487 for +3V (supplied by D471).

7.5.12 RAM Test

You can use the Microsoft Windows Terminal program to test the RAM. Proceed as
follows:
1. Connect the Test Tool to a PC via the Optical Interface Cable PM9080.
2. Start the Terminal program, and select the following Settings:
3. Turn the test tool off. Keep the keys
7-14
a. TP306 for +3.3V, TP307 for +1.23V
If not correct check/replace V301, R307, C3112, P-ASIC N501.
b. TP301 for +1.6V ;
TP310, see figure below (in ROLL mode TP310 is zero).
If not correct, check/replace REFERENCE GAIN circuit and T-ASIC N301.
TP310
≈ 800 ms
and select OHMS/CONTINUITY/CAPACITANCE.
Press (Continuity).
the beeper is not activated).
Terminal Emulation
Terminal Preferences
Echo
Communications
This will start up the mask software. You will hear a very weak beep now.
TP302 for +0.1V ;
+1.2V
-1.2V
TTY (Generic)
Terminal Modes
pressed, and turn the test tool on again.
TP304 for +3.3V ;
CR -> CR/LF
Inbound
Outbound
Baud Rate
Data Bits
Stop Bits
Parity
Flow Control
Connector
Line Wrap
Local
Sound
9600
8
1
None
Xon/Xoff
COMn