Starting With A Dead Test Tool; Test Tool Completely Dead - Fluke ScopeMeter 123 Service Manual

123
Service Manual

7.4 Starting with a Dead Test Tool

If the test tool cannot be turned on, when powered by a charged battery pack, or by the
power adapter, follow the steps below to locate the fault.
1. Connect a power adapter and a charged battery pack.
2. Turn the test tool on and listen if you hear a beep.

7.4.1 Test Tool Completely Dead

1. Turn the test tool off. Keep the keys
2. Check the Keyboard ROW1 line (MS433 next to X452) for a 100 kHz square wave.
3. Check N501 pin 60 (VBATSUP) for >4.8V. If not correct check R503, and
4. Check TP571 (+3V3GAR) for +3V3V.
7-6
The CHARCURR voltage on TP531 is controlled by a pulse width modulated
voltage (CHARCUR) from the D-ASIC D471 (pin 40). The D-ASIC measures the
required signals needed for control, via the Slow ADC.
1. Check the SLOW ADC, see Section 7.5.3.
2. Check VGARVAL (N501 pin 64), for +3.3V. If not correct, check if the line
is shorted to ground. If it is not, then replace N501.
3. Trace the CHARCURR signal path to R534, R 442 and D471 (D-ASIC)
output pin 40.
d. Check the following:
1. C506 and connections to N501.
2. Connections between V506 and N501 pin 16 (CHAGATE).
3. The voltage at TP501 (N501 pin 19, VCHDRIVE) for ≅ 15...20V.
4. The voltage at N501 pin 43 for a triangle waveform, 80...100 kHz, +1.6V to
+3.2V.
5. If 1 to 4 correct, then replace N501.
a. If you hear no beep, continue at 7.4.1 Test Tool Completely Dead.
b. If you hear a weak beep, continue at 7.4.2 Test Tool Software Does not Run.
c. If you hear a "normal" beep, the software runs, but obviously the test tool is not
operative. Continue at 7.4.3 Software Runs, Test Tool not Operative.
This will start up the mask software.
If you still hear no beep, continue at step 2.
If you hear a weak beep now, continue at Section 7.4.2.
If not correct, continue at step 3.
If correct, the mask software runs, but the buzzer circuit does not function. Check
the buzzer function (Section 7.5.10), and then continue at Section 7.4.2.
connections to battery pack.
If not correct, this is possibly caused by V569, R580, TP571 short to ground, loose
pressed, and turn the test tool on again.