Service manual

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Digital Control Troubleshooting
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6. Digital Control Troubleshooting
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1. Check the Power-On Sequence
See the INSPECT THE POWER-ON SEQUENCE section in chapter 4 for checking the
Power-On Sequence.
Check the [A] and [B] Operations
1. Press [A] and [B] alternately.
2. Check that the two LEDs alternately light each time you press the keys.
• If both LEDs do not light, continue with Check the A1 Eight LEDs.
• If the two LEDs do not alternately light (the [A] LED is still lit even if pressing the
[B]), the A1 CPU is probably faulty. Replace the A1 CPU.
• If the two LEDs alternately light each time you press the keys, the A1 CPU is
probably working properly. Continue with the TROUBLESHOOT THE A51 GSP
AND A52 LCD section in this chapter.
Check the A1 Eight LEDs
The A1 eight LEDs should be in the pattern shown in Figure 6-5 at the end of the power on
sequence. Perform the following procedure to check the A1 eight LEDs.
1. Turn the analyzer turn off.
2. Remove the bottom cover of the analyzer.
3. Turn the analyzer power on.
4. Look at the A1 eight LEDs. Some of the LEDs light during the power on sequence. At
the end of the power on sequence, the LEDs should stay in the pattern shown in
Figure
6-5. If the LEDs stay in another pattern, the A1 CPU is probably faulty. Replace the A1
CPU.