Service manual

Troubleshooting Tables
4-8
Remember that most noise results from poor patient-electrode connections or poor quality
electrodes. If noise persists after checking electrode placement and lead-electrode
connections, the noise may be due to poor quality electrodes. Some electrodes have a shelf
life of 48 hours or less once the foil package is opened. Eliminate electrode placement,
connections, and freshness as the causes of the noise before replacing the patient cable.
Bad ECG:
Good calibration pulse in
channels where traces are not
good.
A lead is missing — dotted
line on trace.
Noisy lead(s): “AC” (regular
pattern) — for 60 Hz, 12
peaks/5 mm at 25 mm/sec;
for 50 Hz, 10 peaks/5 mm.
Faulty operator technique; poor electrode
contact
Defective leadwires.
Defective ECG front end.
Faulty operator technique; poor electrode
contact.
Defective leadwires.
Defective ECG front end.
Faulty operator technique; poor electrode
contact.
Patient or patient cable near AC power.
Lead wires may be picking up interference
from poorly grounded equipment near the
patient.
Patient cable is too close to the cardiograph
or other power cords.
Refer to Table 6-2 in user’s manual.
Replace patient cable.
Replace CPU assembly.
Refer to Table 6-2 in user’s manual.
Replace patient cable.
Replace CPU assembly.
Refer to Table 6-2 in user guide.
Reposition patient cable. Refer to Table 6-2 in
user guide.Try unplugging cardiograph from the
AC outlet.
Route lead wires along limbs and away from
other electrical equipment. Fix or move poorly
grounded equipment.
Move the cardiograph away from the patient.
Unplug the cardiograph and operate on battery.
Unplug the electric bed.
Noisy leads: Muscle artifact. Patient is not relaxed or skin has been irri-
tated.
Low quality disposable electrodes, leadwire
adapters.
Refer to Table 6-2 in User Guide.
Replace disposable electrodes or leadwire adapt-
ers.
Test with ECG simulator. Replace patient cable.
Noisy lead(s): I, III, aVL LA leadwire defective. Replace patient cable.
Noisy lead(s): II, III, aVF LL leadwire defective. Replace patient cable.
Noisy lead(s): I, II, aVR RA leadwire defective. Replace patient cable.
Noise in only one V lead. Faulty operator technique; poor electrode
contact.
Defective leadwires
Refer to Table 6-2 in user guide.
Replace patient cable.
Noise in general. Faulty operator technique; poor electrode
contact.
Defective leadwires.
Refer to Table 6-2 in user guide.
Replace patient cable.
Table 4-3 Patient Cable and ECG Front End
Symptom Possible Cause Corrective Action
NOTE