Dräger Evita 4 - Testing DC;AC Converter for Backlighting; Tests Possible in DS Mode; Diagnosis Mode; External DS Mode Using PC

5664.500/800 Evita 4/Evita 2 dura 06/98 Repair Instructions Page 63
For internal use only. Copyright reserved. GBR5664500T055664800.fm 18.03.99
Dräger Medizintechnik
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11.4 Testing DC/AC converter for backlighting
The DC/AC converter is to be checked if the entire backlighting fails (=screen blank) and the
display responds to servic ecommands refer to section of "Repair Instructions - Service No./
Modi, Error list" chapter 9.5.6, Testing of display, page 157.
This converter supplies the lamp (NEC display) or the two lamps (Toshiba or Sharp display)
with an AC voltage of approx. 400 V and 50 kHz.
When measuring the voltage with a voltmeter, the voltmeter represents a short circuit for the
converter and the voltage collapses.
The following test is easy to implement: Use a screwdriver to create a spark gap at the lamp
connections.
11.5 Tests possible in DS mode
11.5.1 Diagnosis mode
refer to section of "Repair Instructions - Service No./ Modi, Error list" chapter 3.2.1,
Diagnosis page “Microprocessor” of “Front”, page 64.
This is only possible if display and backlighting are functioning; if not, refer to section of
"Repair Instructions - Service No./ Modi, Error list" chapter 9.5.6, Testing of display, page
157.
11.5.2 External DS mode using PC
refer to section of "Repair Instructions - Service No./ Modi, Error list" chapter 9.5.6, Testing
of display, page 157.
CAUTION
Touching the output contacts of the DC/AC converter results in minor burns
(HF surgery) and can prove extremely unpleasant.