Daewoo DWF-5590DP Series, Service Manual

Page: 42 / 63

2) EXPLANATION OF CIRCUIT
• The MICOM terminal No. 33~40 amplifies the source current to produce the 'H' by use of the buffer UDN-2981A. And
the MICOM terminal No. 43~54 sufficiently amplifies the sink current by use of the DRIVE I.C. ULN-2004A.
• The waveform between the part of
!
and the GND (part of the DUTY).
The division rate of the DUTY is 1/9. And as part of the DUTY treats the black time between the square waves, it
prevents the phenomenon of faint lighting of L.E.D unnecessarily due to the phenomenon of fold in delay time of the IC
8 between the input and the output.
• The equivalent circuit of DRIVE IC & BUFFER IC.
• If the light of the DISPLAY unit is does not appear, check the circuit using the oscilloscope.
42
0V
5.4V
t
3.085 mSEC
R7, 2k
INPUT
10.5K
COMMON
OUTPUT
GND
VD
20K
298/84 Only
7.2K
3K
OUTPUT
1.5K
INPUT
GND
UDN-2981N
ULN-2004A