No Picture - promethean PRM-30A Service Manual

Troubleshooting

No Picture

Check following steps.
No picture with all of in-
put sources
No
No picture with PC1 [An-
alog] input source only
No
No picture with PC2
[Analog] input source
only
No
No picture with all of
computer input sources
No
No picture with video in-
put sources
Yes
Check signal processing stage and LCD driving stage;
C heck RGB S&H signals at test points TP35B, TP35G, TP35R.
C heck power supply circuit 15.5V_PNL and peripheral circuit.
C heck ICs IC501, IC531, IC561, IC401, IC301 and peripheral cir-
cuits.
Yes
C heck IC4001 <Amplifier/Switch> and peripheral circuit.
Yes
Check IC301<Scaler> and peripheral circuit.
Yes
Check PC/AV source selecting stage and processing stage;
C heck IC4701 and IC301<Scaler> and peripheral circuit.
Check AV source selecting and decoding stage;
S-Video source
Check S-video signal (Y/C).
S _CHROMA signal is applied to pin 65 of IC301<Scaler>, and S-Y signal is
applied on pin 64 of IC301.
Composite video source
Check composite video signal (Video).
T he composite video signal is applied to pins 6 of IC301 <Scaler>.
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