SyncMaster 800TFT 5-1
5 Troubleshooting
Notes: 1. Before troubleshooting, set up the PC’s display as below.
• Resolution: 1280 x 1024
• H-frequency: 64 kHz
• V-frequency: 60 Hz
2. If no picture appears, confirm the power cord is correctly connected.
3. Check the following circuits.
• No raster appears: Stand PCB, Main PCB
• 12V develop but no screen: Main PCB
• 12V does not develop: Main PCB
4. If you push and hold the EXIT button for more than 5 seconds, the monitor automatically reverts back
to the factory preset
5-1 No Power
Does proper DC 12 V appear at
DC jack connected to CN101?
Check Power Adaptor.
Yes
No
Does proper DC 5 V appear at
Pin 4 of IC101?
Check IC101 and related circuit.
Check Q103, Q105 and Q106.
Yes
No
Does proper 5 V - signal appear at
Pin 42 of IC501 (SW_REG_EN)?
Check IC501 and related circuit.
(CN102, Function Key)
Yes
No
5 Troubleshooting
5-2 SyncMaster 800TFT
5-2 No Video
Check signal cable and connection.
Check TFT-LCD panel and Inverter.
Check IC201 and related circuit.
Does the outpus signal appear at RA403 and
R411 of IC406? (LDTGB, LVSYNCB, LHSYNCB,
LCKBB)
Is the output of Pins 1, 17 of IC501 High ?
Yes
No
Yes
No
Does the analog video signal appear at R211,
R212, R215? (BLUE, GREEN, RED)
(IC201)
Yes
Check IC201, IC206 and related
circuit.
Does the sync signal appear
at the output of Pin 14 of IC201and Pin 3 of IC 206 ?
(V-SYNC, H*V SYNC)
Yes
No
Check the related circuit for these
ports.
No
Check IC501 and related circuit.
No
Check IC501 and related circuit.
No
Check IC 300 and related circuit.
No
Does the input signal appear at the Pins 40, 41
of IC 300?
(PLL H*V MX-PDEN)
Yes
During power on-off does the input signal
appear at the Pin 29,30 of IC300?
(AD-SDA, AD-SCL)
Do the clock and sync signal appear at Pin
115, 117 of IC 300?
(DCLKAB, MX_HSYNC) and does the digital video
signal appear at thr output port PDA, PDB)?
Yes
During power on-off dose the input signal
appear at the R 407 and R 408 ?
(MX-SDA, MX-SCL)
Yes
7 8
9 10
Check IC 406 and related circuit.
Yes
1 2 3 4
5 6
No
Check IC501 and related circuit
5 Troubleshooting
SyncMaster 800TFT 5-3
WAVEFORMS
4
CH1 RMS = 2.20V
5
CH1 RMS = 4.96V
6
CH1 RMS = 4.42V
8
CH1 RMS = 3.24V
9
CH1 RMS = 2.50V
2
CH1 RMS = 3.25V
3
CH1 RMS = 3.12V
7
CH1 RMS = 3.20V
10
CH1 RMS =960mV
1
CH1 RMS = 3.26V
5 Troubleshooting
5-4 SyncMaster 800TFT
Replace IC404.
Yes
No
There is video but no OSD.
5-3 No OSD
While pushing a front control
button does any pulse appear
at Pin 12 of IC404?
WAVEFORMS
Does input signal appear
at the Pins 2, 5 and
10 of IC404?
Check IC405 and related circuit.
Check IC404 and related circuit.
Yes
No
11 12 13
11
CH1 RMS = 4.18V
13
CH1 RMS = 3.26V
12
CH1 RMS = 3.26V
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