Hi, I rescued a Samsung UN40H5003AF (H = 2014 FHD) from the curb. Symptoms are: standby (red) light comes on, stays on for 8 seconds, flickers off, then comes back on, and the cycle continues.
Service manual: https://www.electronica-pt.com/esque...is-u8la-71272/
SMPS board: checked voltages, all seem normal (A13V = 12.8V, UD = 3.3V, PWM_BLU = 0.77V, PS_OnOff = 5.5V). Remove 10p cable to main board -> backlight comes on. I think this means SMPS board and backlight are good.
Main board: BN94-07592P / BN97-08922R / BN41-02263 - see attached photo.
Multiple power supplies:
RAM: I don't see any on the board. Service manuals refers to "Check B1.8V of DDR IC" but I don't see any DDR IC. Back of board is empty.
SPI flash IC601_4MB: Winbond 4 MB, can be read with a SOIC8 clip, strings like "BD_SECXL1_D01B_S", "MSIF0000S3", "MBOT020600622871000", "T-MXL1AUSC-1005.0", "Hello Eden standby mode", "Enter EDEN PM Standby". Boot loader source code: https://github.com/neuschaefer/mstar-mboot
CN801_DB debug UART 3.3V shows this output on every boot cycle:
According to another post (https://www.badcaps.net/forum/troubl...08#post1274408), it should print more messages (SBOOT:AC ON, Hello Eden standby mode, ...).
Service manual "4-2. How to Check Fault Symptom" says "Check the Q206 base, voltage must be no larger than 0.5V". Mine is 0.57V. Is this a significant difference?
Q206 collector does have pulses at the same time as the standby LED, so it seems involved in the power-up circuit. But I don't have schematic so I can't really understand the meaning. And my meter is a little too slow to capture them reliably. I think most rails are steady (no pulses).
I have done some dumb basic checks like:
- Check all capacitors for shorts, all look good.
- Check all SMD fuses / chokes, all show continuity.
Found some schematics here with similar main board part number (https://www.eserviceinfo.com/downloa...ain%20sch.html) but it's not exactly the same power rails, the schematics has DDR while mine doesn't, etc.
Any idea what I could try next?
Service manual: https://www.electronica-pt.com/esque...is-u8la-71272/
SMPS board: checked voltages, all seem normal (A13V = 12.8V, UD = 3.3V, PWM_BLU = 0.77V, PS_OnOff = 5.5V). Remove 10p cable to main board -> backlight comes on. I think this means SMPS board and backlight are good.
Main board: BN94-07592P / BN97-08922R / BN41-02263 - see attached photo.
Multiple power supplies:
- IC203 SMPS AOZ3015PI input 12.8V output 4.94V
- IC204 LDO input 5.0V output 1.8V
- IC205 LDO input 5.0V output 3.3V
- IC201 LDO input 5.0V output 3.3V
- IC501 LDO input 5.0V output 3.3V
- IC206 SMPS input 12.8V output 1.17V
RAM: I don't see any on the board. Service manuals refers to "Check B1.8V of DDR IC" but I don't see any DDR IC. Back of board is empty.
SPI flash IC601_4MB: Winbond 4 MB, can be read with a SOIC8 clip, strings like "BD_SECXL1_D01B_S", "MSIF0000S3", "MBOT020600622871000", "T-MXL1AUSC-1005.0", "Hello Eden standby mode", "Enter EDEN PM Standby". Boot loader source code: https://github.com/neuschaefer/mstar-mboot
CN801_DB debug UART 3.3V shows this output on every boot cycle:
Code:
Eden: BD_SECXL1_D01B_S SPI BOOT Console Initial OK 65 [123456789][123456789] 0055 BIST_0 PASS. MIU Initial OK 0328
Service manual "4-2. How to Check Fault Symptom" says "Check the Q206 base, voltage must be no larger than 0.5V". Mine is 0.57V. Is this a significant difference?
Q206 collector does have pulses at the same time as the standby LED, so it seems involved in the power-up circuit. But I don't have schematic so I can't really understand the meaning. And my meter is a little too slow to capture them reliably. I think most rails are steady (no pulses).
I have done some dumb basic checks like:
- Check all capacitors for shorts, all look good.
- Check all SMD fuses / chokes, all show continuity.
Found some schematics here with similar main board part number (https://www.eserviceinfo.com/downloa...ain%20sch.html) but it's not exactly the same power rails, the schematics has DDR while mine doesn't, etc.
Any idea what I could try next?
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