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T420s FHD Mod and BOE NV140FHM-N41 Panel

T400/410/420 and T500/510/520 series specific matters only
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jal2
Posts: 15
Joined: Mon Mar 21, 2011 9:56 am
Location: Berlin, Germany

T420s FHD Mod and BOE NV140FHM-N41 Panel

#1 Post by jal2 » Sun Feb 18, 2018 3:42 pm

Hi,

I've got one of the infamous BOE NV140-FHM N-41 panels from an ebay shop, which doesn't work with the FHD Mod PCB, but run fine in the T440 / T450.
As I have both T420s and T440p at hand, I tried to figure out why and had a look at the EDIDs of the NV140 and the FHD Mod PCB (which probably is the EDID of a AUO B140HAN01.x) using the tools get-edid and parse-edid from the read-edid package under Xubuntu 17.10:
NV140FHM-N41 EDID wrote: Section "Monitor"
...
DisplaySize 310 170
Gamma 2.20
Option "DPMS" "false"
Modeline "Mode 0" 147.80 1920 1968 2000 2200 1080 1083 1088 1120 +hsync -vsync
EndSection
FHD Mod (PCB Rev. A1.04, FW Rev. <red>) EDID wrote: Section "Monitor"
...
DisplaySize 310 170
Gamma 2.20
Option "DPMS" "true"
Modeline "Mode 0" 138.65 1920 1968 2000 2080 1080 1083 1088 1111 +hsync +vsync
EndSection
If you look at the "Modeline" lines, you see that both screens differ in dot clock, timings and the polarity of vsync. I'm not sure about dotclock and timings, but the difference in vsync polarity will
surely prevent us from using the NV140FHM with the FHD Mod.

I wonder if changing the EEPROM on the FHD Mod would help here. The vsync polarity is a register value of the LVDS-eDP converter chip and its registers are probably programmed during startup. I have no idea if these values are fixed or taken from the EDID of the attached screen, read from the AUX channel. In the latter case an update of the EEPROM chip would be enough.

BTW, I don't recommend the NV140FHM as a panel, as the specifications of the AUO B140HAN01.x or the Chimei N140HCE-EN1 look better.

Cheers,
Joerg

pathan421id
Posts: 24
Joined: Mon Jan 22, 2018 6:36 pm
Location: Ontario, CA

Re: T420s FHD Mod and BOE NV140FHM-N41 Panel

#2 Post by pathan421id » Mon Feb 19, 2018 1:43 am

The BOE panel is only 6-bit compared to the B140HAN01.0 6+2FRC?

jal2
Posts: 15
Joined: Mon Mar 21, 2011 9:56 am
Location: Berlin, Germany

Re: T420s FHD Mod and BOE NV140FHM-N41 Panel

#3 Post by jal2 » Mon Feb 19, 2018 4:12 pm

I've found this specification on the web, too. But if I look into the EDID, also the one of the FHD mod (copied from B140HAN01.2 I guess) says "6 bits per primary color channel". Are the FRC bits transmitted in some separate eDP packets?
Main question is, if a simple update of the FHD mod PCB EDID would be enough to get the NV140FHM-N41 working with the FHD mod.

Here are the EDIDs again, decoded with edid-decode:
NV140FHM-N41 EDID wrote: Extracted contents:
header: 00 ff ff ff ff ff ff 00
serial number: 09 e5 37 06 00 00 00 00 03 18
version: 01 04
basic params: 95 1f 11 78 02
chroma info: 9d 40 9a 5d 55 8d 28 1e 50 54
established: 00 00 00
standard: 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01
descriptor 1: bc 39 80 18 71 38 28 40 30 20 35 00 35 ad 10 00 00 1a
descriptor 2: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1a
descriptor 3: 00 00 00 fe 00 42 4f 45 20 44 54 0a 20 20 20 20 20 20
descriptor 4: 00 00 00 fe 00 4e 56 31 34 30 46 48 4d 2d 4e 34 31 0a
extensions: 00
checksum: 31

Manufacturer: BOE Model 637 Serial Number 0
Made week 3 of 2014
EDID version: 1.4
Digital display
6 bits per primary color channel
DisplayPort interface
Maximum image size: 31 cm x 17 cm
Gamma: 2.20
Supported color formats: RGB 4:4:4
First detailed timing is preferred timing
Established timings supported:
Standard timings supported:
Detailed mode: Clock 147.800 MHz, 309 mm x 173 mm
1920 1968 2000 2200 hborder 0
1080 1083 1088 1120 vborder 0
+hsync -vsync
Manufacturer-specified data, tag 0
ASCII string: BOE DT
ASCII string: NV140FHM-N41
Checksum: 0x31

Unknown extension block

EDID block does NOT conform to EDID 1.3!
Missing name descriptor
Missing monitor ranges
FHD mod EDID wrote: Extracted contents:
header: 00 ff ff ff ff ff ff 00
serial number: 30 ae a3 40 00 00 00 00 0c 19
version: 01 04
basic params: 95 1f 11 78 ea
chroma info: 85 45 a4 5a 54 a1 27 0c 50 54
established: 00 00 00
standard: 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01
descriptor 1: 29 36 80 a0 70 38 1f 40 30 20 35 00 35 af 10 00 00 1e
descriptor 2: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
descriptor 3: 00 00 00 0f 00 d1 09 3b d1 09 3b 1e 0a 00 06 af 3d 12
descriptor 4: 00 00 00 fe 00 42 31 34 30 48 41 4e 30 31 2e 32 20 0a
extensions: 00
checksum: 37

Manufacturer: LEN Model 40a3 Serial Number 0
Made week 12 of 2015
EDID version: 1.4
Digital display
6 bits per primary color channel
DisplayPort interface
Maximum image size: 31 cm x 17 cm
Gamma: 2.20
DPMS levels: Standby Suspend Off
Supported color formats: RGB 4:4:4, YCrCb 4:2:2
First detailed timing is preferred timing
Established timings supported:
Standard timings supported:
Detailed mode: Clock 138.650 MHz, 309 mm x 175 mm
1920 1968 2000 2080 hborder 0
1080 1083 1088 1111 vborder 0
+hsync +vsync
Manufacturer-specified data, tag 0
Manufacturer-specified data, tag 15
ASCII string: B140HAN01.2
Checksum: 0x37
EDID block does NOT conform to EDID 1.3!
Missing name descriptor
Missing monitor ranges

pathan421id
Posts: 24
Joined: Mon Jan 22, 2018 6:36 pm
Location: Ontario, CA

Re: T420s FHD Mod and BOE NV140FHM-N41 Panel

#4 Post by pathan421id » Tue Feb 20, 2018 4:10 pm

jal2 wrote:
Mon Feb 19, 2018 4:12 pm
I've found this specification on the web, too. But if I look into the EDID, also the one of the FHD mod (copied from B140HAN01.2 I guess) says "6 bits per primary color channel". Are the FRC bits transmitted in some separate eDP packets?
Main question is, if a simple update of the FHD mod PCB EDID would be enough to get the NV140FHM-N41 working with the FHD mod.

Here are the EDIDs again, decoded with edid-decode:
NV140FHM-N41 EDID wrote: Extracted contents:
header: 00 ff ff ff ff ff ff 00
serial number: 09 e5 37 06 00 00 00 00 03 18
version: 01 04
basic params: 95 1f 11 78 02
chroma info: 9d 40 9a 5d 55 8d 28 1e 50 54
established: 00 00 00
standard: 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01
descriptor 1: bc 39 80 18 71 38 28 40 30 20 35 00 35 ad 10 00 00 1a
descriptor 2: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1a
descriptor 3: 00 00 00 fe 00 42 4f 45 20 44 54 0a 20 20 20 20 20 20
descriptor 4: 00 00 00 fe 00 4e 56 31 34 30 46 48 4d 2d 4e 34 31 0a
extensions: 00
checksum: 31

Manufacturer: BOE Model 637 Serial Number 0
Made week 3 of 2014
EDID version: 1.4
Digital display
6 bits per primary color channel
DisplayPort interface
Maximum image size: 31 cm x 17 cm
Gamma: 2.20
Supported color formats: RGB 4:4:4
First detailed timing is preferred timing
Established timings supported:
Standard timings supported:
Detailed mode: Clock 147.800 MHz, 309 mm x 173 mm
1920 1968 2000 2200 hborder 0
1080 1083 1088 1120 vborder 0
+hsync -vsync
Manufacturer-specified data, tag 0
ASCII string: BOE DT
ASCII string: NV140FHM-N41
Checksum: 0x31

Unknown extension block

EDID block does NOT conform to EDID 1.3!
Missing name descriptor
Missing monitor ranges
FHD mod EDID wrote: Extracted contents:
header: 00 ff ff ff ff ff ff 00
serial number: 30 ae a3 40 00 00 00 00 0c 19
version: 01 04
basic params: 95 1f 11 78 ea
chroma info: 85 45 a4 5a 54 a1 27 0c 50 54
established: 00 00 00
standard: 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01
descriptor 1: 29 36 80 a0 70 38 1f 40 30 20 35 00 35 af 10 00 00 1e
descriptor 2: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
descriptor 3: 00 00 00 0f 00 d1 09 3b d1 09 3b 1e 0a 00 06 af 3d 12
descriptor 4: 00 00 00 fe 00 42 31 34 30 48 41 4e 30 31 2e 32 20 0a
extensions: 00
checksum: 37

Manufacturer: LEN Model 40a3 Serial Number 0
Made week 12 of 2015
EDID version: 1.4
Digital display
6 bits per primary color channel
DisplayPort interface
Maximum image size: 31 cm x 17 cm
Gamma: 2.20
DPMS levels: Standby Suspend Off
Supported color formats: RGB 4:4:4, YCrCb 4:2:2
First detailed timing is preferred timing
Established timings supported:
Standard timings supported:
Detailed mode: Clock 138.650 MHz, 309 mm x 175 mm
1920 1968 2000 2080 hborder 0
1080 1083 1088 1111 vborder 0
+hsync +vsync
Manufacturer-specified data, tag 0
Manufacturer-specified data, tag 15
ASCII string: B140HAN01.2
Checksum: 0x37
EDID block does NOT conform to EDID 1.3!
Missing name descriptor
Missing monitor ranges
I'm not sure where FRC is processed (either on the screen itself or on the controller). But the packets are not separate afaik.

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