- Panasonic LED TV using Hisense 5730 Mainboard with Cannot Start-up Problem

Panasonic LED TV using Hisense 5730 Mainboard with Can’t Start-up Problem

This TV repair tips is provided by Au Yang. The customer bring this Hisense 5730 Mainboard (p/n: RSAG7.820.5730/ROH) to repair with complaint the Mainboard cannot startup or can’t power on. This 5730 TV Mainboard their mainchip is using the MSD6A918, EMMC is Toshiba 5G5A1, have 4 external DDR RAM. The mainchip left side have two DDR ram as DDR0 and the mainchip top side DDR RAM is as DDR1.

panasonic tv with hisense mainboard 5730

First, check TV Mainboard all voltage supply lines and all are normal. This TV mainboard is use the 12V supply. Connect the RT809H Universal Programmer to their ISP port. Power on the TV and found their Startup Print Log is shows as below:

tv cannot start-up problem

With the above photo shows that their DDR0 or corresponding components/circuit is abnormal. The DDR0 is use as BootLoader, located the mainchip left side (two DDR rams). Check these DDR ram supply voltage is 1.5V normal, reference voltage is 0.749V normal, also their feedback voltage line normal.

Second step is to check their communication lines in between the DDR and mainchip. Power off the Mainboard, use multimeter Diode range, Red probe connect to Ground, and Black probe check their pins. Normally, it is checking their network resistor pins (this network resistor is located in between the DDR and mainchip). Found the network resistor RP13, one of the pin values compare to other was different so much. Please look at the photo below:

check tv mainboard ddr communication lines

check ddr to mainchip lines

After that, check the mainchip side diode range values is like photo below:

check panasonic tv with hisense mainboard

So their both side different about 60 plus, but the network resistor their each resistor is just about 22 ohm only. So it is something wrong about it. Check the network resistor each ohm values and found that pin (one of the pin ohm values is out) ohm values is abnormal. Replaced the RP13 network resistor, connect again to the RT809H programmer and check their Startup Log as below:

COM4, BaudRate:115200 bps, RXD: VGA->11,TXD: VGA-> 4, Printed by RT809H: UART_115200AC_ONBIST0-OKBIST1-OK_URelocation Offset is: 01500000[AT][MB][start ub][725]U-Boot 2011.06-00041-g5014ffe-dirty (Nov 08 2014 - 00:21:26)[35m[NOS] UtopiaInit[m1st UTOPIARegisterToUtopia is done[35m[MBoot] Driver Register to Utopia[muboot held at [343ddf60~35700000]CPU : NapoliBoard: BD_MST051D_20ANV_NAPOLI_CUS18DRAM: 343 MiBNow running in RAM - U-Boot at: 34800000eMMC: HS200 200MHz eMMC 3.68 GB [75FFF8h] 。。。。。

“UART BUS OFF!!”

It looks like UART console is OFF or disable. The Hisense 5730 TV Mainboard is stuck in logo problem now!

panasonic tv hisense mainboard stuck in logo problem

So, it is need to ON the UART first. Fly 4 wire to TV mainboard CLK, CMD, D0, GND and disconnect the CLK resistor.

connect with RT809H programmer flying 4 wire

Another side of 4 wire connect to RT809H programmer. Use the RT809H single EMMC Mstar solution, to open/ON their UART write function. The UART is ON now as photo below:

rt809h startup log

After ON the UART, use the USB thumb drive with their correct version of firmware and upgrading it. After successful upgrade their firmware, the TV Mainboard still same problem stuck in startup logo there. So decided to replace their mainchip 6A918. After replaced the mainchip MSD6A918, the TV mainboard is working perfectly.

replace the mainchip MSD6A918 IC