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Help repair Huawei HG655B Router

Mr_Max

Member
Hi everyone

I have a Huawei HG655B router Board HG655BRZ Ver A, it has been working great since I flashed Firmware HG655b-B025 in 2015, a few days ago it suddenly died, I noticed that All LEDs went off except for the last one to the right (either USB or VOIP)I restarted the router using the side switch, hoping it will work but it didn't (All LEDs were off)
I tried Unbufferd Paralled Jtag cable that I had made, USBASP BRJTAG and I have tried many debrick utilities, the cpu is detected BCM6368 but the flash is never detected, I have triple checked the connections but no luck, the flash chip is S29GL064N, I don't know if it's supported by any of the debrick utilities I have tried(Zjtag 1.5-Brjtag 1.9o-Brjtag 2.0.5- Zjtag 1.0-Zjtag 1.8RC3). I have checked the voltages on different sections of the router board all seems ok 12v, 5V 3.3V 3V 1.25V, I have tried to backup flash with manual selection /fc:82 the closest one on most of the utilities was S29GL064M, I have attached the bin file I hope if anyone could check it, surprisingly its not empty. Unfounately there is no service manual or shcematic for this router, I have changed all the capacitors with new ones, removed the heatsink and re-flowed the BCM6368 chip still no luck, only the processor is identified with JTAG utilites (All LEDs off) and nothing on the serial connection ! Is it a hardware brick or soft brick ?! Any help would be greatly appreciated

HG655B Voltages.jpg

 
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narkeleptk

Member
If you read it before and not now then its likely the flash got damaged. If you have not read it with this tool before then it may just be looking in wrong area and flash is ok. I would think it more likely to be hardware issue, even if the flash is damaged.

With no schematics or any knowledge of the unit, I think you would need to have a working unit to compare with in order to repair.
 

Mr_Max

Member
If you read it before and not now then its likely the flash got damaged. If you have not read it with this tool before then it may just be looking in wrong area and flash is ok. I would think it more likely to be hardware issue, even if the flash is damaged.

With no schematics or any knowledge of the unit, I think you would need to have a working unit to compare with in order to repair.
Thanks a lot for your reply, yesterday it worked, but not for long, during probing flash chip and power cycles, I noticed that power LED turned on and the router booted normally, I was able to access it, when I tried to probe the flash chip using Jtag it was identified correctly then I tried to backup firmware, in the same way I did 5 years ago then the router failed again.
I wish to know if power Led is related to proper communication between the BCM6368 processor and the flash chip, or not ?!
If anyone have this model kindly check the voltage measurements to compare to mine
 
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narkeleptk

Member
It depends I guess. Some power lights will come on when plugged in and some not till something tells them too. The programming in the flash may control this but since it booted from poking around I doubt that it would be a software issue. Sounds like your programmer powered it up enough too boot so I would check to see if the the flash chips are getting proper supply to them.
 

unclejed613

Well-Known Member
Most Helpful Member
yesterday it worked, but not for long

sounds like something is failing from thermal problems. the board is 8 years old, it might actually be a dried out electrolytic cap in one of the regulators for the various voltages being used. the voltage would look correct with a multimeter, but if 10% of that is actually noise, the mpu or other devices will lock up. usually you don't want more than 2% of noise riding on a power supply (that would be 100mV on a 5V rail, or about 240mV on a 12V rail). any noise above 5% begins to cause random errors on digital systems.
 
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