Troubleshooting Circuitry in Old SD49225T-HN PTZ Cameras

Did two experiments today.

1. Test what happens if you power up the camera without an EEPROM in place? Is there a copy of the firmware in the battery backed up RAM?

Result - Camera powers up and then the PTZ system does its horizontal and vertical motion motions. However, the camera does not appear at any IP address. So, no it cannot boot up without the EEPROM. The EEPROM carries the active copy of the firmware. Whatever is in battery backed up RAM does not act as an extra copy of the firmware. This also suggests that one cannot install a blank EEPROM into the camera. It has to be programmed with the firmware.

I suspect they DO install the EEPROM and then program it in circuit at the factory, but none of us knows how to access the UART (assuming there is such an access for programming)

With the XGecu T48, I should be able to clone the old EEPROM to a new chip before soldering in the new one. At least, that is my plan.


2. Verify XGecu T48 functionality. Since, I don't have a TSOP 48 adapter for this programmer, I needed another format EEPROM to test the programmer. Desoldered a M25P10 8 pin EEPROM from a dead hard drive board. Got it onto a TSOP 16 adapter and YES! The T48 programmer can read, erase and program the M25P10 EEPROM. The programmer works.

Going to be a LONG wait for the right TSOP48 to T48 programmer adapter to arrive.
 
guykuo said:
Did two experiments today.

1. Test what happens if you power up the camera without an EEPROM in place? Is there a copy of the firmware in the battery backed up RAM?

Result - Camera powers up and then the PTZ system does its horizontal and vertical motion motions. However, the camera does not appear at any IP address. So, no it cannot boot up without the EEPROM. The EEPROM carries the active copy of the firmware. Whatever is in battery backed up RAM does not act as an extra copy of the firmware. This also suggests that one cannot install a blank EEPROM into the camera. It has to be programmed with the firmware.

I suspect they DO install the EEPROM and then program it in circuit at the factory, but none of us knows how to access the UART (assuming there is such an access for programming)

With the XGecu T48, I should be able to clone the old EEPROM to a new chip before soldering in the new one. At least, that is my plan.


2. Verify XGecu T48 functionality. Since, I don't have a TSOP 48 adapter for this programmer, I needed another format EEPROM to test the programmer. Desoldered a M25P10 8 pin EEPROM from a dead hard drive board. Got it onto a TSOP 16 adapter and YES! The T48 programmer can read, erase and program the M25P10 EEPROM. The programmer works.

Going to be a LONG wait for the right TSOP48 to T48 programmer adapter to arrive.
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PROGRESS!!! Take the little wins, Who knows, a year from now you might be running Guykuo's P.T.Z. repair services. :winktongue: Working on circuits with no schematics can suck, frustration, but very satisfying when you gain some insight. This is really Groundbreaking stuff because there is very little known about the Inner workings of these cameras. So you did really learn something, Someplace there has to be a embedded Rom for doing its first POST and running the presets? Those commands have to come from someplace.
Once it passes those (I'm Guessing now)it goes out and looks for the Operating system. Hopefully its all on the EEPROM. Hopefully you will get a good image from it and gain Insight in the workings from it. I'm really rooting for ya.
 
guykuo said:
Going to be a LONG wait for the right TSOP48 to T48 programmer adapter to arrive.
Click to expand...
You seem like someone who could solder some tiny wires to an eeprom and wire wrap them to a dip socket that drops into the ZIF socket.
 
After a long time, I'm bringing this topic up again because I still have my SD49225T-HN lying around dismantled and I'm wondering whether I should throw it away or whether something can still be done.

@guykuo I don't remember all of your posts here, but have you ever managed to get one of your SD49225T-HNs to stop rebooting on its own so that it functions normally again? If so, how exactly, and would a good DIY enthusiast be able to do it without replacing various parts of the motherboard? For example, by just replacing a capacitor on the board, or just the Seiko ML Lithium Rechargeable Battery ML414H you mentioned?

It would be a shame to throw away the camera just because it resets every now and then, but otherwise still works perfectly. :)
 
Jim_OS said:
After a long time, I'm bringing this topic up again because I still have my SD49225T-HN lying around dismantled and I'm wondering whether I should throw it away or whether something can still be done.

@guykuo I don't remember all of your posts here, but have you ever managed to get one of your SD49225T-HNs to stop rebooting on its own so that it functions normally again? If so, how exactly, and would a good DIY enthusiast be able to do it without replacing various parts of the motherboard? For example, by just replacing a capacitor on the board, or just the Seiko ML Lithium Rechargeable Battery ML414H you mentioned?

It would be a shame to throw away the camera just because it resets every now and then, but otherwise still works perfectly. :)
Click to expand...
Hi
I managed to get the camera working again. All the symptoms posted on this forum had the camera. Apparently, NAND memory has a limited lifespan, so the problem lies in this. I bought the NAND programmer and a friend who is an expert in that helped me repair it.
 
Thanks for the info. But NAND flash memory is a flash memory chip, and if I had to replace it, it would have to be desoldered. That would be too much work for me, or rather, I wouldn't be able to do it at home with the resources I have. But in my mint it's certainly unusual for a flash memory chip to fail after 5, 6, or 7 years. But who knows what Dahua used and installed. :lol:

OK - let's see if guykuo gets in touch and tells us what his experiences and results were with his repair attempts. :)
 
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