I'm posting this here since there does not seem to be a more fitting category.
The Device
The Gigaset DA810A is a landline telephone with an LCD screen, an answering machine and integrated telephone book. I have the version for the European (i.e. German) market.
It has two separate modules that can operate independently of each other: One is the basic telephony part that always works and is powered by the DC voltage coming through the telephone wire. It relies the TEA1110A telephone transmission and dialler chip for that.
The 'smart' part of the phone with the answering machine is powered via an external 7V power supply.
The system has two separate SoCs. One is built into the display unit and drives the LCD. It probably also stores the phone book. At least some of the phone controls are routed to it. That chip is covered in a black resin, making it hard to access and identify.
The other chip is on the main PCB and is accessible. It seems to be mostly specialized for DSP operations. It is e.g. connected to the room mic and speaker. That chip is identifiable, but seems to be rare or custom made. I was not able to find a data sheet anywhere. It has the label D56561AA3ALC.
The display chip seems to be unpowered when the external power supply is not plugged in, but starts up as soon as a call comes in or the receiver is lifted.
The Problem
After moving to a new home, the answering machine module has been acting up. When I plug in the external power supply it starts up fine and works, but after ~60s it resets, starts up again and repeats the same after 60s again.
What I did
I've been monitoring the voltages and oscillators for stability and have done an extensive analysis of the circuitry. So far I have not been able to find any particular faulty component and nothing seems to get hot.
I've also been trying to see interesting signals on my oscilloscope just before the reset on the DSP chip pins, but wasn't able to find anything conclusive.
I also grabbed the flash rom from the main board chip connected to the D56561AA3ALC, but the data seems encrypted, so I could not find anything useful there, easily.
My working theory is that the system waits for a resource or an event to happen until a timeout of 60s occurs, which causes an internal error condition to be flagged which in turn causes a self-soft-reset.
My problem is that I have limited knowledge about the SoCs that are built into the phone, so I can't easily tell what input they expect.
I could identify and get data sheets for almost all of the other ICs on the board. One is the MC34119, telephone amp, the others are flash chips (one for the Dsp chip, one for the display chip). The only one I could not identify was one labeled PT1103, but I'm pretty certain that this is an Amp for the room speaker.
You can find pictures of all the chips and both sides of the boards on Wikimedia, where someone was nice enough to upload all this: https://commons.wikimedia.org/wiki/C...Gigaset_DA810A
I have a slightly different board revision, but it's pretty much identical. Some parts of the board are hidden behind the electrolytic capacitors on the pictures, but most of it is visible.
Questions
If anyone here could provide me with a data sheet for the D56561AA3ALC, that would be great! If anyone has a sheet for the PT1103, I'd also be curious if my assessment was correct.
I would also appreciate any pointers to what else I could try to narrow the problem down.
Thanks a lot for any help!
Here are some of the annotations I made to the original Wikmedia images. I am happy to take additional pictures if required or provide data sheets etc.
![Click image for larger version
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The Device
The Gigaset DA810A is a landline telephone with an LCD screen, an answering machine and integrated telephone book. I have the version for the European (i.e. German) market.
It has two separate modules that can operate independently of each other: One is the basic telephony part that always works and is powered by the DC voltage coming through the telephone wire. It relies the TEA1110A telephone transmission and dialler chip for that.
The 'smart' part of the phone with the answering machine is powered via an external 7V power supply.
The system has two separate SoCs. One is built into the display unit and drives the LCD. It probably also stores the phone book. At least some of the phone controls are routed to it. That chip is covered in a black resin, making it hard to access and identify.
The other chip is on the main PCB and is accessible. It seems to be mostly specialized for DSP operations. It is e.g. connected to the room mic and speaker. That chip is identifiable, but seems to be rare or custom made. I was not able to find a data sheet anywhere. It has the label D56561AA3ALC.
The display chip seems to be unpowered when the external power supply is not plugged in, but starts up as soon as a call comes in or the receiver is lifted.
The Problem
After moving to a new home, the answering machine module has been acting up. When I plug in the external power supply it starts up fine and works, but after ~60s it resets, starts up again and repeats the same after 60s again.
What I did
I've been monitoring the voltages and oscillators for stability and have done an extensive analysis of the circuitry. So far I have not been able to find any particular faulty component and nothing seems to get hot.
I've also been trying to see interesting signals on my oscilloscope just before the reset on the DSP chip pins, but wasn't able to find anything conclusive.
I also grabbed the flash rom from the main board chip connected to the D56561AA3ALC, but the data seems encrypted, so I could not find anything useful there, easily.
My working theory is that the system waits for a resource or an event to happen until a timeout of 60s occurs, which causes an internal error condition to be flagged which in turn causes a self-soft-reset.
My problem is that I have limited knowledge about the SoCs that are built into the phone, so I can't easily tell what input they expect.
I could identify and get data sheets for almost all of the other ICs on the board. One is the MC34119, telephone amp, the others are flash chips (one for the Dsp chip, one for the display chip). The only one I could not identify was one labeled PT1103, but I'm pretty certain that this is an Amp for the room speaker.
You can find pictures of all the chips and both sides of the boards on Wikimedia, where someone was nice enough to upload all this: https://commons.wikimedia.org/wiki/C...Gigaset_DA810A
I have a slightly different board revision, but it's pretty much identical. Some parts of the board are hidden behind the electrolytic capacitors on the pictures, but most of it is visible.
Questions
If anyone here could provide me with a data sheet for the D56561AA3ALC, that would be great! If anyone has a sheet for the PT1103, I'd also be curious if my assessment was correct.
I would also appreciate any pointers to what else I could try to narrow the problem down.
Thanks a lot for any help!
Here are some of the annotations I made to the original Wikmedia images. I am happy to take additional pictures if required or provide data sheets etc.
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