Trying to repair a dead TF530

[root42]

So I got a broken TF530 last year. I want to get it flying again. What I did:

* Checked the contents of the CPLDs -- they are fine and match the latest firmware
* Reflowed the ICs, because some legs looked a bit corroded.
* Checked clock, address and data bus with scope
* Tried to run it with the CPU relocator and with my Lazarustorm (without relocator, on the expansion bus)

My findings: For a short while I got a yellow screen (CPU exception) but now all I get is black screen. I do see activity on the bus, I guess the CPU tries to execute code. However some of the RAM address lines look wonky. CE also looks weird, it's at 3.7V, which I would say is too low -- or too high, depending what you are expecting. And I would expect it to toggle regularly...

Currently I would suspect the SRAMs to be bad. But are there any other things I should be watching out for? Is it possible to disable the SRAM completely and try to boot only with the installed 512K?

[alenppc]

So I got a broken TF530 last year. I want to get it flying again. What I did:

* Checked the contents of the CPLDs -- they are fine and match the latest firmware

There is no such thing as the "latest firmware" on the 530. The 530 was very much experimental with a wide variety of firmwares that need to be flashed according to what oscillator you have installed. Also, there are different firmwares for rev 2 and rev 3, so make sure you are using the correct one for your board and crystal.

Currently I would suspect the SRAMs to be bad. But are there any other things I should be watching out for? Is it possible to disable the SRAM completely and try to boot only with the installed 512K?

You can erase the RAM cpld to accomplish this.

[root42]

I took the binaries repo and picked the latest rev3 firmware. My TF at least has Rev3 printed on the PCB.

I will try to erase the CPLD, good idea!

[alenppc]

I took the binaries repo and picked the latest rev3 firmware. My TF at least has Rev3 printed on the PCB.

I will try to erase the CPLD, good idea!

I had all of the 530 firmwares but unfortunately lost them in a hard drive crash. But there is a strong chance you might be using a firmware designed to run at a different clock speed. What is the onboard oscillator?

[root42]

I took the binaries repo and picked the latest rev3 firmware. My TF at least has Rev3 printed on the PCB.

I will try to erase the CPLD, good idea!

I had all of the 530 firmwares but unfortunately lost them in a hard drive crash. But there is a strong chance you might be using a firmware designed to run at a different clock speed. What is the onboard oscillator?

33 MHz. Using the firmware from here:

https://github.com/terriblefire/terribl ... ster/tf530

[alenppc]

I don't remember which speeds these were for. Some would only run at 25, some only at 50 and some did a range of approx. 36-50... I would recommend you try flashing different versions and see if some of those work.