exxos's Atari, Amiga & retro forum

Rustynutt wrote: 26 Sep 2023 23:23 BTW, Best Electronics sells the VIDEL, COMBEL or SDMA for $45 each.

Rustynutt wrote: 27 Sep 2023 05:47 That's for a bulk lot :)

alexh wrote: 27 Sep 2023 15:40 I think the Exxos PSU has short detection but better to test than accidentally burn a track or two first power on.

alexh wrote: 27 Sep 2023 15:40 Might be worth performing a test for power <-> gnd shorts just before you switch on? Just in case anything has become a short. It just takes a fleck of solder dropped while someone was removing something.

I think the Exxos PSU has short detection but better to test than accidentally burn a track or two first power on.

You seem experienced so I'm sure you are planning to do it.

exxos wrote: 27 Sep 2023 15:56

alexh wrote: 27 Sep 2023 15:40 I think the Exxos PSU has short detection but better to test than accidentally burn a track or two first power on.

It has a "soft start". Think it's current limited to 1amp during power up. If the voltage doesn't rise it trips short-circuit protection. Basically doesn't shove full amps at power on like most PSUs tend to do. The slower ramp up means it shouldn't vaporise tracks and can help limit abuse to silicon also.

• First, I checked the power rails and traces for continuity with a multimeter and there seem to be no shorts (thanks to @alexh for the suggestion).
• Programmed and installed the missing GAL (see photos).
• The original CMOS chip had been cut out instead of desoldered (see photos), so I removed all of the pins left in the board. This was more difficult than I expected. A few pins required significant heat and time to remove. I assume this is due to those pins being connected to a large ground plane area. I was able to finally get them all out without any apparent damage.
• Installed a low-profile DIP socket for the CMOS chip (see photos).
• Removed the CPU mod remains. Doing this snapped the bent pins from the CPU (see photos). I have doubts that this is repairable, but I'll ask the forum for advice: should I replace the CPU or try to attach leads to the broken pins and traces? If I replace, is there any way to socket a CPU with this board?

HigashiJun wrote: 20 Oct 2023 06:36 Repairing your CPU pins is doable, but it wouldn't be a neat job if done with wires.

In this case, it would be better to de-solder the CPU with a hot-air station and then fit a SMD socket and a new CPU.

But of course, it's up to you and your abilities.