exxos's Atari, Amiga & retro forum

@hunsra

Damn, completely overlooked the fact that Falcon's CPUs are 33x4 chips... :oops:

So you would have to directly solder the new chip once the old one removed.

If you're not sure to do that, better then to properly repair the broken pads.

@HigashiJun

Ah, too bad. I was hoping to use a socket. I guess that's off the table.

I've never removed a component with this many pins before, but I'll give it a shot and post the outcome.

Thanks again!

You could grind back the ceramic package with a Dremel to expose the internal metal of the legs and then solder bodge wires.

stephen_usher wrote: 20 Oct 2023 16:21 You could grind back the ceramic package with a Dremel to expose the internal metal of the legs and then solder bodge wires.

+1

I think that's worth a try considering the CPU is likely going to end up coming out anyway.

Thanks @stephen_usher and @exxos . I'll give that a try. I have already ordered a replacement CPU, but it can't hurt to have a spare if the existing CPU can work.

More progress and a problem:

I decided to remove the CPU rather than Dremel the plastic and wire the pins because I suspected the pads on the board were not right. Here are the images I took as I did the de-soldering:


It appears that I mangled the pads for pins 16 and 17 in the process of removing the CPU and cleaning the left-over hot glue from pad area. The following image shows the original pad layout and the next image shows the bodges I think I need to make. Does this seem correct? Any recommendations on where to attach the bodge wires, especially for pin 16?


Thanks!

Check here:

viewtopic.php?f=29&t=3300&start=40

For the first pad (pin 16), you will have to scratch the silkscreen in order to disclose the trace and solder your new copper pad to it.

(According to your picture, it seems that a part of this trace is already disclosed and you can solder onto it if you manage to make it flat again without breaking it).

The second pad is less problematic, as the trace is just near it on the left. Just scratch it and solder onto the disclosed copper.

HigashiJun wrote: 26 Oct 2023 08:45 For the first pad (pin 16), you will have to scratch the silkscreen in order to disclose the trace and solder your new copper pad to it.

Or trace where the trace goes to find either a chip or a via and then solder a bodge wire from the pin on the chip to the via or other chip pin. Far easier and safer. (Pin 16 is /BG so relatively low frequency so safe to use with a reasonably long bodge wire.).

Similarly, for pin 17 (/BGACK), a bodge wire between the via and the chip pin would be the easiest and safest option.

Also make sure to thoroughly scrape away those two destroyed pads, last thing you want is remnant traces of conductive pad causing havoc.

Thanks @HigashiJun, @stephen_usher, and @Steve! Such great advice from this group!

I'd ideally like to put new pads on the board, but I don't think I have the skill for that. I looked at the other forum post and found the info on replacement copper rivets for through-hole pads, but I couldn't find the information about new surface mount pads (I probably need to look again). I think I'd be more successful trying to bodge a wire from the via near pin 17, and a wire from an IC pin or component lead along the path of the trace for pin 16. I'll post progress pics once I figure out where I should connect pin 16.

Thanks again, folks!