Thoughts on desoldering a component on a 30+ year old retro computer

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robjg63

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#2734226 25-Jun-2021 11:45

BlueOwl:

That pin is probably supposed to be missing.

I seem to remember that pin 3 was blanked on many insulation-displacement connectors and the pin was left out on motherboard headers to act as a kind of keying mechanism to prevent the connector from being attached the wrong way.

All of the odd pins are connected to ground, so having one missing wasn't a problem.

It certainly appears that there never was a pin going by that photo.

Nothing is impossible for the man who doesn't have to do it himself - A. H. Weiler

gbwelly

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#2734253 25-Jun-2021 12:51

frankv:

@gbwelly, I don't believe your arrow is pointing to the right connector on the reverse side? Your arrow points to holes that appear to be in a zig-zag pattern, not 2x17. I think that the tail of your arrow is pointing to the connector in question?

I'm not certain either, just going by OP's "The double row of pins just above centre are the header pins"

Lizard1977

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#2734519 25-Jun-2021 15:36

I wasn't sure if there was a pin there originally, to start with (I never paid that much attention) but checking photos of other Amiga 500s online shows clearly pins all the way.

As for the marked up photo with the arrow, it's not pointing at the right pin. It is level with the base of the arrow head, one in from the block of parallel soldered connections.

I'll find out tomorrow when I can take it into the Makerspace and take a proper look.

Lizard1977

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#2735680 28-Jun-2021 11:19

Well, it turns out that the pin is indeed supposed to be missing. The very helpful folk at the Makerspace showed that the solder point on the reverse side of the motherboard where the pin should have been was never actually soldered, so there's not supposed to be a pin there. But we were both still puzzled why we were able to find photos online of Amiga 500 motherboards where the floppy connector clearly showed 34 pins in place. Oh well, never mind.

I reassembled everything and it's all working fine. Which is still frustrating, as now I won't know what actually went wrong. My best guess is that I wasn't paying attention and hadn't plugged the connector in properly. But I'm sure (think I'm sure, at least) that I checked, and double checked. But in the absence of anything else, I'll just go with "I'm an idiot" for now.

gbwelly

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#2735683 28-Jun-2021 11:24

Lizard1977:

Well, it turns out that the pin is indeed supposed to be missing. The very helpful folk at the Makerspace showed that the solder point on the reverse side of the motherboard where the pin should have been was never actually soldered, so there's not supposed to be a pin there. But we were both still puzzled why we were able to find photos online of Amiga 500 motherboards where the floppy connector clearly showed 34 pins in place. Oh well, never mind.

I reassembled everything and it's all working fine. Which is still frustrating, as now I won't know what actually went wrong. My best guess is that I wasn't paying attention and hadn't plugged the connector in properly. But I'm sure (think I'm sure, at least) that I checked, and double checked. But in the absence of anything else, I'll just go with "I'm an idiot" for now.

Good on you for coming back to give me closure. Please enjoy your 'I told you so'. 😁

BlueOwl

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#2735704 28-Jun-2021 11:56

Lizard1977:

I reassembled everything and it's all working fine. Which is still frustrating, as now I won't know what actually went wrong. My best guess is that I wasn't paying attention and hadn't plugged the connector in properly. But I'm sure (think I'm sure, at least) that I checked, and double checked. But in the absence of anything else, I'll just go with "I'm an idiot" for now.

Possibly connected the wrong way around, which is easy to do with the old floppy driver connectors. If it is the wrong way around the drive activity LED stays on, and the drive refuses to do anything. Doesn't cause any damage.

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