Tiido wrote on 2022-08-29, 19:57:

I don't have any at hand and they're all packed away too to show (I'm in the middle of a move to another country) but there's basically just large solder pads underside so that pin headers could be soldered to them, all surface mounted fashion. They're pretty PITA to make that way but I couldn't find a better solution.

Tiido: Would you be willing to make more in the future? 32kx8 and 128kx8.

The solder pads are usually not very stable and can peel-off relatively easily, especially if we have leg-pins that insert into slots. The forces at play are much bigger than what individual solder pads are made for.
Did you damage some of the solder pads, or they hold well enough ?

pshipkov wrote on 2022-08-29, 18:08:

My point is that soldering pins on the bottom like that will be hacky and messy. […]
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My point is that soldering pins on the bottom like that will be hacky and messy.

Potential options:
1. A separate PCB with SOJ socket on it (or simply solder pads) that can be inserted vertically into the base one with the DIP pins using a SIPP-like connector. This way we can modularize the contraption. Feels like too much. Can be made simpler.
2. Make the PCB longer and move the SOJ chip and the solder pads to the side of the array with DIP legs. This will make the module unsuitable for some motherboards. Especially the ones with 2 columns of sockets.

I’m liking the way that others have done it. Smd pins suck but it is what it is and it looks nice.

If you want a vertical riser style that is also possible but I like the way the two examples are done with smd pins.

Another way is solder resistor leads and spider it out to the pin pads but that will probably look like crap

pshipkov wrote on 2022-08-29, 21:27:

The solder pads are usually not very stable and can peel-off relatively easily, especially if we have leg-pins that insert into slots. The forces at play are much bigger than what individual solder pads are made for.
Did you damage some of the solder pads, or they hold well enough ?

Covering the edges of the pads with solder mask can help a little if there is room.

There is one final way this can be done but it is not universal.

If we map out the locations of all the LIF pins and make one big pcb you could wire the new chip pads to straddle the sockets and just trim the through holes as flush as you can.

I had planned to make more but things never got that far, I have a bag of PCBs and pins though not the SRAMs needed. After move is done I can do some on request. (I have PCBs for 32 and 128KB chips)

I never experienced any delamination or other issues on the little boards. Once all pins are soldered down, it actually takes signifcant effort to damage the boards, the outer pins that hold alignment give significant mechanical stability.

Tiido: please put me on your PM list for whenever you get around to digging into your extra SOJ to DIP adapters. Thanks

I don't think the issue with the bent pin on a surface mount pad is all that detrimental. It is better than trying to do a vertical mount or get some 2x4 or 1x8 array PCB's made. However, if someone does create the larger PCB footprints for the array style, I think at least one interation should have SOJ sockets.

feipoa wrote on 2022-08-30, 04:28:

Tiido: please put me on your PM list for whenever you get around to digging into your extra SOJ to DIP adapters. Thanks

I don't think the issue with the bent pin on a surface mount pad is all that detrimental. It is better than trying to do a vertical mount or get some 2x4 or 1x8 array PCB's made. However, if someone does create the larger PCB footprints for the array style, I think at least one interation should have SOJ sockets.

For an array pcb you may as well just direct solder it and remove the motherboard sockets.

Is there any chance that the arrangement of these is in any way kinda standardized as in spacing?
Because if so then only four styles would be required right? Inline, side by side, more pins, less pins

Standardised? lol. I don't think so. Sometimes the orientation is flipped either on the module side or the column side. You'd need a more iterations than just 4. Also, for the TAG, you'd still need a single SOJ on DIP adapter, unless you want a 4-fold factor increase in iterations.

feipoa wrote on 2022-08-30, 04:42:

Standardised? 🤣. I don't think so. Sometimes the orientation is flipped either on the module side or the column side. You'd need a more iterations than just 4. Also, for the TAG, you'd still need a single SOJ on DIP adapter, unless you want a 4-fold factor increase in iterations.

Figured. Lol

@tiido
I will be interested in getting some as well.

If sphere478 or others here come with a better design that will be more than welcome too.

pshipkov wrote on 2022-08-30, 05:48:

@tiido
I will be interested in getting some as well.

If sphere478 or others here come with a better design that will be more than welcome too.

I think tiddo nailed it 😀 go with that.

Tiido wrote on 2022-08-29, 22:21:

I had planned to make more but things never got that far, I have a bag of PCBs and pins though not the SRAMs needed. After move is done I can do some on request. (I have PCBs for 32 and 128KB chips)

Would you share your gerbers for us to start playing with? I see you have solder pads for both 0805 and 0603, I think either one is enough. I also think to do as many mounted through round pins as possible for better reliability.

A User at dosreloaded also has a similar project.
128kx8

matze79 wrote on 2022-08-30, 06:18:

A User at dosreloaded also has a similar project. 128kx8 […]
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A User at dosreloaded also has a similar project.
128kx8

madao.jpg

https://dosreloaded.de/forum/index.php?thread … 7704#post167704

this thread turned out well 😀 haha

That is actually exactly what I was thinking of for a vertical daughter board style. Can't tell if they jigsawed it together or not though. my thought was to make a hole in the bottom for stability.