VOGONS


First post, by rasteri

User metadata
Rank Member
Rank
Member

I've been playing with PC104 CPU boards recently and was frustrated by how expensive it is to plug an ISA card into them. Most adapters are more than $100 and that seems ridiculous when you could probably make your own adapter reasonably easily using IDC connectors and ribbon cable.

But I was doing a big PCB order anyway so decided to spend a couple hours knocking up some boards, cost each less than $20 :

pc1041.jpg
Filename
pc1041.jpg
File size
977.25 KiB
Views
1083 views
File license
Public domain

The small one leaves access to the main board but means that the card lies outside the PC104 footprint :

pc1042.jpg
Filename
pc1042.jpg
File size
1.9 MiB
Views
1083 views
File license
Public domain

The large one sort of folds the ISA card back on top of the PC104 board and is probably more useful if putting the assembly in an enclosure :

pc1043.jpg
Filename
pc1043.jpg
File size
1.41 MiB
Views
1083 views
File license
Public domain

I tested them and they work great! Here's a video of my old Ensoniq Soundscape Opus running on an Advantech PCM-5890 :
https://www.youtube.com/watch?v=ww3rUIURMVM

Gerbers for the boards can be found here (your fab house will need to be able to do 5mil trace/space) : http://rasteri.com/ISA_PC104_Adapter_Gerbers.zip

And the source CAD files are in Altium Circuitmaker's cloud : https://circuitmaker.com/Projects/Details/ras … o-PC104-adapter

This is just the first revision so don't go plugging anything irreplacable into it until I've done more testing, but they seem to work perfectly for me on all the cards and motherboards I've tried. There's no decoupling capacitors or anything since I figure most ISA cards will have plenty on board, and the traces aren't very long anyway. The power traces are thicker than the data traces but they could perhaps be even thicker, I don't know how much current an ISA slot is expected to cope with.

The designs are public domain, do with them as you wish.

Reply 2 of 11, by dekkit

User metadata
Rank Newbie
Rank
Newbie

Just wanted to say many thanks for your work and for sharing the gerbers for this (and your other projects while I'm at it).

I'm in the process of converting a small industrial socket3 486 mainboard into a mini dos rig and I can now add a cheaper isa sound card thanks to this! (I'm using the smaller one). I may have a few left over spares if anyone is doing similar.

dek

Updated 26/5/2022 - thanks was able to get an ESS soundcard working great on my SBC!

20220521_163505~2.jpg
Filename
20220521_163505~2.jpg
File size
503.57 KiB
Views
794 views
File license
CC-BY-4.0

Reply 6 of 11, by weedeewee

User metadata
Rank Oldbie
Rank
Oldbie

there's a url visible, on a photo, on the connector. Looks like a good source.

Right to repair is fundamental. You own it, you're allowed to fix it.
How To Ask Questions The Smart Way
Do not ask Why !

Reply 7 of 11, by imi

User metadata
Rank l33t
Rank
l33t
rasteri wrote on 2022-06-09, 12:29:
imi wrote on 2022-06-09, 10:42:

where do you source the right angle ISA connectors?

Digikey... part number EBC49DCAN-S605

thanks, a bit pricey 😁

@weedeewee 🤣 I didn't even pay attention to that, yeah it seems the one on digikey is from sullins.

Reply 9 of 11, by dekkit

User metadata
Rank Newbie
Rank
Newbie

The SBC im working with can be found here:

Help with mapping out a Single Board Computer (SBC) - 486-DX2-80 - Innovative Technologies, Houston, Texas

It had zero documentation available for it, and very little written on the pcb. So I've slowly been mapping out the pins based on the datasheets for the IC s and making a few educated guesses based on similar era SBC and socket 3 boards (all my notes are documented in the link). Ive got it to a useable state now, so I'll finish documenting what I know and build a case.

As for parts for the PC104 adapter above (blue one in the pic above):

PCB = ordered via Jlcpcb ~$20 AUD x5 (small boards) posted via slow slow mail.

The sockets were cheap from Aliexpress (with a bit of research of pc104/isa layouts, mixing and matching of parts, and also bit of luck):

For the ISA part~ $20 aud (incl post)
5x "2.54mm pitch curved edge connector slot" (2x 31p)
5x "2.54mm pitch curved edge connector slot" (2x 18p)
- take note of orientation in pics.

For the IDC part that connects to pc104 ~$15 aud (incl post)
5x PC104 2.54mm Female stacking header for dual row..." (2x32p)
5x PC104 2.54mm Female stacking header for dual row..." (2x20p)

By far the hardest part was soldering the pins of the otherside of the pc104 (as its tricky to get the iron around when you have all idc rows next to each other) - so if I do this again, next time it may be easier to order single rows (ie 1x 32p) of female stacking headers.

So all up it was about $55 AUD for parts (which took weeks to arrive) and an afternoon of soldering to build 5 x units.

So significantly cheaper than buying an industrial adapter and perfect for my personal 486 gaming rig.

Hope that helps!

Last edited by dekkit on 2022-06-12, 12:33. Edited 1 time in total.

Reply 10 of 11, by rasteri

User metadata
Rank Member
Rank
Member
dekkit wrote on 2022-06-12, 12:18:

By far the hardest part was soldering the pins of the otherside of the pc104 (as its tricky to get the iron around when you have all idc rows next to each other) - so if I do this again, next time it may be easier to order single rows (ie 1x 32p) of female stacking headers.

Yeah it is a bit tricky - I have a video guide showing how I do it here - https://youtu.be/6cXdWMOl8QE?t=440

Reply 11 of 11, by dekkit

User metadata
Rank Newbie
Rank
Newbie
rasteri wrote on 2022-06-12, 12:24:
dekkit wrote on 2022-06-12, 12:18:

By far the hardest part was soldering the pins of the otherside of the pc104 (as its tricky to get the iron around when you have all idc rows next to each other) - so if I do this again, next time it may be easier to order single rows (ie 1x 32p) of female stacking headers.

Yeah it is a bit tricky - I have a video guide showing how I do it here - https://youtu.be/6cXdWMOl8QE?t=440

Yep, had to change soldering tip to the smallest I had and use a healthy amount of soldering flux to get it to flow! Good video to reference.

(Was also contemplating making the pc104 soundcard you designed - nice work there too!)

Thanks again for releasing your pcbs - most appreciative!