Odd PCB pin configuration on 50-way IDC male header.

[Mr modnaR]

Hi all, another needle in a haystack question:

I'm looking for a 50-way idc male pcb header (think internal SCSI) but that fits into a 2mmx4mm grid instead of the usual 2.54mmx2.54mm. there's two rows spaced 4mm apart, and each pin in the rows is 2mm from its neighbour in that row. this hole configuration is currently being used by an external Centronics connector, and i assume this is why the pin arrangement is funky.

can anyone suggest a way of doing this? at the moment the options are:

1. make one

2. solder the ribbon cable directly to the board, but i'd rather not do this.

3. break into area 51 and steal some alien technology.

cheers in advance for any suggestions, no matter how weird and wonderful.

[fluke]

Find a broken drive/motherboard with it on and unsolder it from there?

[Mr modnaR]

interesting...

i'm not sure that there's any drives out there that have this pin arrangement as they're usually just straight pinned 2.54mm grid jobbies, but i'll certainly look into it! thanks for the suggestion.

[Wilba]

Just to clarify: you have a bunch of holes on a PCB in 2mm x 4mm spacing and need to connect a ribbon cable to it?

I would probably just take a strip of single row header pins (or double row, whatever was handy) and pull out the gold plated pin from the plastic and put them in the holes. Then use the crimp pins from a single row header connector without housing them in the plastic connector, maybe heatshrink each one.

The other option is soldering cable to the PCB, but only a short length, with a female IDC connector attached, so you can still unplug whatever you're connecting.

[Mr modnaR]

thank you , yes, i was thinking along the lines of two SIL headers, as i can get 2mm spaced pins from rs. it'd then mean getting sil IDC connectors, but i haven't really looked for those yet.

[TheAncientOne]

First off: Centronics is 36 pin, do you actually mean a 50 pin 'harmonica' connector?

(1) The easiest way would be to keep the 50 Pin board mounted socket, buy a 50Pin IDC plug, crimp a short length of ribbon into that, and then crimp a cable mounting 50 pin header on the other end, this is bulky but would work. 

Otherwise it's adapter time:

(2). Small PCB with drop pins, (nasty layout job), 

(3) Get a cable mount 50 pin IDC header crimp a short bit of ribbon on, and solder the other ends, (nasty soldering job).

I'd probably go for (3) if I really need the connector and the space, or (1) if speed was important.

Having had to look for something similar once, if you want the actual connector it's time for (Cue Music):

http://www.heatherlynn.net/Songs82/Mission_Impossible_Theme.mid

and don that black balaclave.......

(Quick edit to add - the problem has to do with a lack of 2mm pitch ribbon cable to go in aforementioned plug......)

Mike

[Mr modnaR]

First off: Centronics is 36 pin, do you actually mean a 50 pin 'harmonica' connector?

i guess so, i always understood these connectors to be called 'Centronics'

the connector at the moment goes from the pcb to one of these connectors on the back of my Akai S950, i want to convert it to a 50 pin 2.54mm pitch PCB header, so i can attach a 50-way IDC female socket and cable:

the problem is that the pin layout on the PCB is not 2.54mmx2.54mm, but 2mmx4mm.

[TheAncientOne]

So, the easy one is:

RS 235-6355 IDC 50 Pin SCSI plug

short 50 way ribbon, enough to go where you want,

then crimp on a

RS 121-0371 Cable mounting plug.

Job done - not too neat, but functional

Sorry I haven't got suitable pix to upload, you'll have to plug the numbers  into www.rswww.com to see what I mean

best I can come up with that's not  a pain to solder

Mike

[Mr modnaR]

i don't think i'm explaining myself correctly  ;D

what i currently have is a 239-1184

i want to take that out and replace with an IDC 'Centronics' panel mount socket (eg 239-1263 ) AND a pcb mount header (eg 625-7353)

so that i can add a length of cable between the pcb and the external connection with another IDC female socket on the cable to attach to an internal hard drive.

the problem is the pcb holes. i think i'm going to get two 25 way lengths of 2mm pitch pcb pins, and get two 25way cable mount sockets if there is such a thing!!  ???

[TheAncientOne]

OK, I guesss the main problem stems from the board being flat on the bottom of the case.

There is a bodge I once used, it's not nice, but it does work....

Buy two RS 334-549, or similar. These are wire-wrap pin header strips.

Cut to 25 way.

Spend some time bending the long wire-wrap pins to  line up with the PCB holes.

Fit both into a spare 50 way IDC cable socket (for alignment purposes). Fit to the board.

Solder the unit in place as close to the board as it will go, without unduly stressing the board.

(optional) I then put a fillet of hot-melt glue under the unit to give more support

remove the alignment plug

Make up a ribbon cable string for the connectors

Plug, and hopefully go.

Personally I think I'd do a loop cable  with IDC 50 Pin SCSI plgs and sockets, and slip the ribbon into the case by bending the lid a little if need be - I hate modifying original boards, I just like my mods to be reversible and easy to transfer. Comes of experience on the road with custom gear, so probably not applicable to your setup. If you;re taking custom gear on the road, build it to  MIL spec: hmm, perhaps the Area 51 option isn't that bad after all,

Mike

[Mr modnaR]

thanks for the help. yeah, the loop cable is what i'm going to use, though there's no need for it to go out of the case, the idc centronics connector will allow me to use external stuff. the whole plan behind this mod was to have an internal hard drive and flash card reader.

[TheAncientOne]

the whole plan behind this mod was to have an internal hard drive and flash card reader.

You've found a SCSI flash card reader?

I'd be very interested to find out about that as a boot source for a NAS unit I'm building.

Happy crimping.

MIke

[Mr modnaR]

well, technically, it's a PCMCIA reader, but i have a PCMCIA to CF card adapter  ;D

[smashtv]

Whee connectors with Unobtanium plated pins..... ;)

For an off-the-shelf solution, you might consider normal 2mm SIL pinheaders on the board, and two 2mm DIL IDC connectors on the cable placed close enough together that one of them connects only to the 25 in one row, with the other IDC connecting up the remaining 25.  This leaves one row of 25 on each IDC unconnected.

This is one of those things that is immediately understood when seen but hard to explain with text, so let me know if a better explanation is in order..... ;)

BTW: IDC SIL connectors that can use standard ribbon cable spacing live in the Unobtanium category also..... ;)

Best

Smash

[Mr modnaR]

lol @ unobtainium. thanks smash, i'll look into it.  ;D

[smashtv]

Hehe

That method is assuming studio use, though it would probably work fine forever (especially if you use dab of RTV to secure against vibration).

I have another method that is not too fiddly and would withstand tour (ab)use if needed.

Can you tell I have been more than once around the ride with non-standard connectors?  ;D

Best

Smash

[Mr modnaR]

Can you tell I have been more than once around the ride with non-standard connectors?  ;D

;D

[stryd_one]

Hmm...Why not put the flash reader in an external case and just hook that centronics up to it (like you would a normal hdd)?

Otherwise you could strip an external bay for the centronics to 50-pin on there...

unobtanium  LOL

[Mr modnaR]

AAAARRRRRGGGGHHHHH!!!!  ;D i want to keep it all internal. the connector you suggest wil be no good, as i need to put a ribbon cable in between the external socket, and the pcb it's attached to.