Terminating cheapo SCA -> 50Pin SCSI adapters

[uniserver]

lol i like it!

good job bob

 

[uniserver]

I have bought 2 so far, they work good.

2 more are on the way to me

Thanks max

did you have an ad in trading post?

 

[Trash80toHP_Mini]

Woohoo, it's getting better and better with every iteration of your R&D efforts there, max! :approve:

 

[max1zzz]

Thanks Just glad people find them usefull

uni, yeah, just updated it with more accurate postage prices

And i have a question, how critical is the value of the termination resistiors? i would like to use resistior packs but 110ohm ones are dam near impossible to find.

I have a laptop -> desktop scsi adapter here that uses 150 ohm resistiors that seems to work fine, however 9 element 150ohm packs are just as hard to find

 

[max1zzz]

Thinking this is a good tradeoff between neatness and ease of assembly

This used 2 8 element packs and 2 through hole resistors (damn 9 element packs are hard to find)

 

[uniserver]

i like it.

hey anything that makes your life a little easier buddy!

 

[max1zzz]

Well, i think these 8 element packs work out really nicely:

[attachment=0]photo(14) copy.jpg[/attachment]

Even neater than the SMD's i think

 

[uniserver]

is the cost a little more +/- ?

 

[max1zzz]

Little more, they cost maybe 10p each, but not enough that I would charge any more for the adapters

There just easier to solder than the SMD's

I'll still do the adapters with SMD's if anyone wants though

 

[max1zzz]

So, since my last post uniserver brought my attention to the fact the price of these adapters have skyrocketed (hopefully this will only be a temporary thing), and as i only have 3 left i decided to look into the viability of producing a proper PCB for these

After a bit of fiddling in EAGLE (and a lot of swearing at it keeping joining electrical connections for no good reason) i ended up with this:

[attachment=0]Screen Shot 2014-01-26 at 16.13.18.png[/attachment]

It needs a bit of neatening up and having the silkscreen added, but it all fits (just about) (btw, a few of the scsi data traces look shorted in that, they aren't it's just how it looks in that pic)

Weather or not this will turn out to be viable is still to bee seen, PCB production prices are so high in the UK if i had them made here it would push the price to something like £20 each. So i guess i will look at pcb fabrication services in the US to see if i can get a better price

 

[max1zzz]

Don't suppose anyone here knows where i could get hold of some of the sca connectors? digikey has them, but at ~£7.50 each + £12 shipping to the uk it's a bit steep

Looks like pcb manufacture isn't going to be too bad, so i'm gonna refine the board a bit more and put in a order later this week

just finding those dam SCA connectors....

 

[uniserver]

you will have to get your SCA connectors direct from china…you might have to buy them 1000 or 2000 at a time…

but for pennies each..

i am one step away from buying my caps direct from china… and bypassing mouser all together.

the savings is mind boggleing. like some caps are .0003 ea LOL!

 

[max1zzz]

Yeah i was thinking of that, where would the best place be to get them for china? normally i order my Chinese parts off ebay but there's none on there

either that or i'll buy a bunch or the cheap 68 - 80 pin adapters and use hot air to sweat the connectors off, i don't want to do that but it should be possible

 

[uniserver]

ok here is the guy that i was buying my SCA to 50 pin adaptors from…

http://www.ebay.com/itm/SCA-80-ADAPTER-TO-68-PIN-ULTRA-SCSI-II-III-LVD-SE-C-/280498842646?pt=US_Drive_Cables_dapters&hash=item414f08ac16

i see he is selling a SCA adaptor for the same price… 1.61 but…. its SCA, but not to 50 pin scsi.

i cannot find SCA connectors for sale anywhere on the net.

maybe you will have to break down and make some calls to some factories in china….

 

[uniserver]

i sent him a message asking why he is not selling SCA to 50 pin any more...

 

[max1zzz]

maybe i'll have to do that

for now i think i'll just harvest some from the 68 - 80 pin boards

 

[uniserver]

i hear ya…

hey so will you sell me 2 more at the same price… i need 2 more..

 

[max1zzz]

Sure i have 3 more left

I need one for reference till i have the pcb's but you can have the other 2 at the normal price

 

[uniserver]

thanks man your the best.

 

[max1zzz]

Aha! found a uk supplier with the SCA connector -> http://uk.rs-online.com/web/p/pcb-sockets/7293842/

Not exactly cheap at £3.56 a piece, not listed as a SCA connector but my measurements make it the same

They will do for initial testing, once it comes to actually producing any for sale i'll harvest them from the Chinese boards