Thread
Terminating cheapo SCA -> 50Pin SCSI adapters
As requested I took some pictures building the Mark 2 of these adapters so anyone interested could put them together
Parts:
Chepo 80Pin SCA to 50 Pin adapter (http://www.ebay.co.uk/itm/130772715339)
18x 110ohm resistors, i suggest you use 1/8 watt or you will be pushed for space (1/4 should just about be ok) (http://cpc.farnell.com/_/mf25-110r/resistor-0-25w-1-110r/dp/RE03728)
OR 110 Ohm resistor packs pulled from dead drives
1x 1N4001 diode (or anything similar) if your adapter doesn't have a diode on it already you will need 2 (though i haven't seen any without it)
1x Small electrolytic cap (I used a 10uF non polarized one, any small value should work, and it dosen't need to be NP, just the ones i have are)
Total cost of the parts should be under £2
This adapter just terminates the lines on the 50 pin connector, it will not help with any fussy SCA drives that want their extra data lines terminated.
First thing is to solder the 110 ohm resistors, Connect all the tops of them together:
Then the cap, which goes between the the common contact of the resistors and ground, i find the best thing is to fold the legs other tho the other side of the board:
And finally, solder the diode between the side of the term power jumper closest to the edge of the board and the common contact of the resistors. Cathode towards the resistors.
Also I recommend you cut the trace going from the term power to the 50 pin connector, otherwise you may find in some macs you cannot switch off termination.
Installed and it works
Parts:
Chepo 80Pin SCA to 50 Pin adapter (http://www.ebay.co.uk/itm/130772715339)
18x 110ohm resistors, i suggest you use 1/8 watt or you will be pushed for space (1/4 should just about be ok) (http://cpc.farnell.com/_/mf25-110r/resistor-0-25w-1-110r/dp/RE03728)
OR 110 Ohm resistor packs pulled from dead drives
1x 1N4001 diode (or anything similar) if your adapter doesn't have a diode on it already you will need 2 (though i haven't seen any without it)
1x Small electrolytic cap (I used a 10uF non polarized one, any small value should work, and it dosen't need to be NP, just the ones i have are)
Total cost of the parts should be under £2
This adapter just terminates the lines on the 50 pin connector, it will not help with any fussy SCA drives that want their extra data lines terminated.
First thing is to solder the 110 ohm resistors, Connect all the tops of them together:
Then the cap, which goes between the the common contact of the resistors and ground, i find the best thing is to fold the legs other tho the other side of the board:
And finally, solder the diode between the side of the term power jumper closest to the edge of the board and the common contact of the resistors. Cathode towards the resistors.
Also I recommend you cut the trace going from the term power to the 50 pin connector, otherwise you may find in some macs you cannot switch off termination.
Installed and it works
nice! 
i like home brew stuff like this!
i like home brew stuff like this!
you are the man hard core, i love it
hard core, i love it
Thanks glad i could contribute something usefull
and i should have probably noted, the contacts you solder the resistors to are:
r r r r r r r r o r o o o o o o r r r r r r r r r
o o o o o o o o o o o o o o o o o o o o o o o o o
(that is with the 50 pin connector towards you) r = resistior o = no resistior
glad i could contribute something usefull and i should have probably noted, the contacts you solder the resistors to are:
r r r r r r r r o r o o o o o o r r r r r r r r r
o o o o o o o o o o o o o o o o o o o o o o o o o
(that is with the 50 pin connector towards you) r = resistior o = no resistior
i wonder if we could neaten it up and use surface mount stuff?
yes, let me take pics of my one using resistor packs from a dead 120mb quantum pro drive ELS it is much much neater
I did consider using SMT parts, however i find they are very fiddly in situations like this, However an interesting idea would be to produce a small cuircuit board using smt parts, with pads right at the edge of the board. Then you could just stick the board down and solder it right to the pins, easy and neat (like the QSB's used in the xbox modding community)
EDIT: Here is mk1, using the res packs, however it is permanently terminated
I did consider using SMT parts, however i find they are very fiddly in situations like this, However an interesting idea would be to produce a small cuircuit board using smt parts, with pads right at the edge of the board. Then you could just stick the board down and solder it right to the pins, easy and neat
(like the QSB's used in the xbox modding community)EDIT: Here is mk1, using the res packs, however it is permanently terminated
Another option is to use an external IDC-50 terminator on the end of the SCSI cable.
Yep, that is another good option, passthrough 50 pin terminators are a good option aswell
Just had been wondering for a while how easy it would be to make a terminated adapter, and the answer is very easy
Just had been wondering for a while how easy it would be to make a terminated adapter, and the answer is very easy
I thought for some more modern drives you needed to terminate some pins of the 80pin connector, so the drive would know that it is being used with ancient things?
That or use a 68pin cable with it's own terminator on the end and hook that to the motherboard and drives with adapters.
That is what I remember hearing anyway.
That or use a 68pin cable with it's own terminator on the end and hook that to the motherboard and drives with adapters.
That is what I remember hearing anyway.
Yes that is correct, some 80pin drives need the extra lines terminated, whereas others don't, so this will only work for ones which don't need them terminated
I do plan to make one that terminates the extra lines on the 80 pin connector, but first i need to find a drive that doesn't work without doing that
I do plan to make one that terminates the extra lines on the 80 pin connector, but first i need to find a drive that doesn't work without doing that
I have a Compaq BD0366459B (36GB 10k RPM) that appears to need termination on the 80pin, or use a 68pin cable.
I can just use it with a 68pin cable but in a cramped space that might not be as nice unless I also used a flexible extension on the mobo side of the the 68 to 50 pin adapter.
*shrug*
I can just use it with a 68pin cable but in a cramped space that might not be as nice unless I also used a flexible extension on the mobo side of the the 68 to 50 pin adapter.
*shrug*
seems i can get one for ~£9 might get one and try terminating the extra lines
Ordered a BD0366459B, hopefully i should have it tuesday
Will see if terminating the extra lines gets it working
Will see if terminating the extra lines gets it working
extra lines terminated, works on my sca drive, hopefully it should help with picky drives, will be seeing next week
initial tests with the BD0366459B seem sucessfull, it is recognized and is currently being formatted.
Once it is formatted I will test it on the adapter without the extra lines terminated and see if it still works
Edit, well, it seems that it gets it recognised where it otherwise wouldn't. However it failed in formatting and is now saying it can't get the required data from the disk...
Once it is formatted I will test it on the adapter without the extra lines terminated and see if it still works
Edit, well, it seems that it gets it recognised where it otherwise wouldn't. However it failed in formatting and is now saying it can't get the required data from the disk...
Wow, a new record! the drive failed after being powered up for 10 min... so much for fully tested.
oh well, hoefully the seller will agree to just send me annother.
However, the test was successfull, the drive was recognized using mk3 of the adapter, where it wasn't with mk2
oh well, hoefully the seller will agree to just send me annother.
However, the test was successfull, the drive was recognized using mk3 of the adapter, where it wasn't with mk2
I like that idea, I've been using cable-end terminators for drives that need them but this is a tidy approach for space-cramped compact and pizzabox machines.
YMMV but I've found that the Savvio drives seem to work fine without any additional termination. I assumed the drives have onboard termination but I could simply be lucky.
YMMV but I've found that the Savvio drives seem to work fine without any additional termination. I assumed the drives have onboard termination but I could simply be lucky.
I picked up a handful of 50-pin inline terminators for $1 each last weekend. I've used them before and they work pretty well in between the adapter board and ribbon or between the ribbon and the logic board if there's room.
Yeah, it is really just the luck of the draw weather a drive requires extra termination. For ones that don't there is no need to add the extra 8 resistors.
Using inline terminators was what i originally intended to to, however i decided just to see if i could just add the termination to the board.
However i guess the real use of these is not so much for the termination, but to allow some more picky drives to be used
Using inline terminators was what i originally intended to to, however i decided just to see if i could just add the termination to the board.
However i guess the real use of these is not so much for the termination, but to allow some more picky drives to be used
Awesome work.
Thanks
I shall be makeing a few of these if any members are interested, £4.50 + whatever the shipping is.
I shall be makeing a few of these if any members are interested, £4.50 + whatever the shipping is.
finally got a working BD0366459B (first was bad, second i think got damaged in transit) i can confirm that terminating the extra lines made all the difference, without doing it the drive is not seen in anything but with it the drive works fine
Great R&D on the wide side termination issue, comrade. :approve:
thanks
Tbh it was less of research and more of just probing a dead hdd to find out how it was terminated, and then a little guesswork
Hopefully this will allow a much wider range of drives to be used in these old macs, i'm planning to buy a random sample of whats on ebay and see which work
Tbh it was less of research and more of just probing a dead hdd to find out how it was terminated, and then a little guesswork
Hopefully this will allow a much wider range of drives to be used in these old macs, i'm planning to buy a random sample of whats on ebay and see which work
That pretty much sums up the definition of R&D to me!
Your right there actually, I guess I can call it R&D then
Also, anyone else have a recommendation of a picky drive I should try next? If not I'll just grab the first sub £10 sca drive my next eBay search brings up (actually I did find a lot of 5 36gb sca's for a little over £20, very tempting...)
Also, anyone else have a recommendation of a picky drive I should try next? If not I'll just grab the first sub £10 sca drive my next eBay search brings up (actually I did find a lot of 5 36gb sca's for a little over £20, very tempting...)
Got a new drive today, and it has a interesting feature, it can be set to narrow or wide mode...
in wide mode it needs the extra lines terminated, but in narrow mode it dosen't
the drive is a 9.1gb 7k2 rpm compaq bb009135b4 (or a fujitsu mah3091mc - it is the same drive) i wonder if this is common on ultra 2 drives?
(i must add i haven't tried it on a 68k yet, just on the g4 qs, but i don't see why it wouldn't work)
in wide mode it needs the extra lines terminated, but in narrow mode it dosen't
the drive is a 9.1gb 7k2 rpm compaq bb009135b4 (or a fujitsu mah3091mc - it is the same drive) i wonder if this is common on ultra 2 drives?
(i must add i haven't tried it on a 68k yet, just on the g4 qs, but i don't see why it wouldn't work)
try it first.
before you say this.
I have to disagree with you, Uni. There's no problem with forming a theory and sharing it. It's not as though he said it worked when he hadn't tested it. Hopefully he will test it and share the results.
We're all here to learn, as well as help, one another; share knowledge, experience, and theory, no?
We're all here to learn, as well as help, one another; share knowledge, experience, and theory, no?