exxos's Atari, Amiga & retro forum

Hey guys,

Can anyone help me out with this? I'd like a rather short old-style internal ribbon SCSI cable, 50 pin. Just two connectors (for one device) When I look on ebay they're all in the USA, so if anyone can help me out here it'd be great.

Cheers
Steve

What sort of connector? There's a large Centronics type, a micro-D and the good old IDC connector type, which you can easily make yourself.

The best thing about standards is that there are so many to choose from.

I took internal to mean 50pin IDC to 50pin IDC.

Can't help, though, sorry.

BW

In which case, @Steve what length do you need? I've some IDC (male) connectors and 50 way ribbon cable I was using for my Macintosh Portable memory board. I think I've enough connector to make another cable, not that they're hard to come by.

@stephen_usher Yes this is for my TT. I only have quite long cables and I noticed the TT doesn't work properly if I put devices on the end of the cable, then when moving the device to the first (middle) connector it worked much better, but still not perfect.

Something around 30cm would be great.

I think I may have had some of this somewhere. Will try to fish some out if Stephen can't help.

As for the length issue...

I'm sure I read back in the day SCSI cable could be quite long without having any issues, certainly longer than the internal length ribbons. (Perhaps that was the thick well shielded external cables though).

Still, it sounds like you have another problem there. What have you got plugged in (on the whole SCSI chain)?

It sounds as if your SCSI bus isn’t terminated.

Either the drive should have terminating resistors fitted or you have a terminator on the end of the cable.

stephen_usher wrote: 17 Nov 2021 23:57 It sounds as if your SCSI bus isn’t terminated.

Either the drive should have terminating resistors fitted or you have a terminator on the end of the cable.

Yep, giving signal bounce. Or maybe a non powered terminator when it needs powered?

stephen_usher wrote: 17 Nov 2021 23:57 It sounds as if your SCSI bus isn’t terminated.

Either the drive should have terminating resistors fitted or you have a terminator on the end of the cable.

Yep, I agree, that is what I thought too. Do you have pictures of the drive PCB? Is there an empty termination socket, or does it have a jumper?

The two devices I have are SCSI2SDv6 and a RaSCSI. I have had term resistors inside the TT installed at all times (nothing on external bus) just testing one device at a time. Oddly the SCSI2SD worked more reliably with termination disabled. I've only tried RaSCSI with termination enabled so far. Problems experienced: with a long SCSI cable, basic write and read operations lock up, with a short cable TOS copy operations seem fine (copied 2800 from IDE drive to SCSI) BUT Kobald *always* fails, it reads the files into memory and then starts to perform its write operations on SCSI, it starts 'updating fat tables' before the file copy, the drive locks and then a few minutes later Kobold returns a 'drive not responsive' error.

Hope that all makes sense. I also tested an external CD-ROM on my TT and that would only read discs, but would fail on write in Extendos. My TT must have some kind of problem.

Would the first place to look is perhaps check the internal resistors are working properly? I bet this could be a real rabbit hole of diagnostics for me :O