IBM 5150 + Tecmar expansion chassis help

[bsonej]

HI all.. new to the board

Got a question for someone in the know.

I have an old 5150 and a Tecmar expansion chassis with a tecmar controller and a ST506 seagate in it. Some time ago, the two ribbon cables (50 pin) going between the two expansion cards in the PC and Tecmar respectively were disconnected at the tecmar end. I do not know how these cables are supposed be connected as they are both 50 pin scsi. The boards are not marked and the cables can go in any combination 1/2 up/down etc. No way to know where pin one is on each card

Anyone have any info on these or know if the cables were installed incorrectly would it destroy the adapters?

Thanks!
brian

 

[per]

HI all.. new to the board

Got a question for someone in the know.

I have an old 5150 and a Tecmar expansion chassis with a tecmar controller and a ST506 seagate in it. Some time ago, the two ribbon cables (50 pin) going between the two expansion cards in the PC and Tecmar respectively were disconnected at the tecmar end. I do not know how these cables are supposed be connected as they are both 50 pin scsi. The boards are not marked and the cables can go in any combination 1/2 up/down etc. No way to know where pin one is on each card

Anyone have any info on these or know if the cables were installed incorrectly would it destroy the adapters?

Thanks!
brian

If you open the chassises and look at the cards, pin 1 is usually marked in some way. Usually by a small arrow or a "1" number, sometimes just a squared soldering pad (if the rest are circular).

Pin 1 on the cable should match pin 1 on the card. Pin 1 on the cable is usually marked with one of the wires colored in another color or pattern, or by a small arrow on the connector itself.

Anyways, pictures would be great.

 

[bsonej]

You're right, yes, normally there's a way to determine pin 1.... but in this case there's nothing obvious (to me anyway)..

Here's a photo:

Is there anything obvious there that should be a hint to me?

 

[per]

You're right, yes, normally there's a way to determine pin 1.... but in this case there's nothing obvious (to me anyway)..

Here's a photo:


Is there anything obvious there that should be a hint to me?[/QUOTE]

Can you photograph the back of it too?

An overview photo of both the expansion box and the IBM would also be great.

 

[bsonej]

Here you go, no markings on the back either.

Here's the overall:

 

[per]

Here you go, no markings on the back either.

Here's the overall:
[/QUOTE]

Note that several of the pins are grounded. As different pins are grounded on the two connectors, I don't really think it is SCSI. I may be wrong, as I don't really know the pinout for SCSI.

If you look at both cards, try to match the connectors with the same grounded contacts. How the connectors are plugged doesn't really matter as long as they are plugged in the same way on both cards (in terms of what contacts that's grounded).

 

[bsonej]

OK.. i'll look at it that way.. I didn't really say it *was* SCSI.. just a way to describe the ribbon cables easily I guess

So hopefully that will give me what I need to get pin 1 sorted.. still need to figure out which pin bank is 'send' and 'recieve' on the respective cards

Thanks for the responses!

 

[per]

OK.. i'll look at it that way.. I didn't really say it *was* SCSI.. just a way to describe the ribbon cables easily I guess

So hopefully that will give me what I need to get pin 1 sorted.. still need to figure out which pin bank is 'send' and 'recieve' on the respective cards

Thanks for the responses!

As long as you got the connector the same way on both ends, it doesn't really matter where pin 1 is. The only thing you should make sure is that grounded pins goes to grounded pins and not to something else.

 

[Chuck(G)]

Look at the connector with all of the odd (or even, depending on how you look at it). The corresponding connector in the expansion box with have the same configuration; i.e., all of the odd or even pins grounded. Hook up your first cable between the two so that the grounded pins connect. Hook up the other cable in exactly the same orientation. Which pin is actually pin 1 doesn't matter, as long as the cable hooks the right pins together (e.g. you can install a 40-conductor IDE cable "backwards" as long as it's backward on both ends).

 

[bsonej]

I got the pin 1 thing sorted I think.. it's the which cable goes where that's still up in the air. No way of knowing that part yet

 

[per]

I got the pin 1 thing sorted I think.. it's the which cable goes where that's still up in the air. No way of knowing that part yet

once again, look at the contacts that are grounded.

One of the connectors has all the contacts on one side grounded, while the other one only has some grounded. For the one with all on one side grounded, it should match the connector on the other card with half of the contacts grounded.