Plus keyboard doesn't work?

[Fred1212]

HI everyone
I have a Plus board that boots and the mouse works but not the keyboard. So far I have -
sounded the tracks from the keyboard socket to the TSG and the SCC(6522) and they are all good
Sounded through a keyboard cable as above
tried 2 known working keyboards
socketed and replaced the TSG and SCC
Anyone suggest what to look at next?
Thanks in advance

 

[Nixontheknight]

make sure the cable isn't a regular phone cable, otherwise you have an expensive keyboard shaped paperweight

 

[Fred1212]

Yes thanks it is the correct cable

 

[falen5]

check the cable connectors - make sure their connecting pads are clean - look into the connecting ports on the mac and the keyboard - make sure the connecting pins are in the correct position and clean as well - easy to damage

 

[dv-]

I had a similar issue with one; turned out the jack on the keyboard was making intermittent contact. Worked when I tested it at the angle that was convenient to my multimeter but, not flat on the desk.

*facepalm*

 

[Durosity]

make sure the cable isn't a regular phone cable, otherwise you have an expensive keyboard shaped paperweight

I’m curious as to what actually happens when a phone cable has been used? I’ve got a keyboard that doesn’t respond at all which I suspect has had this happen to it, but I’ve never really looked into the cause or potential remedies for it.

 

[mmmlinux]

The plus wants a straight through cable. The phone cables are like rollover cables.

 

[LaPorta]

I’m curious as to what actually happens when a phone cable has been used? I’ve got a keyboard that doesn’t respond at all which I suspect has had this happen to it, but I’ve never really looked into the cause or potential remedies for it.

It blows something in the keyboard itself. I forget what it is, but it is covered in the Dead Mac Scrolls.

 

[A24A]

I’m curious as to what actually happens when a phone cable has been used? I’ve got a keyboard that doesn’t respond at all which I suspect has had this happen to it, but I’ve never really looked into the cause or potential remedies for it.

LaPorta mentioned the Dead Mac Scrolls by Larry Pina. On page 97 in my book (1992, ISBN 0-940235-25-0), replacing an 8048 (40-pin DIP, MPU 8-bit) chip located under the spacebar is said to be the solution for a non-working M0110A (Mac Plus) keyboard if a telephone cable has been used.

A telephone cable set (that is, the type with the smaller 4P4C plugs, typically used between the handset and the telephone base) should actually work with a Macintosh Plus, but only if one plug is reversed (cut one plug from the cable, turn a new plug 180°, crimp on). One could of course also use a standard 4-wire phone cable and crimp on both 4P4C plugs (I have done this myself). In any case, double-check pinouts and wiring before connecting anything.

 

[A24A]

LaPorta mentioned the Dead Mac Scrolls by Larry Pina. On page 97 in my book (1992, ISBN 0-940235-25-0),

Should of course read:

LaPorta mentioned the Dead Mac Scrolls by Larry Pina. On page 97 in Pina's book (1992, ISBN 0-940235-25-0),

 

[Fred1212]

Thanks for the replies everyone, unfortunately I'd covered pretty much all the bases and I'm still not sure what is causing it. Put aside for another day!