General Stuff(tm)

[stephen_usher]

Thanks!

I'm re-doing my PCB from scratch as the first one needs far too many changes, most of which are under the 15 pin male socket.

[stephen_usher]

The Mk.II design is now with PCBWay.

I'm using an IDC cable with the DB15 on it to a 16 way header on the PCB.

I'm also using a set of pin headers to be able to do the monitor type selection and to switch the input to the LMH1980 between composite sync and the green input. All the signals are also passed across from the Mac side to the VGA, so it the LMH1980 isn't powered then it's a passive straight through connector.

With the input being on an IDC cable it means that if the pinout is incorrect I can always shift the wires around to get them right.

[rubber_jonnie]

The Mk.II design is now with PCBWay.

I'm using an IDC cable with the DB15 on it to a 16 way header on the PCB.

I'm also using a set of pin headers to be able to do the monitor type selection and to switch the input to the LMH1980 between composite sync and the green input. All the signals are also passed across from the Mac side to the VGA, so it the LMH1980 isn't powered then it's a passive straight through connector.

With the input being on an IDC cable it means that if the pinout is incorrect I can always shift the wires around to get them right.

Sounds like my problem with the FreHD exactly, I need something that lets me account for the weird edge connector layout.

[PhilC]

Sounds like a plan @stephen_usher

[stephen_usher]

The new Mac video sync splitter PCBs have arrived, but I won't have to time look at anything until late Sunday at the earliest as I'm going down to Cornwall by train tomorrow to bring my Dad's car back.

I made a mistake on the header, so I'm going to have to manually interleave the wires in the IDC connector as I think the DB15 IDC connector is wired 1,9,2,10,3,11 etc. when viewed from the DB15 pin side, but I will have to check.

Anyway, obligatory picture.

IMG_3438.jpg (252.78 KiB) Viewed 150 times

[rubber_jonnie]

The new Mac video sync splitter PCBs have arrived, but I won't have to time look at anything until late Sunday at the earliest as I'm going down to Cornwall by train tomorrow to bring my Dad's car back.

I made a mistake on the header, so I'm going to have to manually interleave the wires in the IDC connector as I think the DB15 IDC connector is wired 1,9,2,10,3,11 etc. when viewed from the DB15 pin side, but I will have to check.

Anyway, obligatory picture.



IMG_3438.jpg

Be good to see the results, hope the trip to Cornwall goes well.

[stephen_usher]

Thanks.

At least this time the DB15 isn't hard wired so it's more flexible

[stephen_usher]

Home again after driving my Dad's (was mine originally) car back from Cornwall.

IMG_3440.jpeg (386.38 KiB) Viewed 125 times

Managed to get 39 mpg, about the same as when it was new. Not bad for a 23 year old car with 113K miles on the clock.

A few things to get done on it before it can be my retro-computing transport vehicle. (It has a cavernous hatchback, unlike the boot of the BMW.)

Anyway, trying to see if I have enough energy to do the Mac VGA adapters this evening. Not sure if I will.

[stephen_usher]

Made up one of the new boards and the cable... with manual interleaving of the 9->15 wires in between 1->8 due to my stupidity with the header pin numbering. (That was hellish to do.)

IMG_3441.jpeg (418.21 KiB) Viewed 101 times

Checked, checked again with multimeter and everything seemed to be fine.

Tried it, and the Mac saw no display connected. Couldn't work out what was wrong... Until I took yet another look at the pin out diagram. The pin numbering was the opposite way around to that written on the IDC DB15 plug! The wires were the wrong way around!!!

I can't fix this by flipping the cable at the header end, oh no. I'll have to re-wire at the D-B-15 end!!! Arrrgh!

OK. I'll make another cable tomorrow. I've given up for tonight.

P.S. those resistors are there as I don't have any 100 ohm surface mount ones so those 120R through hole ones will have to do.

[rubber_jonnie]

Made up one of the new boards and the cable... with manual interleaving of the 9->15 wires in between 1->8 due to my stupidity with the header pin numbering. (That was hellish to do.)


IMG_3441.jpeg


Checked, checked again with multimeter and everything seemed to be fine.

Tried it, and the Mac saw no display connected. Couldn't work out what was wrong... Until I took yet another look at the pin out diagram. The pin numbering was the opposite way around to that written on the IDC DB15 plug! The wires were the wrong way around!!!

I can't fix this by flipping the cable at the header end, oh no. I'll have to re-wire at the D-B-15 end!!! Arrrgh!

OK. I'll make another cable tomorrow. I've given up for tonight.

P.S. those resistors are there as I don't have any 100 ohm surface mount ones so those 120R through hole ones will have to do.

After my escapades with the M1 hard drive adapter and FreHD, I feel your pain.