OPD - Long overdue service and keyboard fix

[rubber_jonnie]

@stephen_usher

So here's the culprit:

PXL_20220425_103525286.jpg

Pretty sure I have a replacement to hand.

Construction is reminiscent of the Mac Classic, with the power board up on a metal plate on the LHS and the main display board flat at the bottom:

PXL_20220425_103601061.jpg

Overall no signs of bulging on the caps or leakage, but the damn thing is COVERED in that black grime.

I'll do my best to clean it out before reassembly. I'll also put the 'floating' screw back where it belongs and properly screwed in!!

All the parts thus far are marked as ICL, so whilst I don't doubt that it is based on a Microvitec Cub, it looks like it is fully ICL branded.

[rubber_jonnie]

Got some stuff done over lunchtime.

Here's the old cap removed, was definitely a RIFA!

PXL_20220425_114857261.jpg

PXL_20220425_114838129.jpg

It let go some stuff on the PCB:

PXL_20220425_114955693.jpg

New non-RIFA installed:

PXL_20220425_115606369.jpg

And I also found the 'hot end'!!!

PXL_20220425_115101632.jpg

Next bit before reassembly will be to bow out as much muck as I can and try to get the interior somewhat cleaner. I hate that black coating you get inside CRTs.


Clearly this bit gets quite toasty, the white top of the board is quite brown too, will just have to hope it holds out for the limited use it'll see going forward.

[rubber_jonnie]

@stephen_usher Evidence is in, neck board and main PCB are marked Microvitec.


Neck board:

PXL_20220425_122739596.jpg

Main PCB:

PXL_20220425_122749277.jpg

So I'm guessing that chances are, as you suggest, it's a modified CUB.

[rubber_jonnie]

I noticed this after I'd reassembled:

PXL_20220425_153907331.jpg

There are blanked off holes for controls, not to mention a DIN socket and probably a D-SUB 9 pin connector showing its heritage. The controls are all present, but they are attached to the mainboard and pre-set for OPD use, though there is a brightness control on the front.

I think fitting a 9 pin D-SUB, or at least making an adapter for the 15 pin plug, would be trivial and would hopefully allow it to be used an an RGB monitor, provided of course it doesn't have any weird setup.

[stephen_usher]

Microvitec do/did a lot of OEM customised monitors.

I have an Acorn badged VGA monitor made by Microvitec. There's a Sinclair badged CUB in black too.

This one probably just has a modified PSU plus converter board for the slightly strange RGB output from the OPD. You can use a normal TTL RGB monitor with the OPD with the correct cable adapter. It needs a small amount of circuitry to convert it for some reason.

[rubber_jonnie]

Microvitec do/did a lot of OEM customised monitors.

I have an Acorn badged VGA monitor made by Microvitec. There's a Sinclair badged CUB in black too.

This one probably just has a modified PSU plus converter board for the slightly strange RGB output from the OPD. You can use a normal TTL RGB monitor with the OPD with the correct cable adapter. It needs a small amount of circuitry to convert it for some reason.

I'll have to look at it a bit deeper, would be nice if I could use it as an RGB display for other stuff. I recall seeing pics for the all black cub, wasn't that for the QL? Not forgetting the OPD is kind of a QL :)

[stephen_usher]

Yes, the black CUB was for the QL. I think it was modified so that you could see the extra width of the display in "Monitor" mode.

[rubber_jonnie]

Yes, the black CUB was for the QL. I think it was modified so that you could see the extra width of the display in "Monitor" mode.

Yes, that would make sense.

[rubber_jonnie]

So, with the PSU fixed and the display cleaned inside and out as best I could, I turned my attention to the keyboard.

Removing the many screws holding the PCB to the keyboard mechanism, I lifted the PCB off to find this:

PXL_20220426_091319545.jpg

So there are individual rubber dome switches, nothing like I've seen before. Annoyingly the domes don't come out, so I think I'll have to remove one to see if I can get any contact cleaner inside, unless of course there is a way to pop them apart in situ.

[rubber_jonnie]

This is one of the switches. It has a solid body and the dome is, I think, ultrasonically welded in place :(

PXL_20220426_094809128.jpg

There seem to be some spots, like the 4 dots around the dome and where the leads go in, but I'll have to do some experimentation. Maybe see if I can replace them all with large tac switches if I can find anything as low profile if contact cleaner doesn't work.