Page 1 of 1

Unused GSTMCU wire (STe) and HD7.0

Posted: 05 Nov 2024 23:30
by Pacman
Having had my STe in storage I've forgotten a few things such as loose wires along with a bunch of add-ons and modifications.

I noticed a loose wire soldered to the motherboard underneath the power supply and located the connection being to pin 2 (CLK) of U400 (GST MCU chip). If I'm not mistaken this is a 16 MHz clock signal as shown here (scroll down to the right-hand side photo entitled "Fitting to STe").
I did put an Exxos HD version 6 into my STe, but think I messed it up and therefore bought an Exxos HD version 7.0 to replace it (which is now clearly visible in my STe).

So..... I think the loose "CLK" wire is just a left-over from the version 6 board, and no longer needed with the version 7, as it has a built-in 16 MHz oscillator which takes care of that, right?
I can't think of anything else the wire has been used for... or can be used for later. Any thoughts on this? Should I just leave it for other uses, or might it only cause potential interference problems if it gets close to other cables or parts of the motherboard?

Re: Unused GSTMCU wire (STe) and HD7.0

Posted: 07 Nov 2024 12:32
by Badwolf
Pacman wrote: 05 Nov 2024 23:30 So..... I think the loose "CLK" wire is just a left-over from the version 6 board, and no longer needed with the version 7, as it has a built-in 16 MHz oscillator which takes care of that, right?
I can't think of anything else the wire has been used for... or can be used for later. Any thoughts on this? Should I just leave it for other uses, or might it only cause potential interference problems if it gets close to other cables or parts of the motherboard?
If it's not connected anywhere and you're happy with your machine working, I'd remove it.

You've got an unterminated 16MHz antenna there. It's unlikely to be a good thing.

BW

Re: Unused GSTMCU wire (STe) and HD7.0

Posted: 07 Nov 2024 14:45
by Pacman
Badwolf wrote: 07 Nov 2024 12:32 If it's not connected anywhere and you're happy with your machine working, I'd remove it.

You've got an unterminated 16MHz antenna there. It's unlikely to be a good thing.
Good point! And probably applicable for any loose wires left dangling.

My Exxos HD/DD floppy drive module (7.0) appears to have all its wires connected. The 3 external wires attached are P1, P2 and D0.
D1 isn't used.
20241107-153332_PB070002.jpg
I can't locate any pin marked with something resembling a 16MHz input, so is it safe to assume everything is connected as it's supposed to and I can remove the unterminated 16MHz "antenna" wire?
(unfortunately the STe isn't ready for use at the moment, or else I'd just try it out and see).

Re: Unused GSTMCU wire (STe) and HD7.0

Posted: 07 Nov 2024 15:00
by Darklord
Here's the 3 wires coming off of my Exxos HD mod installation. You can see
where the wires go. The far left one goes to the floppy drive mech. itself:

(older picture - I touched it up a bit after this)


20240811_162954.jpg

Re: Unused GSTMCU wire (STe) and HD7.0

Posted: 07 Nov 2024 15:24
by Pacman
Thanks.
It appears to be the same as with mine except the two thick wires (red and white) don't go to U8 (Yamaha YM-2149) but rather to the two connection points of W301 (as shown in the Exxos installation page's photo for HD module version 6).
The third wire goes to the floppy drive (to the HD select switch as far as I remember. It's been a while since I opened up the drive).

So.... it appears I have no need to the 16MHz wire (I can't think of any other modification or add-on which needs it either) and can safely remove it.