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Re: Egyptian Enterprise 64 number 2
Posted: 22 Oct 2026 09:33
by rubber_jonnie
OK, so the L2 mod simply provides a stable 14Mhz clock to Nick as it would seem the circuit that generates it gets unstable over the years.
Could I simply use one of the clock outputs on one of my clock boards to replace this?
More thinking required :)
Re: Egyptian Enterprise 64 number 2
Posted: 22 Oct 2026 11:35
by alexh
I haven't been able to get a login on that forum so I can't see the pictures or download the schematics/diagrams in the thread I referenced for "The L2" fix.
Re: Egyptian Enterprise 64 number 2
Posted: 22 Oct 2026 12:09
by rubber_jonnie
alexh wrote: 22 Oct 2026 11:35
I haven't been able to get a login on that forum so I can't see the pictures or download the schematics/diagrams in the thread I referenced for "The L2" fix.
So here's the thing, I've been able to get on and frankly there isn't much to see.
Essentially the OP stated that whilst adjusting L2 on their machine the core broke and a replacement adjustable inductor couldn't be found.
Basically he removed this part of the circuit entirely from his machine as it wasn't working:

- Screenshot 2026-10-22 at 12.04.30.png (426 KiB) Viewed 24 times
And replaced it with an oscillator that generates the 14Mhz clock that goes to Nick. I could do that with my clock replacement board, however I may consider seeing if L2 on this machine can be adjusted with the correct tool and that may be enough to change the shimmer.
Re: Egyptian Enterprise 64 number 2
Posted: 22 Oct 2026 12:14
by PhilC
If it ain't broke, don't fix it, messing with that may cause the whole thing to misfunction.
Re: Egyptian Enterprise 64 number 2
Posted: 22 Oct 2026 12:21
by rubber_jonnie
So case repairs done this morning :)
I started off by melting some staples across the cracks to help stabilise:

- PXL_20261022_100939881.jpg (242.62 KiB) Viewed 18 times
Then I added GRP strips and UV hardening resin to add strength:

- PXL_20261022_104503626.jpg (271.56 KiB) Viewed 18 times
I didn't add staples to the other machine since the case was just cracked, however since the case for this one was actually in 2 parts I felt the staples would give a bit more strength to the repair. They were just melted in with the soldering iron.
The case looks good now :)

- PXL_20261022_104906864.jpg (317.32 KiB) Viewed 18 times
Yes, there are visible cracks on the outside, but unless I was filling them, sanding and painting the whole case they will always be there. For me thats the patina of age and I'm good with it.
My replacement keyboard membrane is in the post, so I need to do a few things with the mainboard, like look at the L2 thing and try out RGB 2 HDMI before I get round to reassembling.
Next up though the CPU is getting socketed so I can figure out wether or not the RAM IC is bad or the CPU.
Re: Egyptian Enterprise 64 number 2
Posted: 22 Oct 2026 12:29
by stephen_usher
That 14MHz clock circuit is very voltage sensitive. Undervolt it on the +12V and becomes very unstable.
Re: Egyptian Enterprise 64 number 2
Posted: 22 Oct 2026 12:57
by PhilC
Nice idea with the staples, been meaning to try something similar for a while bow
Re: Egyptian Enterprise 64 number 2
Posted: 22 Oct 2026 13:21
by rubber_jonnie
PhilC wrote: 22 Oct 2026 12:14
If it ain't broke, don't fix it, messing with that may cause the whole thing to misfunction.
Yeah, starting to get bad vibes about messing with it TBH, it's been through so much and just works.
Re: Egyptian Enterprise 64 number 2
Posted: 22 Oct 2026 13:22
by rubber_jonnie
stephen_usher wrote: 22 Oct 2026 12:29
That 14MHz clock circuit is very voltage sensitive. Undervolt it on the +12V and becomes very unstable.
Noted thanks.