exxos's Atari, Amiga & retro forum

stephen_usher wrote: 17 Mar 2022 11:01 Oh, very strange!

Good luck! :-)

Thanks, I may need some :)

Ok, so in the 600XL, I'm getting stereo out again, but bypassing the A4 passthru line that goes via the U1MB to the PokeyMax and connecting direct to PokeyMax. Lines are directly connected to the desktop speakers, so next I need to feed them through the SCART cable.

Ah, the fun of getting multiple community created expansions to work together.

stephen_usher wrote: 17 Mar 2022 14:42 Ah, the fun of getting multiple community created expansions to work together.

You forgot to say 'Again'!!

Getting stereo thru the SCART again with the A4 line direct to the PokeyMax. All really kind of peculiar, need to go back to the U1MB wiring diagram I think.

Still doesn't explain the weirdness with the 65XE, but we'll get to that in time....

Ok, so the PokeyMax saga is done. Both are installed, one in the 65XE and one in the 600XL and both now work flawlessly.

I don't entirely know what happened, but I'm not going to complain. The 800XL and 65XE are both reassembled, but both have a minor snag to resolve. The 800XL has a non-functional power LED and the 65XE has a non-functional reset button.

Neither of these things are terrible, and both are most likely the result of problems with the keyboard ribbon. They have different keyboard setups, with the 800XL having a mechanical kbd and the 65XE having a mylar style.

Next on the agenda is the video out on the 600XL though, now coming from the VBXL. The picture is bright and colourful, but I'm seeing shimmering, almost like a wave vertically on the screen, and very noticeable.

Since it didn't do that when fitted to the 800XL I'm at a bit of a loss to understand why it might be doing this. Will have to get a video of it.

The horizontal wavy thing,.. Could it be a power supply issue, being too weedy for all the additions?

I know that I had thins with other machines such as my original Spectrum PSU when I had the Interface 1 and Microdrives running. The PSU was underpowered.

stephen_usher wrote: 20 Mar 2022 19:02 The horizontal wavy thing,.. Could it be a power supply issue, being too weedy for all the additions?

I know that I had thins with other machines such as my original Spectrum PSU when I had the Interface 1 and Microdrives running. The PSU was underpowered.

I have considered the PSU, but it is a new PSU from Lotharek and did drive the 800XL fine with the same mods, and I do have 2 of these PSUs and it does the same with both.

However, I am wondering if it is due to noise from the more modern SMPSU as the power socket is awfully close to the video socket (More so than the 800XL) and original video out circuit. And of course the overall layout on the 800XL is quite a bit different to the 600XL.

I do have an old linear PSU from the 65XE so I may just give it a go and see if it makes any difference.

Well, some time has passed and unfortunately I had to rip out all the lovely stuff I put into my 600XL (U1MB, VBXL, PokeyMax) because I was having quite a few issues with the RAM side of things, and I couldn't set U1MB to more than 256KB.

I moved it all back to the 800XL and it all works fine there.

Still keen to upgrade the 600XL I did mod it for 64KB, but it was still a bit flaky, so I have just had this arrive:


It'll upgrade me to 320KB without too much fuss :)

So, relatively quick job, just 2 wires as per the instructions over at Retrolemon and Lothareks site:


One (EXT_SEL) simply goes to pin 9 of the nearby 74LS08 (Red wire) and the other, black wire, goes to pin 16 of the MMU. On this occasion I picked it off at a via at the back near the cartridge port. Thats for CAS_INHIBIT.

It all fits very neatly:


And the RAM tests fine:

So I have it set as default, 320KB, so I need to reassemble and do some pointed testing :)

Gotta be careful though the damn keyboard ribbon is well past it's sell by date and I've already repaired it once today.

Well, it's happily running 320KB demos such as Numen, so all appears to be good :)

Screws are back in now :)