Whoops, I did it again. I have a problem, Dragon 32 inbound

[stephen_usher]

Oh yeah, they're very different. Probably easier to clean though as the contacts are exposed.

[rubber_jonnie]

Oh yeah, they're very different. Probably easier to clean though as the contacts are exposed.

Indeed, just need to find something nice and fine to 'sand' them with.

[stephen_usher]

Something "soft" such as a cocktail stick should work.

[rubber_jonnie]

Something "soft" such as a cocktail stick should work.

I'm sure I can find something like that.

[rubber_jonnie]

Ok, so I have some definite keyboard improvement after breaking out a new can of Electrolube (I think the previous can was Servisol, it's not as good), and I have managed to get SDCX (The Dragon equivalent of SofaRun for the MSX) to finally run.

It was more by luck than judgement, I mounted the SDCX.VDK file (SDRIVE 1,"SDCX.VDK"), used 'DIR' to confirm it was mounted, and used 'RUN "CONFIG.BAS" and selected all the options on, then hit ENTER to save and was able to actually start SDCX for the first time since getting the cart.

PXL_20220823_092507740.jpg

However, I'm now thinking there might be other problems, specifically RAM, as it keeps crashing and doing odd stuff, so I think the Dragon is going to be back on the bench for dome more work in the near future.

It could also be SD cart wobble, so I'll take a look at the cartridge connector on the machine too.

[rubber_jonnie]

Yep, definitely some problem going on, as you can see from the corruption when navigating the SDCX file browser:

PXL_20220823_102734589.jpg

PXL_20220823_104507341.jpg

So some more investigation required for the Dragon :(

[stephen_usher]

More RCM (Randomly Corrupting Memory) than RAM then. :-)

[rubber_jonnie]

More RCM (Randomly Corrupting Memory) than RAM then. :-)

Indeed it is!

Will have a look at the schematic, see if there are any buffers or multiplexers at play, might not be RAM at all, but definitely not right!

I think possibly a little Electrolube on the sockets too.

[rubber_jonnie]

Well, it was a good day for the Dragon, the new 4164s arrived and I fitted them:

PXL_20220827_151644956.jpg

And now the SDCX browser seems to run stably, and I am able to run all sorts off it now, which is great, though the keyboard is still double typing or not typing at times and for specific keys (I should check what part of the matrix they are all on), but at least the darn thing works now overall.

I have to say though, the Dragon mainboard is super fragile and my desoldering attempts ran into a few problems with lifting pads with very little heat applied.

In the end, the safest way was to snip all the legs on the old RAM and then remove the legs one at a time. Really not my favourite way of doing things, but it was that or damaging the PCB.

It was hard even with my desoldering gun.

Just be aware if you have a Dragon of your own and need to get soldering.

[stephen_usher]

:dualthumbup: