exxos's Atari, Amiga & retro forum

Hi All,

Just wondering if anybody else has experienced issues with using midex or unitor on cartridge ports on different STs. I have issues where sometimes they are recognised and not. I think maybe the cartridges are extremely sensitive to the angle of insertion (oo er).

Has anybody taken the edge connector from the st and instead put it at the end of a cable to remove the finnicky need to line up correctly. I'm considering trying this.

I have an stfm with 4mb and a mega st4 and both seem to have similar afflications - probably because of my cramped desk which isnt quite level, and isnt exactly flush with space! (I think there are about 15 antique computers along with the yamaha recorder, and a coupe of synths and a sampler!

Thank in advance

Rich

You should probably start by making sure your PSU is recapped. Also bus resistors I recommend changing. You can pretty much put your finger on the cartridge port and it will prevent your machine from booting!

Have a look here...

https://www.exxosforum.co.uk/forum/viewt ... =17&t=1585

I've been plugging/unplugging my diag cart a lot lately, and it's variable if it works or not.

Usually I clean the edge connections and things are fine, but power is a big consideration. If the PSU can't deliver, the whole machine may not boot. A refurbished PSU will certainly help.

I've also seen variations that cause shorts if the cart is too much to the left or right, so a wiggle often helps.

Thanks guys - glad it's not just me! I think the midex in particular the shape of the expansion is less than helpful.... at least there's no wiggle room though.

@exxos You have just had my order for bits to recon the megast4 psu. Looks like i need to look at bus resistors too. Thanks! Appreciate this wealth of knowledge that's posted around the site! I'm not exclusively an atari guy so i dont have a lot of this specialist knowledge. I used to have an st running cubase and amiga 1200 synced running octamed. I found pc cubase very stale to use, possibly just needed change i think, so i've foregone the internal sampler of my fa06, and my soft synths to go back to atari.

The stfm i just changed the 2.2s and that restored it's stability. I intend to use the fm as a games machine and the mega for cubase exclusively so it's the mega i want to put the effort into..

Thanks for the responses :)

Rich

@rubber_jonnie Thanks - yes i've used medical alcohol to clean both the 'cartridges' and the edge connector on the computers. This does help as you say.

Whilst i can get the unitor to behave that way, the midex seems to be too much for it. It does work sometimes, but i wouldnt dare write a song with it as it stands.

richard.faulkner wrote: 28 Apr 2020 14:26 @rubber_jonnie Thanks - yes i've used medical alcohol to clean both the 'cartridges' and the edge connector on the computers. This does help as you say.

Whilst i can get the unitor to behave that way, the midex seems to be too much for it. It does work sometimes, but i wouldnt dare write a song with it as it stands.

Definitely sort the PSU out. I went for a Meanwell in my Mega 4, seems to have done the trick, but my Mega 1 has a PSU that hasn't been 'done' yet, and also has a Megabus IDE adapter and a laptop 2.5" HDD. It won't boot with the diag cart plugged in, it's just too much.

THanks

Well the good news is that the bits to recon the psu for the mega st4 arrived yesterday. I've done most of it, just 2 resistors to go then we get to the moment of truth!

richard.faulkner wrote: 30 Apr 2020 13:37 Well the good news is that the bits to recon the psu for the mega st4 arrived yesterday. I've done most of it, just 2 resistors to go then we get to the moment of truth!

Were expecting a full report, and no magic smoke!

Really hoping for no smoke :D