x68000 XVI PSU question and others.

[vanpeebles]

Morning, I got a spares repairs XVI which I'm hoping just needs the ATX PSU treatment. For the floppy leads 3 pin, 12v, 5v, GND, do ppl solder both GNDs from the molex to the single GND on the floppy cable? I've seen cables just using a single GND, with the other cut from the molex.

Also is the 16mhz switch used when turned on or off?

Cheers! 

[leonk]

Think of electric lines like water pipes.  The reason there are 2 ground wires is because there's a heck of a lot more power wires .. you want to make sure the electrons are able to flow back and not be constrained.  You can use 1 return GND wire, but it has to be sufficiently big to support the 5V and 12V lines.

[vanpeebles]

Would you solder the two molex ones together or just use a single. I'm thinking I'll probably join them just for neatness.

[caius]

Would you solder the two molex ones together or just use a single. I'm thinking I'll probably join them just for neatness.

It doesnt matter, it's the same.GND is common among the two molex headers 

[vanpeebles]

Ah I might just cut one out then and save on the soldering. The wires on the x68000 don't seem as thick as the ATX ones.

[vanpeebles]

Ok, I've made up a loom, it's a lot rough in places, and needs tidying up then testing first. Does it look right?

http://www.zen70509.zen.co.uk/x/power/

[vanpeebles]

Does anyone know what crimp connector on the x68000 part of the motherpower cable is? I noticed one of mine didn't quite look right, when I removed it, the prong bit dropped off the end. It's like a box shape with an S prong on the end.

[vanpeebles]

Well I've connected it all up, power on and all I get is timer light on red, and the 10mhz light on green. Any ideas?

[vanpeebles]

Well I've made some progress on this! It now powers up, plays a game with sound. No picture yet though, I need to go back and check my work on the rgb module. Still it feels like a victory, as it was completely dead!

[Nicky Biscuit]

Great to hear you're making progress.

I've just recapped the power supply on my Compact, need to reinstall and see what happens, hopefully it doesn't go bang and the sound comes back!

[vanpeebles]

Cheers! Fingers crossed for you! 

[vanpeebles]

Still no luck with the RGB module. I redid one cap that I thought wasn't quite right, but everything else checks out ok. I've ordered some SN74ALS05AN chips to replace the one on the mobo. Reading around here etc, a few people have had no screen output and fixed it by replacing that. Fingers crossed again

[emerald danjon]

I hope you can fix the Video problem replacing this SN74ALS05AN,
every time i read this things about X68000 Computers suddenly dont work for no reason"apparently"i feel FEAR.

[vanpeebles]

Gah, one step forward and two back. Replaced the chip, checked the pins against the service manual online and checked on the little take off points. Plugged it all in, and the ATX PSU just automatically makes a high pitched whine, and the fan doesn't turn. I wonder if I disturbed the wiring on my small PSU inverter board thingy. I was sure the chip was all ok too.   

[hoshikawa]

take a multimeter and check continuity of the main board 5vdc in to ground. when I reassembled my XVI it made a high pitch squeal, turned out the 5 volt rail was shorted to the rf shield. my solution was to put a bit a paper board from a cereal box between the backside of the board and the shield.

[vanpeebles]

That sounds like excellent advice, many thanks. I'll check that and report back! *fingers crossed*

[vanpeebles]

YES get in! Badly fitted RF shield it was! Many thanks!

I have a picture now, and it's playing Alien Syndrome nicely! So to sum up, new caps on mobo and rgb, new hex chip, atx psu, and taking time to fit the rf shield properly and making sure it all lines up.

[hoshikawa]

Glad I could be helpful, I was scratching my head as well until I broke out the fluke.

[Nicky Biscuit]

Congrats on getting it working! Another returned from the dead!

[vanpeebles]

Next step is to get all the wires tidied up and try out the scsi2sd. Thanks again, made my day when it worked! I'm still not entirely sure where it was shorting out. I think I didn't have the lower half of the motherboard RF clipped into the sliding clips, so the top flexible shield was a bit wonky.

On a side note, what screen dshould the XVI power on with and how does the CPU speed switch work? My Pro II boots up with the white insert disk logo box.

[samaron]

Not sure how it is without a hard drive, I've never used my XVI without one. With a hard drive it is just a black screen and when drivers and whatnot start to load you get text on the screen (like MS-DOS).

When switching between 10 and 16 MHz I've always soft-powered off the computer before switching. The power LED changes to what speed I select. Not sure what happens if you try to switch while it is powered on.

[vanpeebles]

I'm just getting a black screen too. I've noticed the CPU switch only works when powered off.

[hoshikawa]

if the boot setting is set to standard it will eventually prompt for a floppy after probing the SCSI bus. The CPU select switch can be toggled while the machine is running but will have no effect until a reset.

[vanpeebles]

Ah that explains it. My next step is try out the scsi2sd, and hopefully that should be it!

[vanpeebles]

Just thought I'd put up a few piccies of my power setup on my normal XVI (not compact), hopefully help others with ideas of what to do (or not! )

[hyrulebr]

Just thought I'd put up a few piccies of my power setup on my normal XVI (not compact), hopefully help others with ideas of what to do (or not! )

Are you using a Expert floppy drives in a XVI? All (tower models) drives are exchangeable?

[vanpeebles]

I've no idea, that writing was already on I thought it meant a hard drive from something else. The drives have two little cables and one main one. Different from the ones in the Pro II desktop I have.