exxos's Atari, Amiga & retro forum

Well turns out my other PSU doesn't have - 5v either 🤬

But I did win the Colecovison controller I was bidding on eBay 😁

You need an AT power supply not one of those new fangled ATX jobbies. :-)

stephen_usher wrote: 29 Sep 2024 18:15 You need an AT power supply not one of those new fangled ATX jobbies. :-)

It would seem to be the case, yes, no -5v on those ATX PSUs, both missing that line entirely and I simply don't have an AT supply that I can access easily. I suspect I'd get more traction with a 20 pin ATX, they seem to retain the -5v.

In addition, the Meanwell RPT-60A that I used for my A5000 seems to have shot up in price ridiculously enough that I don't want to buy one, and that has everything I need, but it would mean completely disassembling the A5000...

I did have a thought though, the BBC B PSU runs at 5v and -5v, and I could use one of those with a bench PSU at 12v to get what I need and I can get at a BBC B easier than the A5000. Hmm, what can I do until my ColUSB arrives.

Well, both the Coleco Joystick and the PSU have both shipped :)

In the meantime I have some galvanising paint due tomorrow so I can get the RF shield cleaned up and looking nice again.

I think I also need to look for a suitable AT PSU that will let me have a basic bench PSU for when I need weird voltages like -5v. Time for a scout round eBay...

Just had a facepalm moment. I have a spare Electron PSU that delivers 5v, -5v and if I combine that with a bench PSU at 12v I'll have all of the voltages I need.

:dizzy:

Nice, your project is progressing step by step...

Hmm, reminds me of NKOTB.

:lol:

https://www.youtube.com/watch?guid=ON&g ... pp=desktop

HigashiJun wrote: 30 Sep 2024 10:40 Nice, your project is progressing step by step...

Hmm, reminds me of NKOTB.

:lol:

https://www.youtube.com/watch?guid=ON&g ... pp=desktop

Indeed it is :)

NKOTB seems like a very long time ago to me!!

But I have proof of life:


So it's mostly working. The weird on screen stuff could be that the voltages are not quite up to snuff so I do still need the proper PSU that's ordered. Of course it's 4116 RAM so there may be issues with that too.

Happy with what I'm seeing so far though.

Ah, such a nostalgic screen !

And the proof of life is evident.

A here comes a new machine in your personal museum

:D

HigashiJun wrote: 30 Sep 2024 11:15 Ah, such a nostalgic screen !

And the proof of life is evident.

A here comes a new machine in your personal museum

:D

Indeed it does :)

It looks like both cartridges work as well :)

However, I left it running for a while and gave it the once over with my thermal camera. Aside from the CPU, most ICs were running quite cool, however the RAM looks off:


Clearly this is two banks of 4 RAM IC's and one of the 8 IC's is stone cold. The 3 voltages are present, so -5v on pin 1, 12v on pin 8 and 5v on pin 9, but my feeling is that with it being cold, it is probably dead, which probably accounts for the on screen corruption.

I think to be sure it's not a power issue, I'll add 5v from my 2nd bench PSU so the Electron PSU just has to deal with the -5v.

@rubber_jonnie

Ouch, quite hot for 4116 RAM...

Better to fit heatsinks or maybe replace them with 4164 RAM for reliability ?