Happy Bunny - Replacement power supply

A place to discuss everything Dragon related that doesn't fall into the other categories.
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vdc300
Posts: 34
Joined: Mon Mar 30, 2009 11:17 am

Happy Bunny - Replacement power supply

Post by vdc300 »

Big smiles from me this morning :D .

A couple of weeks ago my power supply gave up the ghost. Off to make a cup of coffee, come back to a blank tv screen and a very bad smell. PANIC sets in, switch everything off. I feel the power adapter and it's super hot. My first thought is despair, then anxiety, what has it done the the Dragon's delicate chips. After a short trip down the denial (i'll wait till it cools down and try again), despondency and then the acceptance route, I looked at my options.
I moved from the UK to Australia 6 months ago (of course I shipped the Dragon) so waiting for a power supply from ebay that someone would ship to OZ seemed unlikely and expensive plus I may have a dead dragon. Decided the best option was an older PC power supply, Yesterday I wired it up, and I'm pleased to say my dragon has survived a 24 hr burn test, running a program peeking random memory locations.
I've managed to keep it tidy by putting 1 cm cut in the ribbon cable from the internal PS Board to the dragon motherboard (pin1-4), removing those pins from the PS board and connecting up to a 4-wire cable that runs through the hole left by removing the 9-pin power socket on the PS Board. My PC power supply has a switch so no need to rewire the dragon switch. The Dragon motherboard is still attached to the Composite monitor out and the Modulator as before.

The reason for this email (apart from the need to share the relief) is that I'm sure this has been done up and down the country, so my question, Is there anything I should be looking out for with using this method that would spoil my fun? I'm planning to run a 3.5 drive I have using the PC power supply along side the two 5.25 drives i have that run from their own supply.

Thanks

Paul
sorchard
Posts: 530
Joined: Sat Jun 07, 2014 9:43 pm
Location: Norwich UK

Re: Happy Bunny - Replacement power supply

Post by sorchard »

Nice one. Always very satisfying to bring a Dragon back to life :D

The only bad thing I can think of is if you're unlucky and a fault develops in the future that draws heavy current from the supply. A PC supply will be able to deliver a considerable amount of power that will melt PCB traces or burn wires.

It might be worth considering some fuses to limit possible damage. I'm not sure what would be ideal but maybe 2A on the +5V line and 500mA on the others. Fast blow fuses would be the first choice If they'll work without nuisance tripping. This is just for the supply to the Dragon; a drive can be connected directly as it should be designed to run safely from a high current PSU, though that could be another can of worms ;)
Stew
vdc300
Posts: 34
Joined: Mon Mar 30, 2009 11:17 am

Re: Happy Bunny - Replacement power supply

Post by vdc300 »

Stew

That's good advice. Just about to order some fast blow 3A fuses for another project and the thought never occurred to me, I might go for fuse holders as well and they can live in the dragon.
Brilliant

Thanks

Paul
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