! ! 3 1/2" PC Drive/s on a beeb ! !

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sydney
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Re: ! ! 3 1/2" PC Drive/s on a beeb ! !

Postby sydney » Thu Mar 24, 2016 10:20 am

I think putting the cable in the wrong way round will cause the led to be constantly lit. Perhaps you have shorted one of the wires when you removed the pc twist.

rharper
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Re: ! ! 3 1/2" PC Drive/s on a beeb ! !

Postby rharper » Thu Mar 24, 2016 5:34 pm

BeebMaster wrote:
retroclinic wrote:
textbook wrote:
Thx for posting that link.. might find a few uses for one of those.... gotta be worth a fiver with free delivery. :) even if only for bench testing purposes.


[-X They go bang with more frequency than Beebmaster's LV ROM Drives! Stay well clear of those china cheapie PSUs. They also run VERY hot, when they do run at all!


I only just saw this, and that item is still available. It's something I could really make use of, I've never seen a mains PSU ending in a hard drive connector like that before. I'd probably have bought a couple of dozen of them if it wasn't for this warning. Anybody know of a reliable substitute?

I have used a good number of these cheap psu's over the last few years, mostly for powering internal 3.5" floppy drives as external drives on beebs and electrons.
You can of course chop off the molex connector and solder on connectors for other equipment.
About 4 years ago they did indeed get very hot and if left on for a few hours might go bang! I tended to use them just for an hour or 2.
I have removed the top and drilled holes for ventilation to improve the dissipation of the heat.
However, the ones I have bought over the last 2 years look the same but are completely different.
The originals have a board completely packed with components, many large caps, that took up about 80% of the inner volume so only 20% air for taking up the heat!
The recent ones have a sparsely populated board with about 95% inner volume air. They get warm but no more so than any other psu. I have left them on 16h and they are no warmer after 16h than after 2h.
It is possible that I have just been lucky with my recent purchases.
I got the last lot here http://www.ebay.co.uk/itm/HDD-POWER-SUP ... OC:GB:3160
Ray :)
Raycomp

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1024MAK
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Re: ! ! 3 1/2" PC Drive/s on a beeb ! !

Postby 1024MAK » Thu Mar 24, 2016 6:13 pm

There are a number of problems with the cheap PSUs:-
  • Safety issues - some do not meet UK or European standards for the clearance/creapage gap(s) between the mains side circuitry and the low voltage output circuitry on the circuit board, without opening and destroying the transformer, it is very hard to tell if there is a proper isolation barrier between the primary and secondary windings, any wires inside the PSU should be restrained to ensure if one becomes loose, it cannot move and touch another component or conductor (a mains wire touching the low voltage section or a low voltage output wire touching the mains circuitry) but often the wires are loose,
  • The bare minimum of components are used, this means NO interference suppression inductors or capacitors on the mains input side, NO mains surge protection and only one filter capacitor for each output voltage rail (a good PSU will have a capacitor/inductor/capacitor filter),
  • The "regulation" circuit is often a basic design and may not give good regulation. Note also, a lot of switch mode PSUs only regulate one output rail.
  • The components are not high quality, and the values used for the capacitors may be somewhat random. In some (different) inexpensive PSUs I got to see what they were like, the higher current ones (according to the label) had smaller value capacitors than the lower current rating units!
I know it is difficult to get decent combined 5V and 12V power supplies. But I strongly suggest you pay the extra and get a good quality PSU from a well know quality supplier in your country if you can.

Also, some of the more modern 3.5" drives often only use the +5V line (they don't need a +12V supply).

Mark
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BeebWiki‬ - for answers to many questions...

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MartinB
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Re: ! ! 3 1/2" PC Drive/s on a beeb ! !

Postby MartinB » Thu Mar 24, 2016 8:01 pm

Genuine APD PSU's are good quality in my experience but are necessarily more expensive. There are lots of different permutations of voltage and current - have a scan on ebay for something like 'APD 5v 12v' to see the options and prices. I've actually run Beebs off the DA-45C01 (5v/4A & 12v/2A and I added a small -12v regulator) but they are harder to find and can command significant money. I got one from a car boot for 50p :D but I will shortly have another because earlier on this evening, I acquired one through an ebay Best Offer of £8.50 inclusive... =D> (I obviously didn't want to post this until I'd snaffled it... :wink: ) You obviously don't need the capacity of the 45C01 for disc drives, many of the lower spec APD devices would be fine.

beebdidi
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Re: ! ! 3 1/2" PC Drive/s on a beeb ! !

Postby beebdidi » Fri Sep 23, 2016 2:06 pm

Hi,
Found this 'old' article :
http://amigadrive.blogspot.fr/2013/11/h ... loppy.html
It might be possible to do the same with BBC B or Master ?

Cheers


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