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Small +5/+12 disk PSU?

Chuck(G)

Chuck(G)

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Jan 11, 2007
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The small PSUs used for external drive boxes seem to be disappearing, or the available ones go light on the +12 side.

I was thinking about cannibalizing a few used TFX PSUs. Any other suggestions?
 
I can still find plenty of used 3,5" external drive cases with their bricks. If those aren't sufficient there's good old Meanwell: https://www.jameco.com/shop/keyword=5V-12V-Meanwell

Unless you can get those TFX PSUs very cheap of course but imo they could be more useful to replace the PSU in old gear which require voltages other than +5 / +12 only
 
Basically 3A@12VDC and maybe 3A @5VDC. Some of the old drives require quite a bit of 12VDC which made me think of TFX supplies. Remove the box and fan and you should be left with a decent-sized PCB. Or so I think...

Since I already have FH 5.25" drive boxes, I'm looking for PSUs to fit. But it might be cheaper just to find another used external tape drive box (DLT, LTO) and use that.
 
A good source for +5,+12 power bricks is usb/sata ide hard drive adapters.
They are pretty cheap. Just ignore the adapter and use the power brick.
The one I got is +5@2A +12@2A. If I need more power I buy a mean-well.

I did build a SBC Z80 system in an external SCSI cabinet.
So external SCSI enclosures are a good source.
 
Thanks, but not looking for a brick--heck, I've got an old Compaq LCD brick that supplies both 12VDC and 5VDC, at 2.3A and 2.0A respectively. Bricks aren't difficult to find, if you want them.
 
jlang said:
A good source for +5,+12 power bricks is usb/sata ide hard drive adapters.
Click to expand...
Those Chinese power bricks are cheap for a reason, Garbage / Dangerous, I've had 3 and not one lasted a year, The labels on them certifying ROHS, This that and the other are total BS. I use a PSU from an old Jamma cab, It's way OTT for what i use it for but it's good and i make my own power leads.
 
If you're referring to the 4869 enclosures, I ended up using a Mean Well PD-25A in one of mine. It doesn't meet your specified amperage requirements but it works fine for a YD-380 floppy. They also make higher wattage models in the same form factor I believe
 
Chuck(G) said:
TFX supplies
Click to expand...

Huh. I had to look up what a "TFX" supply was; it's basically a fatter FlexATX? I'm not so sure about the prospects of skinning the metal box off; those things are usually pretty tightly packed inside, the bare guts are unlikely to be much smaller than the case. If you're trying to fit inside a box intended just to hold an external floppy I'd think a PicoATX power supply would be a better bet, or if you're fine with the AliExpress-quality route (which is what you're getting with a PicoATX PSU anyway) it's easy enough to find little off-brand boards like this that should be a direct replacement for the kind of PSUs that came in old FH drive enclosures.

That said, I use an old FlexATX as my bench power supply, it works fine. Bonus is it's old enough to have the optional -5v line that most ATX power supplies made anymore don't have. Downside is it doesn't regulate the 3.3v line properly unless there's at least a good fraction of an amp on the +5v line, but I gather most newer supplies don't have that problem and of course it wouldn't matter if you were just using +5/12v anyway.

Last year I guess I posted a picture of my solution to the "needs a minimum load to regulate properly" problem: If I'm tinkering, it's Christmas.

index.php
 
Well, I took a bit of time this afternoon and fitted a spare power supply into a box that held 2 4GB Seagate "Hawk" drives. Cleaned up some wiring (things are a bit ugly as these drives are SCA) and brought the box online. Discovered a backup made about 20 years ago (Windows 98). Found another PSU in my hellbox--a Skynet ±12VDC +5VDC one, rated at 2A on both the +12 and +5. Replaced a bad capacitor, but didn't test it fully--later maybe.

Thanks for the Amazon link--that little PSU looks pretty spare, particularly in the filter capacitor area.
 
Chuck(G) said:
Thanks for the Amazon link--that little PSU looks pretty spare, particularly in the filter capacitor area.
Click to expand...

Yeah, it doesn't exactly look "overbuilt", does it? It also says in the fine print that it's only good for 500ma on the 5v output without better cooling for the regulator. It just, well, looks shockingly like some of the PSUs I remember from TRS-80 disk boxes back in the day.

I'd bet you could find better, or at least claims to be better, for pretty cheap with enough spelunking on AliExpress, but of course quality is going to be a roll of the dice. Flip side: it's not like it's really any different with the supplies that do come with a case around them, I suppose.
 
I looked at the Amazon bargain PSU and wondered about any safety features. For example, where's the over-voltage crowbar (usually an SCR across an output)? Aside from my linear supplies, most of the small switchers that I have are far more complicated than that thing.
 
This one grabbed my attention. Aside from no mention of the actual size, I wonder if the specs listed (assuming they are accurate) are suitable for an external drive enclosure?
 
Chuck(G) said:
Looks promising, but no photos, nor any description of physical size. :(
Click to expand...
I know, I don't get it. I have some interested in it for a project but why wouldn't the size be there - I suppose I could ask - it's also on the bay.

From a buyer this pic is posted, I get some idea of the size from comparing the cables but given the details that are there, it makes me wonder. Searching the model # was unproductive.
 
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