I would probably recap it, but it may be ok.

As for those Startech units... the efficiency on them is horrendous according to the specs. Not sure I would touch one with a 10-foot pole.
I am kinda curious on who makes the PSUs for Startech as it is definitely a really, really, really old design.

I usually use a much newer Seasonic unit with an ATX to AT w/-5v adapter and call it a day. Can't really do that here easily with that PSU being like it is.

You could go really fancy and replace the innards with an ATX PSU then use an adapter and just wire up the switch wires to the original switch.

If it works as it is and has no burnt components or anything I would recap it just in case, even if it's just to breathe new life into it. Besides, AT power supplies are really easy to recap, none of those stupidly tall and thin capacitors for which it is almost impossible to find replacements.

Regarding the quality, I can't say really so I will leave that to the experts here, but if they didn't skimp with the capacitors it's probably at least decent.

cyclone3d wrote:

As for those Startech units... the efficiency on them is horrendous according to the specs. Not sure I would touch one with a 10-foot pole.
I am kinda curious on who makes the PSUs for Startech as it is definitely a really, really, really old design.

Honestly, I think the Startech AT units are fine, at least I'd say there a lot better than what I used back in the day (I even was surprised to find a few Nippon Chemi-con caps in there when I opened mine!). They may not hold a candle to more modern designs, but I don't think they pose any danger and they do their job well for AT systems that probably don't need more than 50-60W.

Thanks for the replies guys - so the consensus is tending towards recapping and that's something I can do, but I'm under the impression that you need to be a bit careful with the caps in a PSU to ensure that the relevant caps are "low ESR". I know how to find decent brands that are the correct voltage and uF rating, but beyond that I'm lost.

Any recommendations around that side of things?

Ideally you take the brand and series, find the datasheet, find your values and then find a suitable replacement. The voltage and uf actually don’t matter as much as the esr and ripple current.

CkRtech wrote:

Ideally you take the brand and series, find the datasheet, find your values and then find a suitable replacement. The voltage and uf actually don’t matter as much as the esr and ripple current.

Brand and series of the PSU or the existing caps?

Existing caps

Yeah, since it's a well known brand like Rubycon it should be pretty easy to find the datasheets. With that info you can shop for replacements, ideally you could buy Rubycons of the same or equivalent series for each existing cap, but since that's generally not possible here's the parameters I use when I search:

- Same voltage or higher
- Same capacitance (or slightly higher/lower if there are no exact matches)
- Around the same ESR, doesn't need to be exact (if there are some general purpose caps in the unit ESR won't be specified for those, so it doesn't really matter in those cases)
- Same ripple current or higher
- Around the same diameter (if it's too big it may not fit, if it's too small it may be tricky to get the leads in the holes)
- Always get caps rated for 105 degrees C! (except for the two big ones, those can be 85C)

I've used this as a guideline in the past with good success. In some cases, due to a lack of alternatives I've had to use caps with significantly lower ESR than the originals... according to some people this can cause stability issues but I've had no problems myself, so I don't know how low you can go with ESR (YMMV of course).

Pretty much a high five from me to TheMobRules on his list of parameters. I follow the exact same ones when I recap.

I also have directly received a bit of a tip regarding stability issues by going with significantly lower ESR - specifically regarding an AT power supply as the improvement of impedance capacitor technology has greatly improved over 20+ years. I backed off a bit from using the best of the best for that recap - stuck with the same brands but just used a slightly older series.

But hey - when it comes to nitpicking, it really isn't that big of a deal to drop another 30 cents here or 40 cents there in case you want a few alternative candidates.

This is a situation where it'd be interesting to see how the Rubycon caps measure with an ESR meter after all these years. There are so many devices this age and older that still function, I'd love to know if the caps really do need replacing or if it'd be safest for the unit to not be modified.

If you do replace the caps, it'd be awesome if you could measure them or send them to someone who could.

The only thing I see as lacking compared to modern systems (considering design wattage) is the input filter. The simplest method of upgrading depends somewhat on what line side connectors the PSU features. Do you have a type F appliance interconnect on the PSU for daisy chaining to your monitor, or does it only feature the C14 connector?
https://en.wikipedia.org/wiki/IEC_60320#/medi … _back_panel.jpg

Thanks for taking the time to reply guys - a set of simple to follow rules is exactly what I was after thanks TheMobRules 😊

gdjacobs wrote:

Do you have a type F appliance interconnect on the PSU for daisy chaining to your monitor, or does it only feature the C14 connector?

Yes it does have the daisy chain socket but I never use those for what it's worth.

Well, if it's mounted separately from the C14 socket, I think you can pick up something like this* and install it.
* https://www.digikey.com/product-detail/en/del … 1155-ND/1739358

Otherwise, it might be difficult to fill the cutout, so you'd need to find something that perhaps mounts to the back of the existing plug or is chassis mounted as close as possible to the plug.
https://www.digikey.com/products/en/filters/p … c025b&quantity=

Although if you don't care about RFI that much, it obviously doesn't really matter.