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[Weaver]

I’ve got a heap of old Netgear DG834 v3 modem/routers lying around but some have no working dc power bricks to go with them.

Does anyone have a source for ultra-high quality dc power supplies/bricks?

Must be stiff and ultra low noise. Can't remember the specs for that Netgear device offhand, would have to look up polarity, current draw etc etc. If I could run the damn things off a lead-acid battery then I would. (Electronics ignorance?) Would be bliss, perfect output quality and no UPS required.

There are also a lot of these fine modem/routers advertised on ebay sans psu for around £10. In any event would want modern reliable units instead and additional spares given that the old power bricks are the bits that seem to go first.

[PhilipD]

Hi

If the original power supplies were heavy bricks (transformer type) you should go for something similar, this is because the internal electronics may not be designed for the noise that's delivered from switch mode power suppliers which are common now.  A transformer is a transformer so it wouldn't really matter who made it or the quality, as long as it was rated correctly.

I'd also question though using older routers/modems.  They may have been great at the time, but the capacitors in them are rated for just thousands of hours and these components still age and start breaking down even if not being used, i.e. capacitors are perishable and have a shelf life.  The degrading of these components raise the noise floor and can make for unreliable operation.

Regards

Phil

[HPsauce]

I tend to collect old power bricks and have a surplus of them with quite high ratings, often from devices like scanners or NAS boxes but with the common 12V plug used by many such devices.
My experience is that the routers fail more often than the bricks though..... (not that I'm immune from the latter)

[Weaver]

@PhilipD -thanks for that important point. I hadn't thought of that. Particular types of capacitors? Electrolytics, tantalum so on..?

The reason I'm thinking about using these old DG834 v3 devices is that on my particular ancient TI DSLAM these modems are possibly still the winners by a mile in comparative testing against the modern modems Ive put up against them (Zyxel, Draytek Vigor 130, DLink DSL-320B). The old Netgear devices are soo aggressive, very high ds sync rates, us not particularly good.

Perhaps I should consider doing some surgery?     (hardly think so)

I will get hold of the most recent devices I can (which would mean about seven or eight years old) and have a competition between them on performance.

I have also found some weak evidence that different individual modern modem units differ in performance, but the effects of DLM are possibly enough to ruin such back-to-back tests.

[HPsauce]

Particular types of capacitors? Electrolytics, tantalum so on..?

Electrolytics, and frequently, especially on Netgear kit "of a certain age" 

You can see them easily if you open the case as they will have bulging caps:

[PhilipD]

Hi

@PhilipD -thanks for that important point. I hadn't thought of that. Particular types of capacitors? Electrolytics, tantalum so on..?

The reason I'm thinking about using these old DG834 v3 devices is that on my particular ancient TI DSLAM these modems are possibly still the winners by a mile in comparative testing against the modern modems Ive put up against them (Zyxel, Draytek Vigor 130, DLink DSL-320B). The old Netgear devices are soo aggressive, very high ds sync rates, us not particularly good.

Perhaps I should consider doing some surgery?     (hardly think so)

I will get hold of the most recent devices I can (which would mean about seven or eight years old) and have a competition between them on performance.

I have also found some weak evidence that different individual modern modem units differ in performance, but the effects of DLM are possibly enough to ruin such back-to-back tests.

As per the post by Weaver it is electrolytics that suffer because they contain a wet chemical that basically dries out, and the warmer the equipment runs the quicker this happens, and some types have expected life-time ratings in the thousands of hours.  It's very temperature dependent and dependent on the quality and if they've been over-rated for the equipment or not.

So aging happens when in use, and common to age quickly on modems that usually run 24/7 and quite warm as well, plus the circuit boards often double up as heatsinks, and the heat can end up travelling up the two legs of the capacitor making it nice and toasty inside.

Another issue was poor quality capacitors flooding the supply chain a good few years back now, they would often fail quite dramatically by bursting or bulging as in the pictures.

When they age normally and dry out, there is often no visible sign however they have degraded.

When capacitors are not used (i.e. the equipment is turned off for long periods of time), that can cause problems as well.

Regards

Phil

[sheddyian]

For replacement power supplies of many kinds, I usually visit local charity shops when I get a moment - most of them have a box of leads, routers, phone chargers etc.  In amongst the BT Voyagers with the USB connection, you'll often find branded power bricks for different routers / modems and the like.

Expect to pay 50p - £2 each.

You'll often find people optimistically selling old TalkTalk routers at boot fairs, but if they're only asking a couple of quid, they can be worth buying, as you'll get a PSU with it...

Ian

[Mooingall]

Much like Sheddyian is saying, I bought two BT Home Hub 3s a few years ago for around £6 delivered all in. One was brand new.

They come with 12volt 1amp power bricks. Good picture of the plug in this listing http://www.ebay.co.uk/itm/Bt-Home-Hub-3-0-300-Mbps-4-Port-10-100-Wireless-N-Router-BTHOMEHUB3-0-Type-A-/121703925830?pt=LH_DefaultDomain_3&hash=item1c561e8846

[ejs]

I replaced the original PSU from my Netgear DG834G v3 with a more recent one that came with an external hard disk. The original was rated 12V 1A, the newer one was 12V 1.5A. At the time I thought the newer one produced slightly less noise detectable by an AM radio near it. I did that about 2 years ago, doesn't seem to have caused any problems so far, the router is operating beyond it's life expectancy anyway.

[Weaver]

Thank you all very mcuh for these tips, keep them coming if you would be so kind.