[WXC/VFX] At last!! RTA1320 + WRT54GS For The Win!!

Forums › One New Zealand (including Vodafone, WxC, Farmside) › [WXC/VFX] At last!! RTA1320 + WRT54GS For The Win!!

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#232264 8-Jul-2009 07:51

Both SRA and the other Bit Stream one are both ticked. Have tried both ADSL and ADSL2+, and M-Mode on and off. After swapping with another modem and different jacks and power plugs (nothing else in the house is plugged into any jacks - so I'm isolated alread) it looks as though it's the modem. The linksys WAG54G2 doesn't drop any connections.

Probably the usual story of dying caps on the RTA1320, which makes a high pitched whine when booting up. A couple of 'em look bulged - I'll test them today and replace and see what happens. If not, I'll try a TP-link TD-8840. I just hope those can be half-bridged.

magu

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BitSignal

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#232268 8-Jul-2009 08:03

Wait, does it make the high-pitch noise when booting up? Toasted. Same thing when my RTA1320 was dropping out, a couple of weeks ago. Had Orcon send me a new one and all is good again.

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Ragnor

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#232486 8-Jul-2009 14:44

You can get another "as new" Dynalink RTA 1320 off trademe for ~$25, it will probably die in around a years time though.

I saw a few Linksys AM300's on trademe..

Edit:

http://www.trademe.co.nz/Computers/Networking-modems/Modems/auction-227736014.htm
http://www.trademe.co.nz/Computers/Networking-modems/ADSL-modems/auction-228403795.htm

sultanoswing

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#232551 8-Jul-2009 15:46

Can the AM300 (or the TD-8840/10 for that matter) be operated in half-bridge mode to allow for routing of PPPoA connections?

Cheers!

Ragnor

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#232706 8-Jul-2009 19:43

Yes of course otherwise I wouldn't be mentioning it

sultanoswing

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#232821 8-Jul-2009 22:26

To cap this thread off on a positive note, I successfully replaced all the capacitors on the RTA1320 tonight, and she fired up straight away and has held an ADSL2+ connection all evening, with no high-pitched hum on boot up. I have a sneaking suspicion I'd been negligent and hooked the modem up to a 12V DC power supply last night, rather than its proper 9V AC supply. I realised this when I found the unit's correct power supply still in the box the modem came in! (and so no need for bad Trademe feedback on the guy I bought the modem off *ahem, my fault*)

I've learnt a lot about these little units in the last 24 hours!

For good measure I've affixed a small heatsink onto the broadcom chip, and will soon attach a small 9v fan into the top housing, powered from the unit's 9v supply. At the moment it's running with the top off.

Is all this worth it for a $25 modem? You bet - educational experiences usually cost! :)

Niel

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#232857 9-Jul-2009 06:14

The first thing the modem does is rectify the AC so 9V AC will become 9 x 1.414 = 12.7V DC. But the AC power adapter is unregulated and delivers more than 9V. Actually it is only 9V with the correct input (probably 230V, not 240v) and while delivering the maximum current (1A?). So typically the rectified AC will be around 14V or even more.

A switch mode DC power adapter will be accurate but noisy, which could upset the modem if they have insufficient filtering (especially when designed for an AC or linear power adapter). If it is a linear power adapter then the output is most of the time unregulated and will still be around 13V or 14V with a light load and fluctuate with different mains voltages.

A higher voltage is better for capacitors, because they see less ripple current. Higher voltage is worse for regulators, because they see a higher voltage drop so dissipate more heat, but not that much if it is a linear regulator. Most heat comes from the modem chipset and not from the power supply, so different voltages have little effect on the heat.

The input gets regulated inside the modem anyway, which is why Dynalink use cheap AC power adapters.

I'm an electronic engineer and the last couple of years we've spent lots of time specifying and sourcing power adapters. The good think is that both AC and linear power adapters will soon no longer be available for sale. Everything will be switch mode and so everything will be DC. Less confusion. This is driven by standby power requirements. You will no longer be able to import a product if it does not comply with efficiency regulations.

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xlinknz

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#232970 9-Jul-2009 12:17

Sounds similar to my RTA1320 woes

For two years my RTA1320 worked without issue and then some months after my exchange went dsl2+ it started becoming unreliable...dsl disconnects

I upgraded the firmware to 3.63u after I read it improved reliability with new Alcatel DSLAMs but alas no difference. I asked Dynalink [who were quite helpful] whether these units suffered overheating problems. They said no. They also could not tell me from the S/N how old the unit was

These disconnects also continued [although less frequently] when forced to g.dmt, I even ran the unit open by an open window !

I borrowed a Cisco 877 and the problems stopped, I also tried a dlink 604T and the problems didn't occur.

Having concluded the RTA1320 was the issue and not wanting to get a 2nd hand one wihtout knowing how old it was or buying a new one. I have since replaced with a brand new Thomson ST536v6 for $18 [+ 2 new filters] which works without issue. I have yet to try configuring it for half bridge as my rta1320 was.

richms

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#233063 9-Jul-2009 14:58

I have found that linear power supplies are noisier then switching ones - once I swapped the linear out for a switcher on my router the disconnects and reboots stopped when turning things on and off, and sync speeds went up sligtly. And I dont know why since there just seems to be another switching regulator in the router.

Richard rich.ms

Niel

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#233260 9-Jul-2009 22:36

Linears have minimal filtering, they only smooth ripple from 50Hz mains. Switchers generate HF noise so they require wide band filtering. Also switchers are relatively new so go through newer versions of EMC/EMI compliance standards which are tougher than when older linears went through standards many years ago. Today you can;t get a linear through standards any more, they are too inefficient (something like 60%, needs to be I think over 85%).

And if you mean AC rather than linear, then there is absolutely no filtering in the power adapter and the filters in the modem have to work overtime to remove spikes coming through the mains.

You can never have enough Volvos!

richms

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#233266 9-Jul-2009 22:48

It was a dc unregulated supply that came with the router that blocked up other outlets - replaced it with a switching one which is nice and slim and things are just better. Seems that they got a switcher in the states with it so I think it was just them being cheapskates when packing the aus/nz model... thanks netgear...

Richard rich.ms

sultanoswing

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#240339 29-Jul-2009 22:13

Fan is mounted and running sweetly, off a separate 9V DC supply (all soldered in & neatly tucked away).

The efficient-design engineer in me though is still dreaming about PPPoA->PPPoE pass-through, so...

Draytek Vigor 120 modems $133 in NZ, $70 in Aussie.

Our NZ peso ain't THAT bad in comparison, is it? Of course the downside is having to live in Aussie, as the Aussie retailers won't ship to NZ.

/me checks diary for next trip to West Island....

richms

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#240344 29-Jul-2009 22:20

aus pc market will, and the shippings not too bad when I last enquired. But funnily enough when shown that I can land one from retail at $30 below the cost from dove, they came thru with a better price for my mates account...

Richard rich.ms

Ben

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Vend

#240674 30-Jul-2009 17:33

Niel: It is worth getting a cheap 1-week mains timer to restart the modem weekly, as you will lock up after 2 or 3 weeks anyway.

Any you'd recommend? I'm desperate for something that will bounce my router at 2 in the morning every few days.

richms

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#240689 30-Jul-2009 18:06

I got several digital timers at bunnings for $7-8 about 6 months ago to turn lights on and off when not at home. Do the trick fine - the cheaper clockwork ones only do it daily and the resolution is 15 mins so thats a long outage of internet at the minimum duration.

Richard rich.ms

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