Hard wiring power to a modem/ router

Hi,

I noted at the weekend that when I twist the power plug, in the socket on the back of my Billion 8800AXL R2, the downstream SNRM increased by around 0.5dB. My immediate thought was to scrap the current plug/ socket arrangement and solder the power adapter cable directly to the Billion's circuit board. Has anyone experienced this before? And gone the same route?

Warranty issues aside, I can't see a downside.

Paul

I'd replace the power cable, or router, or both. Under warranty if still in it.

In reply to a post by RobertoS:

I'd replace the power cable, or router, or both. Under warranty if still in it.

It's a standard sized plug so I doubt a new power supply will fix the issue. I'd hazard a guess that changing the router wouldn't fix it either. I just think it's a consequence of the plug/ socket type set up.

Whilst sending it back for a replacement is an option, it's way more of a faff. It came from Amazon so they'll expect to receive the current one back before they send a replacement. I'll also have to reconfigure it, which is tedious. It is probably the sensible thing to do though...

Paul

Edited by youngsyp (Wed 14-Nov-18 12:37:20)

It could simply be the cable is damaged internally at the entry to or inside the plug. Or even dirty contacts on the plug or in the socket.

Edited by RobertoS (Wed 14-Nov-18 12:45:42)

I think it's more likely to be an issue with the contacts, judging by the behaviour so may buy some contact cleaner and go at it with a cotton bud. The contacts shouldn't be dirty as the device was new and has been in the same position away from anything that could get it dirty. There's clearly something afoot though.

Paul

In reply to a post by youngsyp:

Whilst sending it back for a replacement is an option, it's way more of a faff. It came from Amazon so they'll expect to receive the current one back before they send a replacement. I'll also have to reconfigure it, which is tedious. It is probably the sensible thing to do though...

When something I bought from Amazon didn't work properly they were very keen to send me a replacement immediately and let me return the faulty item with a month. It was a managed switched that lost its IP address. As it happens the switch started to work properly so I had to cancel the replacement.

Thanks but that's not my experience with them, hence what I wrote. The last time I had to return something, a faulty HDMI cable, it was a real fight to get them to send a replacement before receiving the return.

I'm also cynical that the replacement won't exhibit the same behavior as the current item. Typically you'd not notice what I did, unless you're looking for it.

Paul

What effect apart from a negligible change in SNRM is it having? A change of 0.5dB shouldn't make any difference to anything so why would you risk electrical safety by making this change?

Rubbish!

0.5dB makes a noticeable difference to the sync and thus throughput. It's around 8% of the typically available SNRM! On further investigation however, the fluctuation can actually be more like 1.5dB. Having fluctuations in the power supply the gateway is fed, is clearly not good for line stability. It generates errors and packet loss according to the monitoring on my line. It's also not particularly conducive to long life of the gateway.
I'm also struggling to understand how connecting a power cable directly to a circuit board risks electrical safety. The only reason for the configuration as is, is for convenience.

That aside, it seems the socket in the gateway either has a dry joint or is in some other way not permanently connected to the circuit board. As an experiment, I pressed the plug up in the socket and downstream SNR dropped to around 5.4dB. When I pressed it down, it went up to 6.8dB. It seems to be holding there now.
Regardless, instigated an RMA from Amazon and they're sending me out a new one. I'll just back up the config file from the current one, making the switch over less painful.

I have to say, Amazon have gone back up in my estimations as the return process, once I got to 'talk' to someone, was very painless.

Paul

Edited by youngsyp (Wed 14-Nov-18 23:04:03)

0.5dB is not significant in my opinion. Whilst it may be a good percentage of the SNRM at your "full speed" it is little compared to the full noise margin available - if you forced the line to 512Kb then the margin would be a lot higher and 0.5dB would be a small percentage of the total.

A dodgy power connection means it is right to replace the router but the extra 0.5dB in your original post is not going to make a major difference to speed, even 1.5dB as going to be a relatively small improvement.

I have to agree 0.5db is not a major difference, my line and most lines vary +-1db throughout the day. Irrespective, if the device is faulty - get it replaced which you have done.

Regarding hard wiring, it would be recommended to ensure a disconnect switch in sight of the device.

Removing the socket and soldering directly onto the traces on the board? Just suppose you've got to be careful not to(one day) yank the wire and rip the traces off.

In reply to a post by ian72:

0.5dB is not significant in my opinion. Whilst it may be a good percentage of the SNRM at your "full speed" it is little compared to the full noise margin available - if you forced the line to 512Kb then the margin would be a lot higher and 0.5dB would be a small percentage of the total.

A dodgy power connection means it is right to replace the router but the extra 0.5dB in your original post is not going to make a major difference to speed, even 1.5dB as going to be a relatively small improvement.

I strongly disagree.

I'm currently synced at 69129 with my attainable actually reporting 66996 due to currently having 5.7dB SNR.

That suggests that a loss of 0.3dB would reduce my connection by 2Mbit, which implies 1.5dB could be up to 10Mbit, a 1/8 reduction in sync speed if you are right on the edge of the limit. Its pretty much what HAS happened to my connection over the last few years, unfortunately due to crosstalk so not fixable.

Granted its probably not so linear in the real world, but I'd still argue its likely to be far from a "small improvement".

As it stands I'm keeping synced, but a sudden loss of 0.5dB and certainly 1.5dB could cause a resync. That alone is hardly an insignificant impact on your connection.

Edited by alexatkin (Mon 26-Nov-18 15:41:57)

Hi

No problem soldering direct if you know what you are doing.

It could be a slightly high resistance connection due to dirt or oxidation on the socket which may clean off, however the power isn't used directly by the modem as it goes through several DC-DC converters meaning a slightly poor connection is masked over by all the other noise and switching that happens before it reaches anything. Also because the power draw is quite high, a high resistance connection would either sort itself out or cause heating of the socket and perhaps complete failure.

It may just be noise being picked up by the wire from the power supply, and as you twist it, you might be increasing or decreasing the ability of common mode noise cancelling to work or not, i.e. twisted pairs picks up noise more evenly, therefore it's easier to filter that noise away. This could mean soldering the wires doesn't see an improvement.

Try twisted the power wire so it spirals, see if that helps first.

Regards

Phil