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bchandler02

join:2011-07-08
Oklahoma City, OK
reply to xymox1

Re: Upgrade from dpc3000 to dpc3010 and slower upstream speeds

This was a very interesting post, thanks for sharingso much details!


xymox1
Premium
join:2008-05-20
Phoenix, AZ
well im not actually done yet. I got a very recent production SB6180 last week. It had some production changes and had some caps right where i decided to put them ! Only 2 tho where I have now put 17 all over in key spots.

But this caused me to look over and test the sb6180 all over again.

In fact I dont think its a equal to the dpc3010. While the RF section *might* be better the poor design of the power supplies to the BCM3380 is a big oversight. The fact they had to add caps later in production - tacked down with silicone - is clearly a rather emergency measure to fix a known issue hurridly rather then do a board redesign.

The complete lack of electrolytic caps on the power supply rails to the chips is almost bizarre. Measuring the noise on these rails reveals what seems clearly like too much noise for proper operation.

I would think this would result in strange behavior, more then normal reboots and hangs.

I also now see another big difference bewteen the dpc3010 and sb6180. Under the bcm3380 chip are small caps on the power leading into the chip. These are standard stuff on any CPU. They keep noise out of the power going to the CPU. On the SB6180 the values of these caps is 10 times smaller then on the dpc3010. In fact they are so small it seems really weird. When you add on to that the lack of electrolytic caps after the regulators then this design seems dangerously noisy.

So my opnion now is that the DPC3010 out of the box is a superior device from a engineering stand point.

Also the DPC3010 is much easier to mod and add further tweaks to to make it even better.

Now BOTH the SB6180 ( and 6580 ) and the dpc3010 ( dpc3825 ) have SERIOUS thermal management issues and run WAY TOO HOT. Ive now clearly seen that older units rather quickly loose performance as the heat bakes the bcm3380 and degrades its RF performance. All the used older modems I have seen all have degraded RF performance and this must be related to the bcm3380 and I feel heat. So the addition of a fan to blow the heat outta these boxes will keep performance up over the life of the unit. Not to mention the huge increase in lifetime cooling the BCM3380 down will provide. The complete stupidity in allowing these super high temps on this chip are just stunning. These are all going to fail.

Overall I dont like the design and layout.


xymox1
Premium
join:2008-05-20
Phoenix, AZ
HOWEVER there is one very important thing that might make the SB6180 a better choice, a better heat sink. The sb6180 is far more likely to survive longer from the excessive heat then the 3010. The thermal management on the 6180/6580 is better and this alone might be a reason to buy it over the 3010...

Adding a small fan to these tho then makes the 3010 the better choice as it has better electrical design and better firmware support.

The above is my final conclusion.


dvd536
as Mr. Pink as they come
Premium
join:2001-04-27
Phoenix, AZ
kudos:4
reply to xymox1
current firmware is may 16 2011. your firmware is old.
--
Despises any post with strings.


xymox1
Premium
join:2008-05-20
Phoenix, AZ
Yes, as is covered in the thread many posts ago my firmware was old. Important to read the whole thread before posting. In fact there is a *** UPDARE *** i put on the very first post that says that.

thedunlap

join:2005-01-31
Gainesville, FL

1 edit
reply to xymox1
I acquired a DPC3010 when Cox first started offering them for free and my experience was poor.

First, I discovered that the Cox caps were much stricter on the DPC3010 than on the SB6120. In fact, for about a year, I experienced a 20-35Mbit powerboost advantage over the 55mbit limit on the DPC3010. However, that advantage was eventually and rightfully taken away by an update.

Secondly, and most importantly, my DPC3010 was always flakey. Which I found very odd, especially b/c the DPC3010 always had 3-4db advantages (higher SNR 4+db) (lower upstream -4db) compared to my SB6120. I think you hit the nail on the head with your analysis of the the deficient heatsink in the DPC3010. At the time, it was not unheard of to be 1-2+Tbytes/month, and my guess is it overworked the broadcom chip and things got too hot in the DPC3010, which caused it to flake out.

Switching back to the SB6120 always resulted in a rock solid and stable connection in comparison.


floridaguy

@cox.net
reply to xymox1
At first, I was like this guys a little crazy. But, then I realized he's just my kind of crazy. Awesome thread. Xymox1, if you ever get into router modding, would be an insanely interesting thread. Only thing I wish you would have done differently was figure out a more aesthetically pleasing design scheme for your frankenmodem fan mod.

Btw, xymox1, how often are you calling in to get your account's MAC switched?