Ubee D3.0 cable modem

I just picked one up at Goodwill. Brought it home and hooked it up, and
activated it throug Comcast. It came up working. Tried running a speed test from
the Speakeasy site. It started working, then slowed down, down, down, and
finally stopped. Couldn't get it to work again.

Can antone suggest anything I might be able to check to get this working? I did
open it and look at the caps - none are bulging, and a quick ohmmeter test
suggests they act as a cap as I switch the leads back and forth.

 

Hooked it up, called them and had them activate it.

 

I'll try #2. Many thanks.

 

Be careful with 'used' modems. Some may actually belong to an ISP like
Comcast and may actually be stolen. UBee was commonly used as a rental
by cable companies.

 

OK. I took the board out of the case and used the oscilloscope to look at the
signals on the caps. I did see a triangular ripple on several of them, which
matched a larger waveform seen on the ethernet connection, first seen on a small
disc cap near the ethernet connector, but also seem on the rest of the ethernet
connector pins..

I went upstairs, and tried the internet access - it works!

When working, the max download is about the same as the old DOCSIS 2 modem (this
is DOCSIS 3) at ~25Mbs. The upload speed is a bit faster, maybe 3.5 compared to
3Mbps.

Put the board back in the case, powered it up, and tried again - no connection.

It seems, what fixes it is to have the ground from the scope probe connected to
the outside threads of the cable connector, and the scope turned on. Turn off
the scope, and it quits working.

Now, I can really use some ideas!

 

Second try - it didn't show up for me.

OK. I took the board out of the case and used the oscilloscope to look at the
signals on the caps. I did see a triangular ripple on several of them, which
matched a larger waveform seen on the ethernet connection, first seen on a small
disc cap near the ethernet connector, but also seem on the rest of the ethernet
connector pins..

I went upstairs, and tried the internet access - it works!

When working, the max download is about the same as the old DOCSIS 2 modem (this
is DOCSIS 3) at ~25Mbs. The upload speed is a bit faster, maybe 3.5 compared to
3Mbps.

Put the board back in the case, powered it up, and tried again - no connection.

It seems, what fixes it is to have the ground from the scope probe connected to
the outside threads of the cable connector, and the scope turned on. Turn off
the scope, and it quits working.

Now, I can really use some ideas!

Oops. One more thing. It seems to occasionally quit for a few minutes aven when
I get it working.

 

I really appreciate the help. I decided I should remove the splitter that
separates the internet and TV signals. I hadn't remembered, but the splitter was
a "2-way splitter amplifier, which I had used to get a strong enough signal for
my computer TV tuners to get good digital signals.

With the cable plugged directly into the modem, it works great. With a splitter
for it and the TV, (5-1000MHz, amplified or not), it can't drive the modem. So,
it appears I have a signal strength, quality, and/or a splitter problem, or a
weak modem. It is good to know that it seems to work good with the direct cable
connection, so maybe this is a solvable problem. More experimentation tomorrow.

 

And trying it again later, it doesn't seem to be working at all. ugghhh!

 

I just got back from the Comcast office. Turns out this unit was rented by a
customer and is not usable by me, as Andrew suggested. IT would have been nice.

 

One reason to ALWAYS be wary about used modems. Generally, for D3
modems, only Motorola and Zoom seem to be widely available for retail
sale, with maybe some Cisco models on-line. Generally, RCA, UBee, and
other odd brands tend to be only available to ISP's.

 

That is helpful info. Thanks.