Low Signal to Noise ratio on one box

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I'm a Reliable Contributor
Posts: 366

Low Signal to Noise ratio on one box

TL;DR

I have a SA4250HD box where everything seems ok but the S/N ratio is low around 27 causing errors on channels.  Is there any diagnosis, other than a box going bad?

 

Long Version

I have an SA3250HD and an SA4250HD hooked up to a computer to record TV using SageTV as a software DVR and Hauppauge HD-PVRs as encoding devices.  I bought these boxes years ago and I have been using SageTV for this purpose with pretty much this configuration for over a decade. Nothing has changed in this setup for a while but I started having issues with recordings from the 4250 box. The HD-PVR doesn't like bad signals with pixelation, etc and it will often drop the recording.

 

The cable path comes into this part of my house, goes through a 4 port distribution (powered) amp and then goes into my internet cable gateway(Hitron CGN3) and these two boxes.  The speed on my internet is good at about 500/22 - better than what I am paying for so the amp doesn't appear to be the problem. The other cable box  has decent levels and SNR.  See the table below for various channels.

 Box 1  Box 2 
ChannelLevelSN LevelSN
4941427 1437
495927 1037
4961427 1536
497927 1036
4981427 1536
5011026 1137
502927 1137
5031026 1137

 

I have swapped the coax cables from box 1 to box 2 and nothing changed with the S/N - the bad one stayed bad and the good one stayed good.  That should rule out a bad coax cable or a bad port from the amp. I then swapped in another SA4250HD that I have and everything is good now with no errors.

 

Is there any diagnosis possible other than the cable box going bad?  That wouldn't be surprising as I have several other boxes that have gone bad through the years.

Resident Expert
Resident Expert
Posts: 3,832

Re: Low Signal to Noise ratio on one box

I would agree with your assessment of the box being "bad". It could be a number of things like a bad coax port - try wiggling it (moving it up/down for a few seconds) while connected to see  if the signal changes.

 

Your signal levels are actually a bit high. They should be closer to zero.  Try removing the amp temporarily.  Replace it with a splitter instead?

 

Could be a bad solder joint in the box.  Once you think you have nothing to lose you can take the box apart and diagnose with a multi meter. These boxes are so cheap (or free) these days on Kijiji or similar places that you can get another one.  Purchasing guidelines below.

 

https://www.digitalhome.ca/threads/guidelines-for-selling-and-buying-a-used-rogers-terminal-in-ontar...



I'm a Reliable Contributor
Posts: 366

Re: Low Signal to Noise ratio on one box

Thanks 57.   I will try your suggestions.  And I could try taking the box apart and checking the solder joint.  But I wonder if the issue could be some sort of internal amplifier or signal processor that is going bad.

 

Funny thing is that for my purposes the SA3250HD is fine although most people will not want them as I can only use Component out and I have no need for HDMI - most people will need HDMI outputs on the box. I wish Rogers would resell these as they probably just recycle them when they are returned by customers.