Motorola DSR-922 & Digital Signals

[nickf]

Howdy all,

When I bought my 4DTV receiver (Motorola DSR922) I also bought a new Precision High Stability 20 degree Digital LNB. For almost 2 years it has worked great. Now all digital signals show good strength but will blank out and them come back and do this so often its not worth watching.

I called a satellite repair guy and he couldn't figure it out other to say buy a new LNB. Anyone out there have any ideas or do I have to buy a new LNB. Signal strength on all the digital channels (even HBO) is 65 or over.

Nick

 

[Hermitman]

Here's some things I'd check before changing an LNB. How are your analog channels? Are they steady or also cutting in and out? If they're good, it's probably not an LNB. Recheck your connections on the back of the unit and at the LNB. Maybe they're loose or water got into an outside connector. While watching a show, press your right or left arrow on the remote. Looking at the Quality number, does it stay steady when the picture drops out or does it also go down? You could also check the voltage at the LNB connector to make sure it's steady and not varying. If this only happens when it's wet outside, maybe the cable cracked and leaked into the wires, causing them to short out occassionally. Just some thoughts. Good Luck.

 

[dfergie]

to SatelliteGuys...

 

[tdti1]

Most probably the lnb is going, what size dish do you have? HBO should be much stronger with a 10' you should be in the 80's-90's, what lnb do you have? is it a Astrotel? if you do not have c/ku this would be a good time to do the upgrade, if you do have ku-band how are the digitals there?

Yu can get a nice c/ku feedhorn package for a good price there is also a c/ku lnbf that works with 4dtv and is of low cost, I personally would go with a feedhorn and Norsat or Calamp lnb's but this will cost much more.

 

[nickf]

Thanks for the info. I will try it this weekend. Here is more information for Hermitman and tdt1. I have an 8' mesh dish with a Astrotel PMJ-LNB c H/S, 500K stability, 20 degrees K, bandwidth 3.4-4.2Ghz. It is only two years old.

When the picture disapears most of the time the signal drops to 1. On a few instances it will remain high. as for water, I live in Yuma Arizona and we have gotten about 1" of rain annually for the last decade. I have not tested the voltage at the LNB yet but will do so this weekend.

Even when I get the best numbers in Quality I lose signal.

 

[tdti1]

Astrotel... I would stay away from there lnb's. Do you have a feedhorn cover and a cap on the horn? it could be a split coax.

 

[Hermitman]

Just a couple more thoughts. The Quality number indicates that the unit is receiving DCII information from the LNB. If your Quality number remains high and the picture drops out, it may not be a signal problem but a processing problem in the unit. Does the green DC light on the front panel remain on when the picture drops out or does it flicker? If it remains on, the unit is receiving a steady DCII signal. Are you providing adequate ventilation for your unit so it doesn't overheat? Also, does this only happen with digital signals or with clear analog and VCII analog as well. Have you tried connecting your TV set to the other outputs on the back of the unit and seeing if the problem duplicates? Have you tried a different TV set? Just guessing here. Have fun.

 

[Al K]

I live in Yuma Arizona and we have gotten about 1" of rain annually for the last decade. I have not tested the voltage at the LNB yet but will do so this weekend.

Here in Phoenix, I've lost the signal from my C/Ku Dish twice in maybe 16 years. Once it was an LNB, and once it was corroded connectors from rain!

 

[cspiteri]

It could be TI from the military base. I`m in North San Diego county and we get a lot of that from the bases in this area.
Look at an analog transponder with your TI filters off. Often it will show up on analog as well. The TI filters in the 922 are not for digital. Go to the Ku side of the satellite and if that is giving a good picture without the dropouts, you can pretty much be sure your problem is TI

 

[nickf]

OK here are the stats on this problem, 8' Dish, Astrotel LNB, Receiver has adequate air, Line H = EC, Voltage is steady at LNB (20.62vdc), Quality number drops to 1, DC light flickers, this only happens with Digital Signals, does the same thing on different TV's and all Outputs of receiver. As for the base, all analog signals with the filter off work fine and I don't have Ku.

My assumption is that I need to upgrade and replace the LNB. I just want to make sure it's not the receiver thats the problem.

 

[Hermitman]

There's a couple more things I'd check. Have you done a soft reset on the unit? Just in case it's a software glitch. Lastly, I'd check the servo motor. Maybe it's jumping around on you. You could tell by listening to it on the LNB and see if it's making movement noises when the picture changes. Or wait till the picture is good then remove the +5 volts wire from the polarizer connector on the back of the unit. That will keep it from moving. If the picture stays steady, then the servo is drifting. If the picture turns bad it's not the servo. Then I would guess it's a short somewhere in the LNB causing an overload condition and the voltage regulator IC in the LNB is cycling on and off resuting in the picture cutting in and out. Although I'm not sure why it would work ok for analog but bad for digital. Maybe there's two different power circuits in the unit. Ain't this satellite hobby fun? Good Luck.

 

[nickf]

I now have no +5 volts and no satellite at all. Know any good repair places? OK, so I spent most of today fixing the power supplies to the unit (two bad CR's). All power is on and steady. I disconnected the+5 volts off the sensor and the picture still drops and the quality drops to 1. Since I fixed the power I now have higher quality numbers (up to 94) except HBO on G1. That's still in the high 50's low 60's. I am going to buy a new LNB, I will probably upgrade to Ku also at the same time so I will need to buy a new setup for that too. Back in 92 an ECHOStar dealer installed my dish and it says echostar on it. I'm not sure what everything else is except the LNB (Astotel).

 

[nickf]

Final outcome

Bought a Norsat 8115. Now I get Great reception in the high 80's low to mid 90's on everything but HBO. Trying to tweek receiver for best HBO (mid to high 40's). Everything else works great. Thanks for your help and advise.

 

[somery]

I did some tweaking yesterday and got everything better all across the arc, but HBO got worse and has sparklies now. Can't figure that one out....... CNN on the same sat used to have sparklies but i fixed those a lot better.

 

[dfergie]

Does skew fix the sparklie problem? if so maybe the feedhorn is clocked wrong...

 

[drhydro]

where at in the arc (lowest, highest, middle) is hbo at for you? The reason i ask is it could be a declination problem. Too much declination will cause loss of signal on sats in the middle of the arc, not enuff will cause loss on the ends of the arc.

 

[Grimgnaw]

I recently had the same Motorola 922 drop-out problem on digital channels when I switched from a dual C-band feedhorn to a C/Ku feedhorn setup . I inserted an inexpensive satellite-finder inline between the LNB and the 922 to see if the input signal was dropping out or if the receiver was the cause, and with its insertion the problem disappeared. Thus, it appears that a slight attenuation is all that is necessary between the LNB and the 922. The 922 quality dropped from 77 to 59 with its insertion but that is adequate for a perfect digital pic.

Switching C-band LNBs accomplished nothing. Likewise for every other tweak except as mentioned above. I hope to find alow level attenuator for the L-band frequency.
-------------------------
9' dish with California Amplifier LNB

 

[lonewolf85]

Man I was trying to figure out why this was not posted in the 4dtv area and then I saw the date of the first post and the last post man Grimgnaw you sould git some type of award for reviveing a two year old tread.

 

[Techfizzle]

i thought astrotel made good lnbs?

 

[Grimgnaw]

Whoops, the culprit was the noise entering the 922 via the 120 vac power line. I found this when I moved it to another room to work on it. There the dropouts disappeared when using an extension RG-6 line from the LNB, a different TV for display and power from another part of the house. I then moved it back with the rest of the receivers and brought in the AC power via an extension cord. Interestingly enough a second 922 has not had the problem. The second unit is 3 years newer and power supply filtering is probably better. The HBO channels were the most affected and the second unit does not access those.

Yes, this is at the end of an old thread I encountered via a Google search, but there was no happy ending to it yet so I hope this helps when someone else has this same problem. Just try powering it from a plug closer to the main supply box. Just for insurance on the test I included an isolation transformer in the power extension. That isolation transformer was not sufficient when tried on its own.

By the way, a repeat try using the Satellite Finder fell flat on its face doing nothing. Not sure now why it worked in the first place. Some condition was obviously different.