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5LNB Failure (Maybe??) - Or Maybe a Receiver Issue
Hi, All.
This posting is a continuation of the thread that I started in the Installation Forum, but now I think my problem may be with my H20-600 receiver, so I'm moving it over here and I'd like to hear your comments. Here's what I found with my troubleshooting yesterday evening.
First, my old RCA receiver continues to plug away, faultlessly receiving all it can from the 101 Sat, with absolutely no issues.
However, I have come to suspect that my new H20-600 isn't so bulletproof. First, to recap, I lost most of the 119 and 110 Sats (all even numbered transponders to 0 and some of the 119 odd transponders show attenuated signal levels over what they were when I originally installed this thing). I decided to look at the DC voltage integrity both from the H20 and from the old RCA. I first looked at open circuit voltages coming out of each receiver. No problems there - with even transponders selected I saw slightly more than 18V, and slightly more than 13 when the odds were selected. So, I hooked up an Accutrac 22 PRO in-line between each receiver and several of the input ports to the AT9 5LNB. The Accutrac allows you not only to see a measure of the RF signal strength from the LNB whether or not you have a receiver connected (it sources its own DC control and 22KHz tone to allow testing individual downconverters), but it can pass-thru the signals from a receiver and will let you see the LNB response to receiver control.
So, with the Accutrac connected to the old RCA, I saw between 190-220mA sourced from the receiver to the mux at the LNB feed. WIth the RCA disconnected and the Accutrac operating on its internal battery, the control voltages and currents were similar.
BUT, with the Accutrac connected in-line with the H20, it only showed 24-30mA sourced to the LNB mux. I also used the Accutrac from that same port to the LNB, but with the H20 disconnected, and the current it provided was on the order of 170-200mA.
I think that my H20 no longer can source enough current to get all the LNBs to switch polarization properly. Interestingly enough the 101 Sat seems quite happy with that 30mA, but the others just don't seem to switch properly.
I also looked at the DC resistance of each port to the LNB mux with no receivers connected, and I measured about 60Kohms at each one... so no DC shorts or opens are present in the system. Can't speak for the RF impedance of each one though -- the network analyzer is too big to "borrow" from work! 😉
Any additional thoughts from you guys, before I call DTV and ask them about H20 warranties?
Oh, one final note to greywolf. I reset the H20 several times during the course of the past few days, and when it no longer decided that it could see the 119 Sat transponders (as it did when it went thru power-on reset), it refused to include the Test Channels for anything except the 101 Sat in my channel guide. So, I couldn't use the Test channels to check any of the other Sat feeds from the LNB.
I'm asking for more comments from you all because I'm still not 100% convinced that this is a receiver problem. I noted this morning, since we have a clear and sunny day here today, that I have partly recovered some signal on those 119 odd transponders that were attenuated last night. Do I have a receiver problem here, or do I have a case where I have something funky with the LNB that causes it to draw more current when cold/damp than when warm and toasty? I am thinking that maybe the H20 simply has a current limiter in it which is preventing it from sourcing too much current in the event of a short on the line... that may not have been included in the old RCA design. I'm speculating here, mostly because I am an Electrical Engineer (and an old RF antennal guy) and I don'[t have the schematics here to really drive this issue to ground. I'm hoping that one of you guys have access to more detailed technical info than we do!
Thanks in advance for any help you can provide!
This posting is a continuation of the thread that I started in the Installation Forum, but now I think my problem may be with my H20-600 receiver, so I'm moving it over here and I'd like to hear your comments. Here's what I found with my troubleshooting yesterday evening.
First, my old RCA receiver continues to plug away, faultlessly receiving all it can from the 101 Sat, with absolutely no issues.
However, I have come to suspect that my new H20-600 isn't so bulletproof. First, to recap, I lost most of the 119 and 110 Sats (all even numbered transponders to 0 and some of the 119 odd transponders show attenuated signal levels over what they were when I originally installed this thing). I decided to look at the DC voltage integrity both from the H20 and from the old RCA. I first looked at open circuit voltages coming out of each receiver. No problems there - with even transponders selected I saw slightly more than 18V, and slightly more than 13 when the odds were selected. So, I hooked up an Accutrac 22 PRO in-line between each receiver and several of the input ports to the AT9 5LNB. The Accutrac allows you not only to see a measure of the RF signal strength from the LNB whether or not you have a receiver connected (it sources its own DC control and 22KHz tone to allow testing individual downconverters), but it can pass-thru the signals from a receiver and will let you see the LNB response to receiver control.
So, with the Accutrac connected to the old RCA, I saw between 190-220mA sourced from the receiver to the mux at the LNB feed. WIth the RCA disconnected and the Accutrac operating on its internal battery, the control voltages and currents were similar.
BUT, with the Accutrac connected in-line with the H20, it only showed 24-30mA sourced to the LNB mux. I also used the Accutrac from that same port to the LNB, but with the H20 disconnected, and the current it provided was on the order of 170-200mA.
I think that my H20 no longer can source enough current to get all the LNBs to switch polarization properly. Interestingly enough the 101 Sat seems quite happy with that 30mA, but the others just don't seem to switch properly.
I also looked at the DC resistance of each port to the LNB mux with no receivers connected, and I measured about 60Kohms at each one... so no DC shorts or opens are present in the system. Can't speak for the RF impedance of each one though -- the network analyzer is too big to "borrow" from work! 😉
Any additional thoughts from you guys, before I call DTV and ask them about H20 warranties?
Oh, one final note to greywolf. I reset the H20 several times during the course of the past few days, and when it no longer decided that it could see the 119 Sat transponders (as it did when it went thru power-on reset), it refused to include the Test Channels for anything except the 101 Sat in my channel guide. So, I couldn't use the Test channels to check any of the other Sat feeds from the LNB.
I'm asking for more comments from you all because I'm still not 100% convinced that this is a receiver problem. I noted this morning, since we have a clear and sunny day here today, that I have partly recovered some signal on those 119 odd transponders that were attenuated last night. Do I have a receiver problem here, or do I have a case where I have something funky with the LNB that causes it to draw more current when cold/damp than when warm and toasty? I am thinking that maybe the H20 simply has a current limiter in it which is preventing it from sourcing too much current in the event of a short on the line... that may not have been included in the old RCA design. I'm speculating here, mostly because I am an Electrical Engineer (and an old RF antennal guy) and I don'[t have the schematics here to really drive this issue to ground. I'm hoping that one of you guys have access to more detailed technical info than we do!
Thanks in advance for any help you can provide!
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