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all my even transponders have lost their signal  

post #1 of 10
Thread Starter 
Hi, can anyone solve this?

I have 2 DirecTV boxes: one NTSC and one HD (Hughes E86 via Philips brand). The transponder strength on the NTSC box is fine for every transponder. But on the HD box, on the 101 satellite, transponders 2, 4, 6, 8, etc. are either intermittent, or at zero; usually zero. I've unplugged the HD box and waited for 20 minutes. When I reacquire the pgm guide, all the transponders are there, but within hours or days, the even ones disappear again.

On another thread graywolf suggested I put in a fan. I did that, but the problem was not alleviated.

I have an old DTC-100; I substituted the box for the Hughes and found the problem is still there, so it's not the box.

The two differences between the connections on the two boxes: the NTSC one is one single piece of coax, from the dish to the splitter in the roof. The HD box is connected from the dish, to a roof-mounted preamp, where it's combined with the OTA antenna cable, and the combined cable goes across the roof; the cable wasn't long enough so I joined it to another cable, using a gold-plated cable connector. From there, it's into the attic until it gets to the splitter.

Thinking I had a loose connection, I've retightened every single connection probably 10 times. Occasionally, when I shake the cable in the attic, the transponders reappear for a few days, and then go away again.

I spoke to a sat repair guy, asking him if he thought I had a static electricity problem and he said no way that could be the problem.

Any ideas? I'm tired of going into the bedroom every time I want to watch HBO.

post #2 of 10
It sounds like bad equipment on the cable. Try switching places with the 2 boxes to check. The words "splitter" and "preamp" raise red flags. You also said combined but didn't mention diplexer. Splitters don't work with satellite cables for multiple boxes. Preamps are used for OTA antenna cables, not sat cables. You need to run a line directly from the dish to each box. The only device that you need would be diplexers if you wanted to combine the OTA antenna line with the sat line. Other devices could be blocking the 13V/18V DC signals the boxes send to the dish to select odd and even transponders.
post #3 of 10
Thread Starter 
To clarify: I should have said "diplexer" when I said "splitter." I'm using diplexers. I'll try switching boxes and see what I learn.
post #4 of 10
You could also check the signal without the diplexers. One of them may be bad. What connections get moved when you shake the cable?
post #5 of 10
Thread Starter 
That's an interesting idea. I presume, although I haven't yet checked it, that it is the cables to the HD box (and not the box itself) because two boxes fail to pick up the transponders.

So you can connect the cable, without "dediplexing" it, to the sat in line? Didn't realize you could do that. Thought it had to be separated from the OTA signal first.

When I shake the cable, I am shaking the cable within the attic that is attached to a gold coax connector (which lets you string 2 pieces of coax together) that is about 20 feet away, just outside the attic vent window, on the roof. That's why the connector is gold--I replaced the original one, thinking that might be the problem, and screwed it on very tightly.
post #6 of 10
Originally posted by Eric
So you can connect the cable, without "dediplexing" it, to the sat in line? Didn't realize you could do that. Thought it had to be separated from the OTA signal first.
I was talking about temporarily bypassing the diplexers altogether in case one is bad. On the subject though, the Hughes built boxes have built in diplexers at the Sat input. You can diplex your OTA and Sat cables together and feed the diplexed signal to the Sat input. Then go into the Installation/Local menu and select Antenna for the Local in 2 connection. If you were using 2 diplexers before, and if the box works right with no diplexers, figure one is bad and remove that from the mix. I'm still concerned about that preamp though. Assuming it is for OTA signals, it needs to be between the OTA antenna and the top diplexer. If it's in the path to the dish it could be blocking the 18VDC signal from the box to the dish that selects the even transponders.
post #7 of 10
I would have to agree with Greywolf this is definitly a voltage thing. Are you using the Sat boxes voltage to feed the preamp? I would guess that there is just not enough power. If you haven't already, disconnect the ant lead from the preamp and see if the even transponders come back. This will eliminate the preamp load on the STB power supply.

post #8 of 10
Thread Starter 
Wow--this may have worked. 12 hours ago, I disconnected the diplexer near the STB, and connected the single cable into the sat in input and chose "local in 2". I never realized that there was a built in diplexer. I should have read the manual more carefully.

Now, I have all my transponders, pushing 80-90s, (with two in the 60s).

Also, I don't know if it's my imagination, but the OTA signals that I do get (about 4) seem stronger; the signal strength seems up from before (I forgot to write down what I was getting before).

I'm hesitant to say that the problem is solved, as it's only been 12 hours. I'll report back in a few days.

FYI, the only reason I was using diplexers was to get the two cables (from the sat and the OTA antenna) into one, once they entered the attic; I had existing coax running through the walls and couldn't string a second cable to the TV. So the remaining diplexer is only used just before it connects to the coax in the wall. And yes, it does come after the signal preamp for the antenna; I was careful about that.

Anyway, thank you VERY much Greywolf, for your thoughtfulness and the time you've spent helping me.
post #9 of 10
Thread Starter 
Here's an update: after my last post stating that all the transponders were now coming in at a good level, the situation changed, so that the even transponders were again out.

However, over the past few weeks, they've all come back and seemingly stayed in a good condition; I've been running the fan on top of the STB, and switched out the diplexer in the attic, removing the diplexer next to the STB.

So who knows? Maybe the fan needed to run for several days to set the box back in a steady state. Maybe the box needed to reacquire something to put it back into equilibrium. And maybe the incredibly hot days we've had here in L.A. even overpowered the fan's ability to lower the STB's temperature.

Regardless, things seem fine--for now.
post #10 of 10
More likely one or both of the diplexers was causing a drop in the signal voltage below the threshold. A drop at the source isn't out of the question though. It's also important that the diplexer only allows DC to pass on the Sat leg. A picture at http://www.impactacoustics.com/produ...ource=overture clearly shows a power pass only on the Sat to common leg. Blocking DC on the other leg prevents the receiver from sending DC to the preamp and the preamp from sending DC to the dish/multiswitch.
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