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Discussion Starter · #1 ·
Hey all,


I ordered a Channel Master CM 7777 unit from SolidSignal.com for use on my parents house in Mississippi. Dad and I installed it on an outdoor antenna (40 ft high) putting the amp right below the rotor. Power supply of course indoors. The cable run was about 50-60 ft total. Anyway once we hooked everything up according to the directions and tried it out, all the HDTV channels that they were sort of kind of getting completely dropped out. According to Solid Signal this is what happened " Its quite possible the amp is bad. ESPECIALLY if you unplug the power supply and you still get the same amount of channels. If an amp is not working then you will get an 80% reduced signal. So even on a working amp when you unplug it you lose most of your stations. If the amp didn't work then you would get a 80% reduced signal no matter if its plugged in or not. Based on this quick test I can deem this unit defective, and get a replacement underway." So we did the test and sure enough it was the amp (or at least we think).


My question is should we continue to stick with the CM 7777 or is their another system that would be better for my parents setup? I know there are probably some details I left out but I would appreciate any thoughts on this matter...
 

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Are you sure you hooked it up correctly? Amp has option of separate or combined VHF and UHF antenna inputs.


Could also be a problem with DC continuity between power supply and preamp or a bad power supply. Disconnect F connector at power supply and measure voltage. Then do the same at the preamp.
 

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Quote:
Originally Posted by msu12181 /forum/post/16960397


So any thoughts on whether or not I am overloading the amp based on the tvfool url I posted?

No TV overload. Did you try the FM trap set to "in"? I doubt it is the problem, but personally, I would see if it makes any difference.
 

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Discussion Starter · #10 ·
Yea when we first hooked the unit up, we followed the directions and left everything in its default factory setting (FM trap in, combined UHF/VHF). Seeing that this didn't work we called our local Radio Shack and they said it needed to be set to FM trap OUT. Tried that and still no luck.


We sent the unit back to SolidSignal and got a refund on the non working unit. My question is now - Do I take the chance that it was just a bad CM 7777 unit or do I need to consider another setup?
 

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Discussion Starter · #11 ·
By the way too, when I opened the pre amp box up to change these settings I noticed a strong odor like burnt electronics. However I didn't see any changes in the color of the solder or burn marks on the board itself.
 

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I have a question for other cm-7777 owners:

Does the 'preamp box' (the gray metal box that is mounted on the mast) run pretty hot?

As in too hot to hold a finger, much less an entire hand, on?

(I'm guesstimating that it must be 120+ degrees F on the metal casing if I can't even hold a hand on it for longer than 5 seconds!)


Is this normal for a CM7777 that is powered up, pre-amping 2 antennas?

(One homemade 2-bay VHF, and one homemade 4-bay for UHF?)

Oh yeah, the antennas and the preamp are in an attic.

(in Southeast Minnesota, so it shouldn't be too extremely hot in the attic.)


The operation of the CM7777 has been great for me, so it doesn't appear that anything has failed internally.


Sort of along the lines of msu's prior post....
 

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Discussion Starter · #13 ·

Quote:
Originally Posted by strudel.chris /forum/post/16961646


I have a question for other cm-7777 owners:

Does the 'preamp box' (the gray metal box that is mounted on the mast) run pretty hot?

As in too hot to hold a finger, much less an entire hand, on?

(I'm guesstimating that it must be 120+ degrees F on the metal casing if I can't even hold a hand on it for longer than 5 seconds!)


Is this normal for a CM7777 that is powered up, pre-amping 2 antennas?

(One homemade 2-bay VHF, and one homemade 4-bay for UHF?)

Oh yeah, the antennas and the preamp are in an attic.

(in Southeast Minnesota, so it shouldn't be too extremely hot in the attic.)


The operation of the CM7777 has been great for me, so it doesn't appear that anything has failed internally.


Sort of along the lines of msu's prior post....

I noticed it was getting that way on me when we were checking it out after the initial install. The preamp box was really hot, had to have a pair of work gloves on to handle it. Of course, I was on a metal roof in South MS in the middle of July too...
 

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Discussion Starter · #15 ·
What do you guys think about a Winegard AP 8275 Chromstar 2000 Series VHF/UHF Pre Amplifier for my situation given the TVFool results or should I stick with the CM7777? I have yet to order anything and I read that the Winegard has a circuit layout that virtually eliminates transistor burnout.
 

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Quote:
Originally Posted by msu12181 /forum/post/16964959


What do you guys think about a Winegard AP 8275 Chromstar 2000 Series VHF/UHF Pre Amplifier for my situation given the TVFool results or should I stick with the CM7777? I have yet to order anything and I read that the Winegard has a circuit layout that virtually eliminates transistor burnout.

I've never had a problem with a CM7777, except one I broke off a connector on, which was my fault. Just curious, did you notice what country your 7777 was assembled in?


The 8275 is "OK" but from your TVFool, I would stick with a lower-noise 7777.


Check all your connections and make sure it's connected like this:
 

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Quote:
Originally Posted by Digital Rules /forum/post/16960720


No TV overload. Did you try the FM trap set to "in"? I doubt it is the problem, but personally, I would see if it makes any difference.

There is a strong possibility of overload from WFFF-FM on 96.7. Run fmfool from your house to see the signal strength.


The advice from the Radio Shack clerk was wrong.


FM overload is more likely to occur with a 2-69 antenna, but not so much with a 7-69 or a UHF only. There is no reason to use a 2-69 antenna unless there is a channel 2-6 within range of your house.
 

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Quote:
Originally Posted by msu12181 /forum/post/16961752


I noticed it was getting that way on me when we were checking it out after the initial install. The preamp box was really hot, had to have a pair of work gloves on to handle it. Of course, I was on a metal roof in South MS in the middle of July too...

My CM7777 is cool to the touch, always. It is connected to an indoor antenna on the bedroom TV.
 

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Note: turrmoil is not the thread starter for this thread.

He has posted his question on an old thread because his problem is similar.


Hello, turrmoil:
Quote:
Do you guys think a CM7777 will help?
No, it will hurt because the preamp will be overloaded by WATC, which is only 1.1 mi away from you in Atlanta. Even without a preamp it might be strong enough to overload your tuner.


The only way you could use a preamp for your weak signals, if that is what you want, would be to insert a custom bandstop filter to attenuate WATC before the preamp.


What antenna are you using? Where is it located?


What channels do you want?
 
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