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-   -   No signal; preamp needs replacing? (http://forum.tvfool.com/showthread.php?t=16767)

KevinTMC 29-Jun-2020 5:31 PM

No signal; preamp needs replacing?
 
Back in the fall of 2014, the good folks of this forum helped me get together an antenna (HBU44) and pre-amp (TVPRAMP-1R) setup that has provided excellent service...

...up until one day earlier this year, when I went to turn on the television and there was no signal--zero trace of anything on any channel.

(I'd meant to deal with this problem a bit more promptly, but this has been a crazy time.)

I suspect that the pre-amp has finally given out...which would be understandable, as it's been five years and change, a real good run for that inexpensive unit.

I would very much appreciate a little guidance as to:

a) Should I do any particular testing or investigation before going ahead and ordering a new pre-amp?

b) Should I just order the same unit again (looks like it is still on Amazon, but for $10 more than I paid last time) or consider getting something different?

Thanks again to the members of this forum for the previous help, and for still being here in 2020.

(Prior thread is here, in case it is of any help: http://forum.tvfool.com/showthread.php?p=45950)

Tim 30-Jun-2020 2:19 AM

Quote:

Originally Posted by KevinTMC (Post 63027)

I would very much appreciate a little guidance as to:

a) Should I do any particular testing or investigation before going ahead and ordering a new pre-amp?

Have you checked the output of the power supply with a voltmeter to make sure it hasn't failed? (The expected DC voltage should imprinted on the power supply.)

KevinTMC 10-Oct-2020 8:02 PM

Thanks for the reply. It's been a minute (continues to be a strange and difficult year), but I finally got round to borrowing a voltmeter and checking it out.

The meter reads 18VDC being sent down the coax pin...which is curious, since what's printed on the brick is 12VDC 100mA.

OTAFAN 10-Oct-2020 9:28 PM

Probably you're overloading your TV tuner with a defective pre-amp; something's failed (open) inside. You'll need to replace it.

You should be able to return to good TV viewing once fixed. Please let the forum know how it goes.

All the best.....

KevinTMC 11-Oct-2020 12:23 AM

If a resistor went out on the power supply at some point and started feeding the pre-amp with too much power, that would have hastened its demise at least...but this RCA TVPRAMP provided me over five years of good service (and for $24 too), which isn't bad in any circumstance...particularly as I ran across plenty of anecdotes about them dying within two years, back when I was shopping for the setup.

The listing Amazon takes me to if I want to re-order the same is here, and the price is currently $29.54:

https://www.amazon.com/RCA-TVPRAMP1Z...dp/B003P92D9Y/

Any thoughts on whether getting that again seems wise, or whether I should look at alternatives like the Winegard LNA-200?

OTAFAN 11-Oct-2020 4:58 AM

If you're handy with a soldering iron and have at least a hobbyist background on electronics, you could try to "fix" your preamp, if that's indeed what's wrong with it. If you do a search on TV Fool, you should be able to find some good, clear photos of inside your preamp. I think rabbit73 posted some a while back. If I can find them, I'll post it here.

Otherwise, I would recommend you read through this thread before you buy another RCA preamp, due to quality control issues this model has had. You were lucky to get a good, trouble free one for the five year life it gave you.

http://forum.tvfool.com/showthread.php?t=16768

Anyway, KevinTMC, just my two cents worth. I'm sure you'll come up with a solution that will work for you.

KevinTMC 11-Oct-2020 2:48 PM

Oh, the Kitztech looks like just the ticket. Costs more...but not exorbitant, and looks well worth it. I especially like the weatherproof enclosure, promising excellent protection while requiring no DIY skills from me more advanced than bolting it to the mast.

Looks like the KT-700 is newest and shiniest, but since my HBU44 is a single-antenna setup, I'm sure the KT-200 would do just fine (at $10 less...and maybe slightly higher confidence of longevity, as it's simpler and has a longer track record?).

Thanks again. Looking forward to having broadcast service again before much more of the football season slips by.

KevinTMC 17-Oct-2020 6:13 PM

Well, rats.

I settled on the KT-700, as there is a cell tower pretty close by. It arrived in the mail; I went up on the roof today to get it hooked up. Connected the coax in the proper places, added a bunch of electrical tape to help protect connections and gaps in the case, got it lashed to the mast, hooked up the inside bits, and...

...no signal still. At all.

I visually inspected the coax run and didn't see any damage or problems...but perhaps I need to get a meter to check it out properly? The issue must lie with either the coax or the antenna itself I would think.

(I would be sore about the possibility that I replaced the RCA unnecessarily, as I don't exactly have extra money sloshing around...but we've now passed that unit's sixth anniversary. Surely the upgrade to the Kitztech was going to be happening sooner rather than later anyhow?)

UPDATE: Went testing the coax run with a multimeter; think I may have found a bad section. Will replace and see if that resolves it. If not, the coax cable from the antenna to the preamp may also need replacing; the weather boot is falling apart, and the wire came much too easily out of the F connector as I was removing electrical tape and disconnecting.

rabbit73 18-Oct-2020 12:28 AM

3 Attachment(s)
To check the RCA, you have to make some voltage measurements.

First you check the voltage coming out of the power inserter without the preamp connected:

http://forum.tvfool.com/attachment.p...2&d=1602980232

Next, you check the voltage at the upper end of the coax without the preamp connected:

http://forum.tvfool.com/attachment.p...3&d=1602980271

Then you check the voltage to the preamp with the preamp connected. This is a little more difficult, because you need access to the coax center conductor when the preamp is connected. I use a T-adapter:

http://forum.tvfool.com/attachment.p...8&d=1511635684

http://forum.tvfool.com/attachment.p...4&d=1602980514

KevinTMC 18-Oct-2020 12:49 AM

I checked the voltage along the coax, section by section...found a stretch of cable and connector that looked like they'd gone bad. Replaced them and I've got signal!

Performance of the Kitztech unit is clearly stronger than the old RCA, and longevity would surely be much superior even if they were both new; I'll enjoy having it whether or not the RCA has actually completely died as I had thought.

Will go back up one of the next two Saturdays to do some more weatherproofing (rubber boots for connections if I can find some online, and more electrical tape and duct tape lots of places), and replace a couple more bits of cable and connectors that are older and/or longer than they need to be. With luck, I'll then be set for at least another 5 years.

Thanks again for the helpful advice here.

Tower Guy 18-Oct-2020 5:13 PM

Quote:

Originally Posted by KevinTMC (Post 63320)
Will go back up one of the next two Saturdays to do some more weatherproofing (rubber boots for connections if I can find some online, and more electrical tape

I’d suggest “stretch and seal” or similar tape. It sticks to itself and water can’t get in.

Duct tape can be porous.

jkeldo 27-Oct-2020 7:32 PM

2 Attachment(s)
Quote:

Originally Posted by KevinTMC (Post 63286)
If a resistor went out on the power supply at some point and started feeding the pre-amp with too much power, that would have hastened its demise at least...but this RCA TVPRAMP provided me over five years of good service (and for $24 too), which isn't bad in any circumstance...particularly as I ran across plenty of anecdotes about them dying within two years, back when I was shopping for the setup.

The listing Amazon takes me to if I want to re-order the same is here, and the price is currently $29.54:

https://www.amazon.com/RCA-TVPRAMP1Z...dp/B003P92D9Y/

Any thoughts on whether getting that again seems wise, or whether I should look at alternatives like the Winegard LNA-200?

Keep in mind that the new version of the RCA preamp only has a single input so if you need the separate VHF and UHF inputs, the one on Amazon your link specifiies is probably not the one as it has a 2 before the E where the other model had a 1 before the E only. Here are two pics of one I purchased about a year ago from Menards that had a barcode of 044476071669. Lowes used to also have this model but probably has the new one now.

Tim 2-Nov-2020 12:49 AM

1 Attachment(s)
Quote:

Originally Posted by Tower Guy (Post 63323)
I’d suggest “stretch and seal” or similar tape. It sticks to itself and water can’t get in.

Duct tape can be porous.

I'll second that suggestion. Electrical tape and duct tape are absolutely useless to seal antenna and coax connections. The self-fusing silicone tape is great and will keeps connections clean and dry for years. One commonly found brand is Nashua Stretch & Seal. You can usually find it at your local orange big box home improvement store.


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