etu Posted December 11, 2020 Report Share Posted December 11, 2020 We have a 2016 Keystone Cougar 5th wheel we bought in May and are still learning about certain details. Our last trip was first time we used heat and it worked fine. However when the furnace fan cuts on TV reception goes bad. Screen may freeze up or pic goes off altogether. That was on cable. When I got back home I tried it on antenna and same thing. Also happens when the bathroom vent fan is turned on. I had my local TV service man out and we traced all coaxial cables (and labeled them) and we put on all new crimp on terminals. We also tested all the cables with 75ohm test caps and we don't have any unusual resistance on any cables. Also tested the 12v power at the antenna switch with and without the fans on and we have 13.10-13.11V D.C. Im thinking I should replace the Wineguard antenna switch as next step. Any other ideas? Quote Link to comment Share on other sites More sharing options...
TXiceman Posted December 12, 2020 Report Share Posted December 12, 2020 Make sure the shield on all of the cables is connect at each termination. Worst comes to worse, they may need to put a trap or filter on the TV connection. Also start checking for loose grounds all over the 12 volt system, especially with the fan motor. Al alternate is to add a capacitor across the power to the power at the fan motor. This takes some experimenting. If you know a ham radio operator near by contact him some help. Ken Quote Amateur radio operator, 2023 Cougar 22MLS, 2022 F150 Lariat 4x4 Off Road, Sport trim <br />Travel with 1 miniature schnauzer, 1 standard schnauzer and one African Gray parrot Link to comment Share on other sites More sharing options...
etu Posted December 12, 2020 Author Report Share Posted December 12, 2020 Thanks Ken. Is the trap or filter something you put on the coax just before going into the Tv or is it before going into the Wineguard antenna switch? Quote Link to comment Share on other sites More sharing options...
Barbaraok Posted December 12, 2020 Report Share Posted December 12, 2020 If you were using cable, wasn’t the antenna switch off? Trying to understand how 12V systems are interfering with 120 volt TV. Quote Barb & Dave O'Keeffe 2002 Alpine 36 MDDS (Figment II), 2018 Ford C-Max HYBRID Blog: http://www.barbanddave.net SPK# 90761 FMCA #F337834 Link to comment Share on other sites More sharing options...
Jinx & Wayne Posted December 12, 2020 Report Share Posted December 12, 2020 5 hours ago, Barbaraok said: Trying to understand how 12V systems are interfering with 120 volt TV. It has nothing to do with the power source. The problem is interference with the signal coming into the TV, probably through the coaxial cable. My bet is on a bad ground causing a spark. A good spark can transmit radio frequencies on a lot of frequencies causing electromagnetic interference -EMI). When that happens wiring can act as an antenna. The coaxial cable used in TV's has a metal mesh outer layer that is supposed block this, but it isn't perfect. The TV tech was tracing coax and redoing connections to try to limit the EMI. Quote Jinx and Wayne 2006 Carriage Carri-Lite 36KSQ Link to comment Share on other sites More sharing options...
etu Posted December 12, 2020 Author Report Share Posted December 12, 2020 I have an idea. Next time I'm camping and have access to cable I think I'll hook the campground cable to my "satellite in" at the outside compartment and hook my Tv to the satellite output terminal at the entertainment center. Based on our tracing (and a Keystone schematic) the satellite in cable goes directly to the entertainment center. This would bypass the entire Wineguard switch and all the other related coax. If that is successful it would be one more reason to replace the Wineguard switch. Am I thinking correctly? Quote Link to comment Share on other sites More sharing options...
Kirk W Posted December 12, 2020 Report Share Posted December 12, 2020 15 hours ago, etu said: Im thinking I should replace the Wineguard antenna switch as next step. Any other ideas? I don't see how that switch could play any part in this since it is the two fans that cause the problem. Most motors do generate some rf energy but it usually doesn't affect the TV. You should have the antenna amp off when using cable anyway as that normally bypasses that amplifier. Testing cable with the satelliet input is a good way to try going around the TV antenna amplifier too. It also pass over any other potential problem areas in that system so if that solves the problem, it really isn't proof that the antenna amp is the problem. I am sure that they can fail, but I can't recall ever having seen that happen. Quote Good travelin !...............KirkFull-time 11+ years...... Now seasonal travelers.Kirk & Pam's Great RV Adventure Link to comment Share on other sites More sharing options...
Wrknrvr Posted December 12, 2020 Report Share Posted December 12, 2020 Just a odd thought on your situation. Do you have the batteries disconnected. Just running on the converter. That may cause problems. Always have the batteries connected. They remove stray alternating current from the 12vdc side. Next thing is all 12 vdc connections clean. Dio you have a twist lock connection on the power cord at the rv . I have seen the ground , that is the shiny metal on the side (50amp) cause problems with electronics Just thinking, Vern in a T-shirt Quote Link to comment Share on other sites More sharing options...
Wrknrvr Posted December 12, 2020 Report Share Posted December 12, 2020 Also years ago there was some problems with fluorescent lights causing some problems. I think like back around 2010 or 2012 timeframes. i need to take a history pill to clear that time frame. Vern in a T-shirt Quote Link to comment Share on other sites More sharing options...
Wrknrvr Posted December 12, 2020 Report Share Posted December 12, 2020 I had one situation where the ground on the shore power post was gone. When cable person disconnected the cable he got 110 vac shocked. Nothing serious but that pointed to a ground problem on the incoming power supply. Vern in a T-shirt Quote Link to comment Share on other sites More sharing options...
etu Posted December 12, 2020 Author Report Share Posted December 12, 2020 Great replies. Thanks. Yes battery is connected and shows 12.7 volts when the shore power is off. The problem occurs at home and at campsites so I don't think it is a shore power problem. Not sure how to test my 50 amp power cable on the camper end for ground but I'll look into that. With a previous camper I had an led light that created a similar problem but when I replaced that one light all was well. Thanks for all the input. Quote Link to comment Share on other sites More sharing options...
Kirk W Posted December 12, 2020 Report Share Posted December 12, 2020 21 minutes ago, Wrknrvr said: Also years ago there was some problems with fluorescent lights causing some problems. I have had that experience. I replaced an RV light with a cheap fluorescent light that created rf. It took me a while to figure it out but eventually discovered that I only had the problem when that light was on. 6 minutes ago, etu said: Not sure how to test my 50 amp power cable on the camper end for ground but I'll look into that. Just use an ohm meter and measure resistance from the ground pin of the plug to a good chassis ground location on the RV. It should be very near to 0 ohms. Quote Good travelin !...............KirkFull-time 11+ years...... Now seasonal travelers.Kirk & Pam's Great RV Adventure Link to comment Share on other sites More sharing options...
Wrknrvr Posted December 12, 2020 Report Share Posted December 12, 2020 This is where I have seen a ground problem. The shiny metal on the side is the ground on a 59 amp plug. Vern in a T-shirt Quote Link to comment Share on other sites More sharing options...
etu Posted December 12, 2020 Author Report Share Posted December 12, 2020 Ok so I just checked my 50 amp cable ground and it is fine when checked as Kirk suggested. While there I looked at the wiring going from the main body to the slideout and noticed the 2 coax cables going to the entertainment center is in a 5/8" corrugated wiring loom along with several 12v wires. just wondering if this is good ptactice? Quote Link to comment Share on other sites More sharing options...
Alie&Jim's Carrilite Posted December 12, 2020 Report Share Posted December 12, 2020 48 minutes ago, etu said: Ok so I just checked my 50 amp cable ground and it is fine when checked as Kirk suggested. While there I looked at the wiring going from the main body to the slideout and noticed the 2 coax cables going to the entertainment center is in a 5/8" corrugated wiring loom along with several 12v wires. just wondering if this is good ptactice? That can be the issue. The furnace fan runs on 12v, and your probably picking up interference. Quote Jim's Adventures Old Spacecraft.... Who knows whats next Link to comment Share on other sites More sharing options...
lenp Posted December 13, 2020 Report Share Posted December 13, 2020 Is there a chance you have a bad ground connection from battery negative to chassis? Clean all battery and ground connections for a start. You could also check your battery voltage at the load end (with a load) - say across a light that is turned on. A bad ground could/would drop significant voltage and cause all kinds of RFI issues Lenp Quote USN Retired 2002 Winnebago Ultimate Freedom 2012 F150 4x4 2018 Lincoln MKX 2019 HD Ultra Limited Link to comment Share on other sites More sharing options...
etu Posted December 13, 2020 Author Report Share Posted December 13, 2020 I've checked and cleaned the battery ground on the chassis. It looked fine. Please explain how to check the battery across a light. Quote Link to comment Share on other sites More sharing options...
lenp Posted December 14, 2020 Report Share Posted December 14, 2020 If you measure battery voltage across the battery you should read somewhere between 12.5 & 13.5 volts depending on the charge state. If there is a bad connection anywhere (chassis ground, battery terminals, bad cable, etc.) there WILL be some additional voltage drop across that bad connection. If all connections are in good condition you should measure nearly the same voltage at any load in the RV. Simply drop a light fixture from the ceiling (or any other place) and measure the voltage at the wires coming into the fixture with the light turned ON. It should be within a few tenths of a volt of what the batteries read across the battery terminals. Lenp Quote USN Retired 2002 Winnebago Ultimate Freedom 2012 F150 4x4 2018 Lincoln MKX 2019 HD Ultra Limited Link to comment Share on other sites More sharing options...
etu Posted December 15, 2020 Author Report Share Posted December 15, 2020 I understand now. Thanks. I'll check it and reply. Quote Link to comment Share on other sites More sharing options...
Wrknrvr Posted December 18, 2020 Report Share Posted December 18, 2020 Try unplugging the converter. There maybe a problem with it that is causing the problem. Just thinking, Vern in a T-shirt Quote Link to comment Share on other sites More sharing options...
etu Posted December 18, 2020 Author Report Share Posted December 18, 2020 I'll give that a try. Thanks Quote Link to comment Share on other sites More sharing options...
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