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Post by quaysider on Mar 7, 2021 8:07:46 GMT
Strange thing occurred last night .
I'd turned the boat around to varnish the port hatches - as such, the tv ariel was pointing 'the wrong way'...
Having started to watch the thing on Harry and Megan (9pm on channel 5) the picture was driving me mad so I went out to spin the Ariel.
It made no difference.
I then "wiggled the coax" cable on the side of the telly, only to find it hot/melty. That threw me. First thought was the amplifier in the cupboard had gone belly up. Checked there - no sign of any heat and all well (other 2 tvs working fine).
On checking with my multimeter, there was a fluctuating voltage between 5 and 6 showing on the lounge (new batter powered) tv... the one I had the faff with a few weeks ago.
It's worked fine since getting the right charger and I was pleased with the viewing time on the battery.
Can anyone think of any logical reason why there might be /should be? 6 volts showing on the Ariel socket?- I'm guessing it's something to do with the usb wiring and tbh, I really can't face another faff with amazon to return the thing and get the balance of money back... I'm just going to take it apart and try and look for something obvious - IF I can see the problem, I'll solder a couple of wires on to each speaker to create a soeckt for the soundbar to attach to (despite it saying it has headphone out - it doesn't)...
This tv is turning into the Cello equivalent of a "Friday afternoon Allergo vanden plas" my parents bought many, many moons ago!
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Post by Gone on Mar 7, 2021 8:50:49 GMT
Strange thing occurred last night . I'd turned the boat around to varnish the port hatches - as such, the tv ariel was pointing 'the wrong way'... Having started to watch the thing on Harry and Megan (9pm on channel 5) the picture was driving me mad so I went out to spin the Ariel. It made no difference. I then "wiggled the coax" cable on the side of the telly, only to find it hot/melty. That threw me. First though was the amplifier in the cupboard had gone belly up. Checked there - no sign of any heat and all well (other 2 tvs working fine). On checking with my multimeter, there was a fluctuating voltage between 5 and 6 showing on he lounge (new batter powered) tv... the one I had the faff with a few weeks ago. It's worked fine since getting the right charger and I was pleased with the viewing time on the battery. Can anyone think of any logical reason why there might be /should be? 6 volts showing on the Ariel socket?- I'm guessing it's something to do with the usb wiring and tbh, I really can't face another faff with amazon to return the thing and get the balance of money back... I'm just going to take it apart and try and look for something obvious - IF I can see the problem, I'll solder a couple of wires on to each speaker to create a soeckt for the soundbar to attach to (despite it saying it has headphone out - it doesn't)... This tv is turning into the Cello equivalent of a "Friday afternoon Allergo vanden plas" my parents bought many, many moons ago! Just my random thoughts based on limited knowledge of your boat wiring Some TV sets have an option in the set up menu to output a low voltage on the antenna connection to power a mast head amplifier. So that could account for the low volts you found. However it is limited to 50 to 100mA so nothing like enough power to heat a coax cable. Depending on aerial type and TV type the coax cable might have the outer braid earthed via the aerial to the aerial mast and hence the boat hull and at the other end might connect the TV negative power supply to the coax for shielding, assuming you are using a non-isolated 12v stabiliser to power the set, this could act as an Earth return from that end of the boat back to your batteries via the coax braid and hull. I would put a clamp meter around the coax and measure the DC current, should be tiny or nothing. If there is a significant current then you need a braid breaker in your antenna coax cable. Added x something like this. www.amazon.co.uk/Axing-TZU-10-01-eliminator-F-Connectors-0/dp/B002MQJQG4/ref=sr_1_3?dchild=1&keywords=Ground+loop+isolator+f&qid=1615107733&sr=8-3Of course you may not be able to power a mast head amp through this, but then again you might depending on how it is all configured. It is worth sorting this problem, as if you do have an unwanted Earth return via the coax cable you will be putting a current into your hull - think galvanic corrosion, and if the current becomes big enough think very hot (fire risk) cable. However this is all worst case, maybe not applicable to you. another thought - when measuring the current in the coax you need to do this many times over a day or so to ensure you measure it when the offending item is drawing enough current to create a volt drop big enough to cause a current to flow in your coax cable. Hopefully all the above does not apply to your boat, in which case, sorry if I have alarmed you.
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Post by quaysider on Mar 7, 2021 9:14:17 GMT
That makes sense but I Can't find anything in the tv menus (the instruction booklet that came with it was actually for a different telly too) - there is nothing showing from the coax cable (I've checked all 3 tvs) . When I unplug the tv from the 19 v dc supply (either from the boats 12v or mains adaptor) and it's running on batteries, it STILL shows the reading. It has to be coming from the usb doesn't it? - I can only presume it's been like that since inception as as I tend to watch Netflix via chrome cast on the hdmi, I'd not spotted the heating up on the Ariel short. I'm having a bit of a change of heart now re- taking it apart... it's going back I think - may as well just buy a new one and chalk this dalliance into 'internal battery' tvs down to experience. Shame really as having "stored 6.6ah" of solar during the day for use on a night made really good sense.
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Post by Deleted on Mar 7, 2021 9:24:19 GMT
It's a shame you have had problems with the TV, I have the same make/model and have had no problems at all and love the internal battery usage (mine even has an audio out). Any point in contacting Cello and see if they would replace yours?
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Post by Telemachus on Mar 7, 2021 10:03:12 GMT
I suspect the two things are unrelated: Yes the 5v on the aerial socket may be phantom power for a booster, but not enough current to get things hot. An earth (battery negative) connection to hull via the coax cable allowing an alternative current path back to the batteries for services would explain the heating, but not related to the first point.
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Post by quaysider on Mar 7, 2021 10:07:18 GMT
You're right it is a shame... perhaps this one really was a Friday night lemon. the idea is great.... I'm guessing it was one of the first produced, cause the 12 to 19v power supply I bought from cello so I didn't have to charge it from the 230 to 19 v (which cello sent me free) had an anderson type connector on it rather than the circular one - ergo, I had to bastardize the old 12 one for it to fit.
I think I'll wait a couple more years and then try again - meanwhile, tv village sells the old 19inch combi unit inc delivery cheaper than i can find on ebay and amazon so I'll have one of those.
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Post by quaysider on Mar 7, 2021 10:12:37 GMT
I suspect the two things are unrelated: Yes the 5v on the aerial socket may be phantom power for a booster, but not enough current to get things hot. An earth (battery negative) connection to hull via the coax cable allowing an alternative current path back to the batteries for services would explain the heating, but not related to the first point. i don't understand this - all 3 sockets are connected into the same 'box' that comes from the amplifier - this one is the midships one but the other 2 don't get melty when plugged into their tvs?
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Post by Deleted on Mar 7, 2021 10:16:00 GMT
Just to say, I've checked my aerial socket and it shows 0 volts.
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Post by Deleted on Mar 7, 2021 15:19:16 GMT
Just be happy you don't have lizards in your telly.
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Post by quaysider on Mar 8, 2021 8:59:53 GMT
On further investigation, I think I understand Telemachus's point.
The output can be to power an amplified Ariel (which it might have come with but I binned)... I think (given I've just binned the thing anyway and written off the refund ) I'll nip to screwfix and replace the Ariel and wiring to the amp box... it's done 3 years now so owes me nothing and the bracket is looking a bit rusty.
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Post by Telemachus on Mar 8, 2021 9:35:23 GMT
On further investigation, I think I understand Telemachus's point. The output can be to power an amplified Ariel (which it might have come with but I binned)... I think (given I've just binned the thing anyway and written off the refund ) I'll nip to screwfix and replace the Ariel and wiring to the amp box... it's done 3 years now so owes me nothing and the bracket is looking a bit rusty. It is often the case that an aerial designed eg for a car, connects supply negative to hull via coax screen, so it may not be a fault. The way around it is to insert a small capacitor, say 10nF, in series with the coax screen thus allowing the rf through, but blocking any DC.
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Post by JohnV on Mar 9, 2021 8:00:26 GMT
I think it was Labgear used to sell a UHF 75 ohm isolating balun which would also do the job ..... However Telemachus capacitor method should work
With either method a certain insertion loss will occur but if it is done neatly with minimum lead lengths it shouldn't be too high.
It is possible to make your own UHF balun but you would need a fine pointed soldering iron and small needle nosed pliers and side cutters. If you want to try I'll tell more
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Post by quaysider on Mar 9, 2021 19:19:40 GMT
so I've Just googled how to make a balun and I'm none the wiser...
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