Headrest Tft Monitor Problem - Please Help

[ahmed24]

Hello everyone.

I am having a rather strange problem with one of my TFT headrest monitors. I have two headrest monitors on my Lexus IS250. Each of the monitor has a small sort of power regulating circuit board with a 2A transparant fuse. The monitors have been hardwired into the Cigarette Socket, and according to my lexus owners manual, the Cigarette Socket has a 15A fuse. The problem is as follows:

After starting up the monitors the one with the problem seems to work for around 5minutes or so and then just completely goes white with vertical lines. The other one however doesnt do that. I have tried to run just one at a time also tried both at the same time with no Luck. Once i get this white screen I have to either press the power button and power the screen off and back on or I have to press input source button to switch to the second input source and then come back to the input source. After this it works for a very little while and does the same thing over and over again.

I then tried to power the screen with a AC to DC adaptor that I have which provides 12V supply with 1.2A. When I run it of this plug it seems to run perfectly fine. But however if i plug it back into the car's supply it does the same thing over and over again. I replaced the 2A fuse that the small power regulator has with a 1.5A fuse but it still does the same thing.

Can anyone please advise me on possible solutions. I do not want to have to replace the screen as it is not under warranty or anything, bought it off eBay.

Would really appreciate any help

Thank you

[ukazn]

I had the same problem when I had my IS200. Maybe check your connections. Have you soldered the wires in. Sounds like its not getting enough power to the screen.

Might be a dodgy earth.

[ahmed24]

I had the same problem when I had my IS200. Maybe check your connections. Have you soldered the wires in. Sounds like its not getting enough power to the screen.

Might be a dodgy earth.

All the connections seem to be fine and they have all been soldered. I have also tried from different locations for the ground but still gives same problem. I also tried to use the connector from the working headrest with the faulty one and still the same problem. It seems to be coming only from that headrest.

any other possibilities? should I change the 1.5A fuse to something even lower maybe?

[Einstein]

Changing the fuse won't make any difference..

when you say you have swapped the leads over, I presume you are including the "regulator block" as well..

If you say it works fine from the mains adaptor... does this go through the regulator, or direct to the monitor..?

I can only assume either the regulator is faulty, or if you did swap them, more than likely it's the monitor itself..

As they are protected by a 2A fuse, they are drawing less than this.. and both together, less than 4A so the cigarette lighter socket should have enough capacity to cover both of them..

Another alternative is that although the monitor may be rated at 12V, it may have a very low threshold, and the voltage drop to the monitor brings it just below that threshold.. so if you can measure the voltage at the connector and post back.. it could help using heavy gauge wire direct from the Battery, to minimise the voltage drop.

John

[TigerFish]

Also, is it a problem with the engine running, or just when the engine is off?

[ahmed24]

thanks for your replies.

firstly, when i tried swapping to the other headrests wiring i did also swap the regulator but it still does the same thing.

when i tried it with the mains adaptor, it was also going through the regulator. The monitor actually only has one big cable coming out of it with a connector similiar to a S-Video connector, and the other side of the cable that comes from the regulator actually comes and connects to this connector.

John, when you say measure voltage at the connector, which connector are we talking about? connector from Cigarette Socket? i will measure the voltage that the Cigarette Socket gives me and also compare it to the voltage that my Mains socket adaptor gives me. Will post back results when i get home.

Oh and in regards to whether it is happening with engine on and off. I havent really tried it with engine off and on ACC. I have only tried it with the engine on. To try it with the engine off would mean I will need to run power with engine off for more than 5minutes, is that ok to do?

[Einstein]

Yes, I meant power from the socket... carry on :)

and with regards to the engine running, then this will give more power at the socket...

It's ok to run them with the engine off, but bear in mind it will flatten the Battery over time, and could cause a problem starting.

John

[ahmed24]

So, should I try to run the monitor with the engine off then? If i remember correctly the Main adaptor label says that output is 10 point something Volts DC and 1.2Amps. But if i remember correctly when i tested the output of the adaptor I did use to get around 11 point something Volts DC.

[TigerFish]

No need to do a test with the engine off mate. Only reason I asked was that you get a higher voltage on the car with the engine running. If you were getting the problems only with the engine off, it could've pointed to a dodgy Battery giving out a low voltage.

[ahmed24]

No need to do a test with the engine off mate. Only reason I asked was that you get a higher voltage on the car with the engine running. If you were getting the problems only with the engine off, it could've pointed to a dodgy battery giving out a low voltage.

Oh ok then. I will test the voltage output from my Cigarette Socket when i get home after work today and will also test the Mains adaptors Voltage output and post it here.

[Geoffers]

Tigerfish and John are leading you down the right road here.

It points to the internals of the monitor if you have swapped everything in the circuit and it works fine with an external adapter then the monitor is more sensitive to the voltage than the other. Confirmed more by the other monitor being fine and different power source.

I suspect the inline regulator is one of the usual fuse/filter units rather than an actual voltage regulator. Most voltage regulators are internal to the monitors.

Undervoltage from the car. I doubt it is this, but it may be failing below the threshold of the power circuit. Some regulators need a good .5+ of a volt over the working voltage to function correctly. E.g. If it is a 12v regulator then it will need 12.5v or more to work. A dodgy regulator may require more. It could be that voltage is low or the regulator itself isn't responding well.

Overvoltage from the car - If the output of the alternator is a little high, the monitors internal regulation will be under more stress. Maybe it is a little sensitive to this.

Dirty power. Tigerfish and John have probably done this already but if you were to look at the 12v line on the Lexus on a scope, it is fluctuating with all sorts of rubbish on it. (As with all cars). A decent regulator and caps usually sort this.

The monitor should cope with all these because it is the environment they are built for, but yours isn't for some reason.

Judging by what you have said already, I think you may need to put your own regulation circuit together or try a car audio outlet as they should have stabilisers and DC-DC converters.

They aren't Eonon monitors are they? I've had similar - even from the same batch they act differently.

[ahmed24]

Geoffers, thanks for your reply.

From what I can make of it so far, it seems like maybe its overvoltage or possibly the diry power thing about fluctuations in power. The mains adaptor that i have has a label on it that says that the output is 10 point something Volts DC and 1.2A. This is why I am thinking maybe it is issue with overvoltage because the car gives me 12v and above. I will run a test on my Mains adaptor later today and see if the power on that flactuates and will also do the same with the power from the cigarette socket. Will post results today.

Also in regards to the dirty power issue. I suppose the test should make it clear if car power is fluctating compared to mains power. If power is fluctuating, how can I bring it in line to provide a stable power to the headrest?

Oh and I am not sure if it is an Eonon monitor as it doesnt even seem to have a brand name on the box or anywhere in the usermanual nor the unit. Its just refered to as a 9" TFT monitor.

thank you all very much for your assistance in this. very much appreciated

[Einstein]

As they are both wired to the same power outlet, it seems fairly obvious one monitor is partially faulty...

I say partially, as it works on a mains adaptor..

The monitors "should" work fine on anything between say 11-14V, so my guess is the internal regulator circuit is not working as it should..

and as with most modern devices, they tend to use surface mounted miniature components, which are sometimes difficult to source, as well as replace.

John

[ahmed24]

I am just wondering, would it be possible to maybe buy some sort of additional power regulator circuit and then hook up the power from the car thats coming to the headrest to this circuit and have the circuit regulate the power (e.g. get the circuit to produce exactly the same results as my mains adaptor does) and the from this circuit provide power back to the headrest. This way the headrest will get a steady and regulated power.

[Einstein]

Although possible in theory, I can't say for definite without looking at the schematics for the monitor.. having no brand name doesn't help..

John

[ahmed24]

Although possible in theory, I can't say for definite without looking at the schematics for the monitor.. having no brand name doesn't help..

John

oh, i'll post the results of voltage test later this evening. hopefully that might help a little to diagnose problem.

[cholah]

I think I know what the problem is. I have had a similar problem in my GT4. One of the outputs from the DVD player was for the front monitor. This will not work unless the engine is not running. The idea is to stop you from watching while driving. I solved my problem by earthing the wire on the player that says handbrake (attaching the 'handbrake wire' on the player to the body of the car). Since then it all worked fine. This was an after market sony indash dvd player. Hope that helps. ta

[ahmed24]

I think I know what the problem is. I have had a similar problem in my GT4. One of the outputs from the DVD player was for the front monitor. This will not work unless the engine is not running. The idea is to stop you from watching while driving. I solved my problem by earthing the wire on the player that says handbrake (attaching the 'handbrake wire' on the player to the body of the car). Since then it all worked fine. This was an after market sony indash dvd player. Hope that helps. ta

Hi cholah,

Thanks for your reply. I do not think it is actually related to the input because my screen actually also does the same thing even if i do not have any input source. If i put it to an input source that hasnt got input, it says No Signal and then does exactly the same thing over and over again. So therefore it doesnt matter where the input source is coming from. Plus it happens even if the car is not moving

[ahmed24]

Just wondering if after running voltage tests i realise that the cars power fluctuates alot compared to the mains adaptor, then could i maybe get something like the following DC-DC converter to try and regulate the power before supplying it to the headrest?

eBay link: http://cgi.ebay.com/2-Way-3-Amps-Step-Down...1QQcmdZViewItem

[Einstein]

Something like that will give a regulated 12V output, but bear in mind it's a dual output.. 2 X 1.5A so you could use it to power both monitors.. one to each output.

It's not easy to diagnose this problem, but my gut feeling is a faulty monitor..

John

[ahmed24]

ok i've done the voltage test on both the car and the mains adaptor. from the car as soon as I start the car i get 13.9/14v and it fluctuates constantly between 13.9 and 14. If i rev the engine in the car then i sometimes get a much lower output and it went down to as low as 12.6. But if I am not reving then i get this 13.9/14 fluctuation.

On the other hand on my Mains power adaptor, as soon as i plug it in i get a reading of 13.6V and it very very slowly climbs up to about 13.8 and sometimes goes to 13.9 but back down to 13.8. But the changes on the mains adaptor is much more slow and gradual.

Any suggestions guys?

I know it is most definately the faulty monitor, but i want to try and somehow sort the problem by purchasing small circuit or whatever is needed at a cheaper price rather than having to replace my headrest set which is rather expensive.

Really appreciate all the help.

Thank you.

[ahmed24]

any suggestions? should i try getting that eBay DC-DC converter and try to maybe regulate a lower voltage to the device?

[Geoffers]

You are in a difficult position again here as you aren't exactly sure what the tolerances of the monitor are.

Yes, normally I would suggest a DC-DC converter but are you sure the monitor will work at exactly 12v stabilised?

Are there any car audio outlets in your area? Or any Electronic shops? Or do you have a stabilised 12v supply (other than the adapter you are using)? Just to see if it will work at that voltage. If it is fine at the 12v then go for that inverter.

Either way, it is a always a good idea to have a nice clean supply. I would look at getting one anyway. It may not help with this particular problem though.

As we a fairly certain it is the monitor itself, you need to bear in mind that if it has gone faulty this way, working around it may only be a short term solution and next week/month/year you'll find yourself in the same situation.

I don't mean to keep giving you negatives, I just wouldn't like you to be disappointed and a bit out of pocket.

I have to suggest getting a new monitor but I understand you want to do something with this one.

Ok, this is a bit extreme but you could solve it right now for £20. Nip to the nearest Maplins and pick up an inverter. Tell them you are going to test it in your car for 20 mins. Plug your mains adapter into it. My local one is always ok with things like that but they've got to know me now. (Maplins is like a sweetshop to me :D ).

Its a bit of a messy solution but for £20 it may be the answer. It would fit under the seat. This one is 100w so it should be fine even for a badly efficient 1.2a@12v. Just don't be tempted to plug a kettle in! When you are satisfied, just hardwire it in instead of plugging into the lighter socket.

You could even go a stage further and get a larger inverter and you could plug your games consoles and the likes in then too and feed to the monitors.

MAPLINS LINK

[ahmed24]

Thanks for your reply Geoffers. I think maybe the inverter option would probably have to be last resort as I really do not want to have to store an inverter in the car. Anyway, I am thinking of getting that DC-DC converter but just thinking it will end up taking over 2weeks to come as it is from China. Could you advise me if the following one would be ok instead: http://cgi.ebay.co.uk/ws/eBayISAPI.dll?Vie...em=200201048852

This one is from UK so hopefully I can get it sooner

[Geoffers]

Yep - that will do fine. Not a bad price either actually.

Any chance you could check that the monitor is ok on 12v? Just thinking if the regulator threshold is a bit on the high side, it may not work correctly.