JVC LT-48C570 Suspect firmware

[6BW6]

JVC LT-48C570
One blink and the led goes out after about three seconds, all power lines up and running otherwise no sound and no screen.

LED backlights OK on external tester. I suspect firmware corruption..... can anyone help? Screen number is LSC480HN08.8

Thanks, Dave

[nomoresonys]

Re: JVC LT-48C570 Suspect firmware

Maybe start with testing the voltages at the connector on the powerboard with the cables all hooked up, it's the connector that the cable from powerboard to mainboard hooks into, most times there's a legend/map nearby that gives the expected voltages, you measure them with your mutimeter, set meter to 20 vdc then report them, put neg probe on chassis metal ground, pos probe on pin of connector, measure in standby take note, leave probes where they are then power on tv and again take note of voltages, report them here, example pin 1-ps-on-0 volts standby-power on-3.3 volts. Also good clear straight on pictures of each board and one of the whole back so we can see how they are connected, can upload by hitting go advance and manage attachments.

[6BW6]

Re: JVC LT-48C570 Suspect firmware

Thank you for the reply.
We are looking at CON201 on the power board-:

1) On bk = 0
2) 5V = 5V
3) on/off = 130mV
4) 5V sb = 5.09V
5) 5V = 4.74V
6) 5V = 5.09V
7) Gnd
8) Gnd
9) Gnd
10) 12V = 12.09V
11 12V = 12.09V

Oooops I've missed pin 1 the BL adjustment pin (this is zero)

On the main board The LVDS voltage is being generated this seems to go into the CPU then appears to come out and find it's way to the Tcon board fuse - there is 0V from here (maybe it isn't being switched).

I scoped them all and seemed 'ripple & hash free'.

Dave

[nomoresonys]

Re: JVC LT-48C570 Suspect firmware

Looks like the mainboard isn't sending the bl-on or the on/off signal, 130 mv is way too low.

[6BW6]

Re: JVC LT-48C570 Suspect firmware

Looks like the mainboard isn't sending the bl-on or the on/off signal, 130 mv is way too low.

Yep 130mV ain't going to do much.... funny thing is if you leave it in this ON state I noted the LED flashed once after a minute or so producing a click in the speakers. Whether it's CPU or firmware I'm not to sure.

I can't detect any voltage variations when I first switch it On, it may well be in a self protect mode, I've not studied the CPU yet..... be interested applying 1.5V to see what happens.

Dave

[Diah]

Re: JVC LT-48C570 Suspect firmware

JVC LT-48C570
One blink and the led goes out after about three seconds, all power lines up and running otherwise no sound and no screen.

LED backlights OK on external tester. I suspect firmware corruption..... can anyone help? Screen number is LSC480HN08.8

Thanks, Dave

i dont trust this tester... because even you have shorted one LED the rest will lit on... as you do the test while screen in place so you just make judgment with visual lit .

start script at any TV when turn on it send Power ON... and BL on at same time.. in about view ms time. so before you play with main boards.. set your voltmeter as 200-250 V DC and put the probe on any group of led socket + - and turn on you will find that you have voltage read as high then low... tell us what you got and post photo f the led socket.

[budm]

Re: JVC LT-48C570 Suspect firmware

Yep 130mV ain't going to do much.... funny thing is if you leave it in this ON state I noted the LED flashed once after a minute or so producing a click in the speakers. Whether it's CPU or firmware I'm not to sure.

I can't detect any voltage variations when I first switch it On, it may well be in a self protect mode, I've not studied the CPU yet..... be interested applying 1.5V to see what happens.

Dave

Are you talking about backlights LED flash on for seconds?
Keep meter probe on chassis and monitor BL-ADJ (PIN 1), and ON/OFF pin each time you turn on the TV to see how high the Voltage jumps up to before settling down.
There should be 3 control signal, you show only two signals: BL-ADJ, ON/OFF. There should also be PS-ON.
Show us good clear pictures of the whole backside of the TV so we can see how all the boards are connected together, also good clear straight shots of the power supply board and around the connectors so we can see the pin names of the connectors.

[6BW6]

Re: JVC LT-48C570 Suspect firmware

Re-: LED backlights, no not even a flash.

1) They work ok on an external tester
2) They work ok when 'ON bk' pin externally powered.

There is NO evidence of one or more LED/s backlight failure, it is clearly NOT a backlight issue.

Therefore I can only suspect either CPU or Firmware corruption AND to add to the fun the firmware is stored in the CPU since there is no EEPROM chip on board.

Just had word from JVC UK - it ain't one of their telly's....! These are made specially for Curry's & PC World, by Vestel no doubt, I fired a Email off to them as JVC UK suggested, I await their response but no help will be their reply.


Dave

[diif]

Re: JVC LT-48C570 Suspect firmware

A photo of your mainboard and/or sticker from the back of the TV would confirm but looking at the power supply on ebay it doesn't look to be made by Vestel.

[6BW6]

Re: JVC LT-48C570 Suspect firmware

Mainboard T.MS3546S.711.... sorry I don't think it's a Vestel as I said, more like a Chinese Shenzhen MTC product a good possibility.

Dave

[budm]

Re: JVC LT-48C570 Suspect firmware

Right now we do not even have the pictures of the boards to show us what we are dealing with.

[6BW6]

Re: JVC LT-48C570 Suspect firmware

Sorry thought the board number would suffice, here we are-:

https://ibb.co/LhPh6yP

Dave

[budm]

Re: JVC LT-48C570 Suspect firmware

Sorry thought the board number would suffice, here we are-:

C:\Users\David & Lilian\Documents\IMG1

?????
There are so many numbers we need to know about the board.
There is blank PCB part number.
There is PCB revision number.
There is PCBA part number.
There is PCBA revision part number.
And we can also see the condition of YOUR BOARDS and how solder joints and some condition of the components of your board if we can see the pictures of the board. So basically we need to see YOUR board.

[6BW6]

Re: JVC LT-48C570 Suspect firmware

https://ibb.co/LhPh6yP

[budm]

Re: JVC LT-48C570 Suspect firmware

That is only picture of the main board.
We need the pictures of the whole backside of the TV showing all the boards and how they are connected together, and also good clear straight shots of the whole board of each board so we can clearly read the prints and pin labels of the connectors.
Why don't you use attachment function (Use GO ADVANCE) to attach your pictures instead of using third party website.
It hard to do long distant troubleshooting when we do not have the TV in front of us to look at.
BTW, you do have proper tools to do repair, correct?

[6BW6]

Re: JVC LT-48C570 Suspect firmware

https://ibb.co/xGpkHVT I'll try a better one....!

[nomoresonys]

Re: JVC LT-48C570 Suspect firmware

You can not upload pictures here? Just click go advanced then manage attachments.

[budm]

Re: JVC LT-48C570 Suspect firmware

you can not upload pictures here? Just click go advanced then manage attachments.

+1

[budm]

Re: JVC LT-48C570 Suspect firmware

We need good clear straight shots of the boards, we also need the straight shots pictures of the bottom side of the power supply board so we can easily see the pin labels, parts designators, prints, traces, etc.