wow!2007 jvc lt-42e488 bad caps!

[kc8adu]

2 nippon chemicon kmq starting to bulge.
bought this set real cheap with an inverter issue and found this once i opened it.
btw to anyone who opens up a jvc set you MUST! cover the light sensor on the board.
looks like a led with a foam gasket around it.
it is there to erase the eeprom if you run it open. yes a fucking boobytrap!
i glopped it with jbweld.

[Krankshaft]

Re: wow!2007 jvc lt-42e488 bad caps!

Rumor has it that JVC uses this to protect their software from being stolen.

Although any 5 year old with a piece of duct tape who knew about this ahead of time could defeat it . Grey Epoxy putty works great too.

Why don't these old farts tirelessly trying to protect their content just give up already? It doesn't matter how perfect your protection is. If you release it to the public IT WILL be broken. The more obstacles you put in peoples way to harder they will work to break through those obstacles.

That's how I tick anyways .

Geez what's next exploding TVs when you open them? The ICs will smoke from overvoltage and the PCB will catch fire .

The only way to fix this if you muck up is to send the board to JVC (that's a trip to Japan) to get the EEPROM reflashed.

Here is an intertesting bit Panasonic owns JVC I never knew that.

[Krankshaft]

Re: wow!2007 jvc lt-42e488 bad caps!

The sensor is probably a photo transistor when it detects light it conducts.

They are available in 5mm LED packages I used one to make a homemade IR remote tester.

I must say though I hate when manufacturers plant "trip wire" in their products.

[kc8adu]

Re: wow!2007 jvc lt-42e488 bad caps!

time to do a dump and file it away for the day a hapless customer comes in with one after they sprung the trap...

[Wizard]

Re: wow!2007 jvc lt-42e488 bad caps!

Working in TV shop I'll add:

Pioneer uses trip switch thing too. :P

And I'm aware of JVC eye sensors for sucide style eeprom. I simply cover it like u did.

Cheers, Wizard

[cadillacman]

Re: wow!2007 jvc lt-42e488 bad caps!

bump to an old thread...


GREATTTTTT

i got one of these in a bulk buy...

story goes it was totally dead. The guy opened it, replaced the power supply( the original came.from.the.factory WITHOUT a heat sink on the rectifier!!!!

I will guarantee you he powered it with the back off..

i think ita a boobytrap victim..

When plugged in and powered on you hear the relays click, backlight kicks on, backlights shut back off and the led blinks green forever..


any way to fix this now or am i effed?

ooh wait i still have the old supply

i wonder if the old eeprom is still ok? one way to find out i suppose. Is thios prom on the mainboard or the power supply? if its on the pow supply i could swap it, if its on the mainhoard im so effed.

[cadillacman]

Re: wow!2007 jvc lt-42e488 bad caps!

( ok i have covered that stupid sensor.. thank god i saw this...

if i unplug the inverter board, the tv will power on and light stays on solid. As soon as the inverter board is plugged in, light starts blinking and tv shuts down

do you think i got lucky and have an inverter board issue, or is the fact its unplugged just stopping the powerup proce

EDIT: AHA!!! with the inverter board unplugged, not only does the led stay solid on, i have audio too!! so shes powering on at least most of the way!!!!!!


so, inverter board issue? ive been over it i cant find any bad fuses or shorted transistors, read lots of stories of bad transformers, but im unsure how to test these.

[cadillacman]

Re: wow!2007 jvc lt-42e488 bad caps!

hey when im checking those bigger tranaistors what value shouldd i have? and am i checking between the center and right pin?

[cadillacman]

Re: wow!2007 jvc lt-42e488 bad caps!

fast foward to today, good a "good" inverter board from a reputable seller, install... and..... same lol..

one thing i didnt notice before is a "hot" smell yet none of the components on the power supply or inverter board are running hot.

same thing. runs fine with inverter board disconnected, all inverter board fuses and xistors check ok, at this point i suspect one or more bad ccfls... and when i find anf xit that ill have a pile of good boards most likely lol

[cadillacman]

Re: wow!2007 jvc lt-42e488 bad caps!

good lord i cannot type very well...

*edit:
"same thing. runs fine with the inverter board disconnected, all inverter board fuses and xistors check ok, at this point i suspect one or more bad ccfls...

When i find the issue i suspect i will have a pile of good boards most likely lol

i REALLLY need to make a ccfl tester.. i just dont know how.

[cadillacman]

Re: wow!2007 jvc lt-42e488 bad caps!

bueller? buuuuuuuler?

[cadillacman]

Re: wow!2007 jvc lt-42e488 bad caps!

well i tore it down to the lamps and....... none look bad lol..

i also made a ghetto-fied ccfl tester out of my pachinko machine. It has some compact flourescents on it so i made some test leads out of dmm leads.

for some reason i can only get about half of the lamp to light, but they all light like that. at this point i dont think ccfls are my issue. I think im pretty much stuck without another tv to test parts with.
______________________________________________________________

So to recap i got this tv already monkeyed with. Used power supply and mainboard were installed by the former owner.. I saw this posting before i messed with it(thank god) so i did cover the sensor on the mainboard. The inverter board was already laying loose in the tv plugged in but not screwed down. I poured over the board looking for a shorted xistor or bad fuse. none found.

When powered on it shuts back down after blinking the backlights once or twice. Unplugging the inverter board will allow the tv to power up and stay on, it makes sound with input so mainboard is assumed at least partially functioning as well as power supply.

Bought and installed used inverter board from a vizio( same exact part #'s on board)

Installed the used inverter board and same issue. Except now i smell a "hot" smell after it flashes the ccfls and shuts down.

set still runs fine if inverter board is left unhooked.


im stuck at this point.. going to test a couple obious things then put it back togther to save for another day... so mad i cant get this figured out.

[cadillacman]

Re: wow!2007 jvc lt-42e488 bad caps!

ok its back togther..

for giggles i smelled around after shut down.. hot smell is in the area of the large transformer. both power supplies i have both do the same thing with the inverter unhooked stays powered on no smell..

plug in inverter board and shuts down after firing the ccfls, smell is back

i did replacee the main filter caps on the replacement power supply because on both sets they seemes to be slightly bulged. Replacing made no difference

[cadillacman]

Re: wow!2007 jvc lt-42e488 bad caps!

ok theres a thermister th9001 on the power supply, this is what gets hot and is making the smell. What would cause this? it only seems to get hot oncwe the inverters kick in and shut back off.. if its normal due to the inverter br issues then ill stop chasing it, but mabye that thermister is bad on both supplies i have?

i did replace the 4 filter caps that power the inverter along with some smaller ones in that ares( just for gigs) and no change same damn thing.. what the hell is going on with this thing?

[cadillacman]

Re: wow!2007 jvc lt-42e488 bad caps!

Bieng im on my own on this one, im going to have to shelf it for now. I cant afford to throw any more expensive darts at it lol..

I do see that my replacement inverter board has some different "solder pad jumpers" configured then my original inverter board does.

I do not know if perhaps thats why this new board doesent work, or if its a power supply issue, or what the hell. I will probhably have to wait untill a simular tv comes into my posession to do some testing of the boards i have in order to determine what the heck is going on..

[cadiman]

Re: wow!2007 jvc lt-42e488 bad caps!

You seem to be talking to yourself over in the corner!

You have the 24vdc with the inverter unplugged?
Do you remember ohms law?

check the 24v supply out of power supply with and without the inverter hooked up.

Too much load and the v drops.

You can check load on ac in cord with inductive amp meter. I know you have one!

[cadillacman]

Re: wow!2007 jvc lt-42e488 bad caps!

i dont have a service manual, and the boards are unmarked so i do not know what pins are 24v.. if i can figure that out, i will test and post readings..

[cadillacman]

Re: wow!2007 jvc lt-42e488 bad caps!

Ok.. used my head a little bit here... pulled the power board, followed the leads off of the 4 filter caps near the inverter connector.. founds pins 1-5 are +, pins 6-10 are - so with the connector unplugged, power on, i have 24.4 vdc...

power down.. hook up inverter.. power back on, 24v, UNTILL the backlights try to fire then it goes down to like 5vdc, then after failing to light the backlights i hear the relays clock off tv goes into protection and voltage drops from there..


I suppose the next thing to do is pull one fuse at as time fill i find the issue mabye..

edit: aha if i pull f100 on the inverter board the set powers on stays on and 24v stays at 24v...

time to dig further

[smason]

Re: wow!2007 jvc lt-42e488 bad caps!

Holy crap! I had no idea about these "kill switches"

[cadillacman]

Re: wow!2007 jvc lt-42e488 bad caps!

pulling either smd fuse does the same thing but that isnt the way to find it..

its only after the backlights have fired and shut down that my 24v dies...

its time to call it a night, ive had enough.