JMB JT0246001/01 Stand by issue

[finntricky]

this is an intermitent problem with the standby light,
the light will turn on when first pluged in and stay on for around 15 seconds before going of,
other times the standby light will stay on for hours.
after doing volt checks on PS, all are correct, 5 volt standby is constent from the board to the main board,
now this has a 2 colour LED, red for standby and blue for on, while the red is on i read 1.78v, when the light goes out after 15 or so seconds the reading drops to 0.28v.
now, i must point out that if you hit the power button at the right time the tv will come on and stay on with now problem for days, other times if the timing ain't right the standby light will turn blue to say its on, but nothing happens.
any ideas ?

[Agent24]

Re: JMB JT0246001/01 Stand by issue

Bad connection somewhere perhaps?

[finntricky]

Re: JMB JT0246001/01 Stand by issue

thought that myself, but have checked for bad connections and can't find any,
seems strange that volts only drop once light goes out,
in other words the light goes out first before the volts drop out.
could this be a bad LED ? or is it pointing towards the main board ?
i have removed all caps from standby board and main board and all tested fine,

[tom66]

Re: JMB JT0246001/01 Stand by issue

Your meter is not fast enough to show the sudden change in voltage, most meters only take readings twice or three times a second, and analog meters also have a bit of a lag. I doubt the LED is bad but even if it was it wouldn't stop the TV powering up.

Try checking the voltage regulators on main board & PSON signal from main board.

[finntricky]

Re: JMB JT0246001/01 Stand by issue

tom, can you point out regs from my pics at all ?

[tom66]

Re: JMB JT0246001/01 Stand by issue

See this thread
https://www.badcaps.net/forum/showthread.php?t=22231

[finntricky]

Re: JMB JT0246001/01 Stand by issue

thanks tom, that helps alot
this is my findings
reg is
1117 - 8
AD 642 k
pin 1 = 0.61 and sometimes 0.00
pin 2 = 1.87
pin 3 = 3.52

all other regs read the same
pin 1 = 0.00
pin 2 = 3.30
pin 3 = 5.15

all reading done from left to right, gnd out in


so looks like i have found the bad reg, YES ?

[tom66]

Re: JMB JT0246001/01 Stand by issue

The reg with the leg at 0.6V may be OK, it is an adjustable type. However please check the voltages on this regulator when the TV works and when it does not, including both when the power light stays on or goes off.

[finntricky]

Re: JMB JT0246001/01 Stand by issue

standby on = same readings, standby of = same readings, and still the same with tv on and working

[flocko]

Re: JMB JT0246001/01 Stand by issue

i have had problems with JMB sets stuck in standby and its all ways been eeprom try with main board number T.MSD 306.69A and look on OHM supplies and see if Andy does one,it my not be for this set but if it has same panel it could work, also try looking up the Sky media web site there could be a firmware update on this model Flocko

[finntricky]

Re: JMB JT0246001/01 Stand by issue

been to there and no firmware updates for any jmb tv that i could find anyway.
can't find a board for this 46 in samsung screen, thats why i thought i'd have a go at repairing it,

[flocko]

Re: JMB JT0246001/01 Stand by issue

look on Ohm supplies for a replacement eeprom that should repair your main board the thing is all these set suffer for the same problems but there is no backup, they will take £140 off you to repair a firmware problem. the last one i did was a 32" with dvd got an eeprom from Andy but was not for this model same main board number and screen but no dvd, it fix the standby fault but dvd did not work so had to get new main board,i think i have seen a 46" JMB on ebay near me with a damaged screen, i will look and see if it is still on there if it is i will see if i can get it flocko

[flocko]

Re: JMB JT0246001/01 Stand by issue

Sorry the one that is on Ebay was a 50" from Gillingham (Medway) so i dont think will be any good for you Flocko

[finntricky]

Re: JMB JT0246001/01 Stand by issue

yeah i see it myself,
im gonna try and change the voltage reg, just got to find one the same or compatable.
i'll look on ebay,
thanks for your input

[flocko]

Re: JMB JT0246001/01 Stand by issue

the regulators look to test fine but your call did you look for an eeprom ?what is the pannel number just cant make it out from photo Flocko

[finntricky]

Re: JMB JT0246001/01 Stand by issue

Lta460hm06

[flocko]

Re: JMB JT0246001/01 Stand by issue

Ohm Supplies list for a technika 40" that has the same main board T.MSD306.69A and all so uses the LTA4000MO7 samsung panel and lists as cct u10 that must be on the back of the board as not in photo,if it was me i would first check that your board has the eeprom there, and if so i would give it a try, as all these are made by the same factory and with the same main board and panel (LTA)as yours i am thinking it will work,as i said i have done this mix and match before and it worked i cannot 100% say it will but the odds are on your side Flocko have looked on Ebay and main board is the same type 181432735269 in to ebay to look

[finntricky]

Re: JMB JT0246001/01 Stand by issue

beginning to think firmware as well now,
as i have just discovered that the power to the main board all shuts down after 15 seconds except the standby power, this keeps the standby light on solid with no probs.
it seems that the boot process gets to the point of saying, ok im ready to go,
or it get to the 15 seconds and says, no way and shuts of the standby light, and leaves power on the mainboard, while it tryes to sort it's self out,
how does that sound

[flocko]

Re: JMB JT0246001/01 Stand by issue

well i have found you the eeprom so its your call fit it or get a new board, send it to Sky to fix, but it wont fix itself, we have got others on here now with problems with these UMC sets having to be retuned every time there turned on, all firmware problems that they know about but do nothing to cure, Flocko

[finntricky]

Re: JMB JT0246001/01 Stand by issue

update
had words with sky media, and they say that the eprom or firmware is not at fault,
they also said that they are experts because they make the tv, and the problem is the MOTOR BOARD ? what ever that means, any ideas,
they will supply me with it for £45 +p&p +vat, so about £60, bit over the top for a cheap and chearfull tv.