Goodmans GTVL19W19HDV

[sabre504]

HI i bought this 19" tv/dvd for the screen for another job that has not come up so thought i would check out the problem see if it could be sorted .

Standby light on the front flashs very quickly between green and red this is constant , and was told by the seller that the psu was ok so assumed it was the main board .

I have opened up the unit and the screen tests out fine on another monitor (Philips php x19) so that rules that out .

Psu checks show that the 12v is showing 16.7v now correct me if i am wrong but that seems excessive and may be the cause of the problem ?

Where the connection goes into the main board at the 5v end there is a 50v 220uf cap and 12v end there is a 16v 470uf (therest of the caps on the main board are 16v)

I have attached some pictures to show layout and a pinout sketch with legend and actual voltages sorry they are a bit poor on quality but main camera died due to dead bats and had to use phone one for now .

Any thoughts or input welcome

[sabre504]

Re: Goodmans GTVL19W19HDV

Have stripped the board of the cage and heatsink which in turn meant i had to desolder both schottky diodes as they are screwed to the back of the cage behind caps (noted that the cage has been bent and this has lifted the pads for the diodes ).

Under cage

2 x Capxon 25v 1000uf (original red mark)
1 x nichcon 16v 1000uf (second hand green mark)
2 x Koshin 16v 1000uf (second hand yellow mark)
1 x Samxon 25v 470uf (original? pink mark)

2 diode packs test ok .

Not sure now if the caps should be 16v as all the others are rated at 25v.
I know its ok to go up in vpltage but i still cannot find a diagram of the psu or data sheet to verify the outputs.

Will replace caps with new and take it from there ,any thoughts anyone

Ps camera still not working sorry bout poor pic but just to show cage

[momaka]

Re: Goodmans GTVL19W19HDV

Will replace caps with new and take it from there ,any thoughts anyone

Sounds good to me. Given the discoloration on the PSU board, those caps were probably already toast (even likely the Nichicon).
By the way, what series were the capacitors?
Make sure the ESR and ripple current ratings of the new caps are the same or better that the original ones (but again, you need to know what series the original caps were).
Also, if any of the original caps were rated for only 85C, don't replace them with 85C caps. Use 105C rated caps instead.

Psu checks show that the 12v is showing 16.7v now correct me if i am wrong but that seems excessive and may be the cause of the problem ?

Yes, that's a bit high. But it may or may not be a problem, depending on how picky the rest of the TV circuits are about this voltage. Some PSUs just regulate one rail and let the other one float where ever it wants to (not a good design, but I've seen it).
In any case, if your 12v rail is over 16v, make sure that all of the caps on that rail are rated for at least 25v. Check the other circuit boards in the rest of the TV as well - if there are any 16v caps that are using the "12" rail, then you certainly have a problem.

[sabre504]

Re: Goodmans GTVL19W19HDV

Hi Momaka the main board apart from one cap are all 16v so that rang small alarm bells but one is a 50v 220uf .

These i will look at after i have done the psu and see if changing the caps has sorted the voltage problem .

Capxon were KM 105c

Nichicon were KZE (think it was nichi) 105c

Koshins were obviously secondhand had old silicon on them i just chucked em as not impressed with them so didnt note which they were .

Thanks for the input will report back when have done the work

[jetadm123]

Re: Goodmans GTVL19W19HDV

KZE caps would be Chemicon and not Nichicon.

[sabre504]

Re: Goodmans GTVL19W19HDV

Ah of course only had a shield and KZE ,
even so still used ones so not sure they were ok on esr or capacitance

Still not finished building esr meter but thats another project .

[sabre504]

Re: Goodmans GTVL19W19HDV

Changed the caps and replaced them all to the same voltages and uf ratings.

Psu stiil showing 16v at the 12v pins ,but slight improvment it is now a steady 16.5v rather fluctuating between 16.6 and 16.8.

Checked voltage regulators on main board and they are showing 1.8v and
3.3v as they should be .

So i can only assume as the power light is still flashing green and red very quickly that the problem must be somewhere on the main board .

Just wondering if i jury rigged in a 12v psu and a seperate inverter board if the lower voltage would make any difference ?
But am expecting it wont so any thoughts anyone maybe a list no doubt of things i haven't tried yet

[momaka]

Re: Goodmans GTVL19W19HDV

Psu stiil showing 16v at the 12v pins ,but slight improvment it is now a steady 16.5v rather fluctuating between 16.6 and 16.8.

Well, if you have any 16v caps that are directly connected to the 12v rail, then this overvoltage is still quite a big concern.

So i can only assume as the power light is still flashing green and red very quickly that the problem must be somewhere on the main board .

Still can't say for sure.
Is there a pin on the PSU connector labeled "PS-ON", "PWR", or something like that? Or the logic board, perhaps? If there is such a pin, see if the voltage is fluctuating on it.

Just wondering if i jury rigged in a 12v psu and a seperate inverter board if the lower voltage would make any difference ?

I doubt it would as well, but try it anyways. Should be pretty easy, so I don't see why not. When in doubt, I always use an external PSU.

[alexanna]

Re: Goodmans GTVL19W19HDV

There's a voltage I'm wondering about, I don't see a backlight on pin listed.
Wondering if it's the BK pin?
Try pining in to the BK pin and then apply power to the board.
Doe the BK pin show any indication of the voltage trying to rise?

[sabre504]

Re: Goodmans GTVL19W19HDV

Bk on shows no voltage , Ps on constant 2.6v.

Am going to try rigging another psu but am not holding out much hope on this making any difference .

Also checked the 12v input on the DVD panel this also shows 16.5v .

All checks have been done with the lamps both connected and disconnected
and no difference in voltages (no load being imposed)

[sabre504]

Re: Goodmans GTVL19W19HDV

Right start again camera working better pics

Stripped the PSU again back to square one

Voltages

pins 1 and 2 (12v) showing 16.5v

pins 3 , 4 , 7, 9 and 10 (GRND)

pin 5 (ADJ) showing 5v

pin 6 (BK on ) 0v

pin 8 (PS on) showing 2.6v

Pins 11,12,13 and 14 (5v) showing 5 volt

Diodes packs on cage
Red marked is a F10SC9
diode test 155 each leg no reading in reverse
resist test 100 ohm each leg (x10 setting) no reading in reverse

Yellow marked is a MBRF2045CT
diode test 195 each leg no reading in reverse
resist test 80 ohm each leg (x10 setting) no reading in reverse

[momaka]

Re: Goodmans GTVL19W19HDV

Hmm...
Try disconnecting the PSU from all other boards and then apply power to it. See what voltages you get and compare them to when you have it connected to the rest of the TV.

I'm particularly interested in the voltages for BK ON, ADJ, and PSON.
The PSU traces seem to point that BK ON is indeed the backlight ON/OFF triggering circuit and ADJ adjusts the brightness of the backlight.

Also, I wonder if the inverter is somehow faulty and causing this condition. Another thing to try is to remove JP6 on the PSU and see if you still get blinking light on the TV. Removing JP6 will disable the inverter.