ALBA 42" Stuck in standby

[sabre504]

Hi all
a friend asked me to look at his tv as it had made a screech noise(as he put it) and then wouldn't come out of standby.

Opened up the unit expecting swollen caps but can see none ,i know that means nothing but there is a right mixture of Chang ,Samxon ,HEC and Fujicon .

Have tested bridge rectifier its ok ,fuses ok .
The only thing so far that jumps out at me is a diode that reads both ways but only in circuit pulled and tested off board it only reads one way as it should.

Not sure where to go with it now any help would be welcome

Pic 4 is the diode in question

[turbozutek]

Re: ALBA 42" Stuck in standby

I recently repaired a BAIRD TV with a very similar design and that was dry joints in the PSU caused by shitty lead free solder. Many of the joints on the BAIRD looked perfect, but bubbled up when I re-flowed them and looked pretty nasty afterwards, so I removed all the solder and re-flowed with tin/lead mix.

I'd start checking voltages with a DMM now.

[PlainBill]

Re: ALBA 42" Stuck in standby

It appears the outputs of the power supply are labeled; the pictures are so poor I can't be sure. In my experience, checking for proper output voltages is much easier than checking components.

PlainBill

[sabre504]

Re: ALBA 42" Stuck in standby

Apologies Bill hard to get decent light for good pictures bit grey and wet here .

Have done another pic as you can see there are no markings for expected voltages .

Black connector goes to the inverter panel so i would expect to see
12v/24v for supply ,ground and 3v/5v on/off

White connector goes to the main board so possibly find 3v/5v and maybe
12v to.

The three connectors circled in red are not used .

I have reflowed all components on the board and will try to get some readings and report back later

[sabre504]

Re: ALBA 42" Stuck in standby

sorry try these

[sabre504]

Re: ALBA 42" Stuck in standby

I have since tried another power board on this and still no joy think this may be a problem with the sensor touch switch .

Firstly let me apologise for the poor quality of the pics the batteries are nearly out

Pic 1 is the touch switch end and pic 2 is the main board end

The three wires run between these 2 points and each wire have continuity
red carries 3.8v blue 3.8v yellow 0v ,

Now i am assuming much like a monitor 1 line power constant and the switch allows the current to return to the main board to start up ?

That is not happening here i think the blue wire is for the infa red and the red wire is the manual control or vice versa , i am just wondering if i were to allow power back down the yellow line would it start up the tv ?

[japlytic]

Re: ALBA 42" Stuck in standby

I think those green electrolytics are Samxon GF, a known bad unit.

[turbozutek]

Re: ALBA 42" Stuck in standby

Yeah, good point they do look like Samxon - and if they are I'd replace them before trying to do anything further.

Horrible, horrible caps.

[sabre504]

Re: ALBA 42" Stuck in standby

I fitted a new power board and still the same so not the caps on the power board or do you mean the ones on the main board