technika 42 lcd 910 power probs

[exmortis]

hi having probs with this , the unit powers up and the screen lights up for 20sec's and then powers down again , and the psu 17PW01-4 buzz's any ideas with this issue common i seen, cant see any badcaps on the board.

[tom66]

Re: technika 42 lcd 910 power probs

Your fault is different from last guy's. Check 24V across CapXon on inverters.

[exmortis]

Re: technika 42 lcd 910 power probs

Your fault is different from last guy's. Check 24V across CapXon on inverters.

ok all new to me , so i wouldnt know how to check that , i been told it could be a diode gone open letting through A.C

[exmortis]

Re: technika 42 lcd 910 power probs

ok all new to me , so i wouldnt know how to check that , i been told it could be a diode gone open letting through A.C

also the screen does not display anything , just the backlight on a black background ?

[vinceroger69]

Re: technika 42 lcd 910 power probs

is you multi meter auto ranging or manual can you post pictures of the boards on your set they we can point out for you the test points etc.

[exmortis]

Re: technika 42 lcd 910 power probs

is you multi meter auto ranging or manual can you post pictures of the boards on your set they we can point out for you the test points etc.

manual meter i add some pic's

[exmortis]

Re: technika 42 lcd 910 power probs

manual meter i add some pic's

the buzzing is coming from the little transformer fella i have high marked on the pic's , also marked these diodes which i was informed might be at fault

[vinceroger69]

Re: technika 42 lcd 910 power probs

put you meter on diode test and the three diodes you have highlighted should have a reading in one direction only if any read odd you will have to unsolder 1 leg on each diode and then retest them.
tom will explain what he needs tested and how ie meter setting etc if your not sure.
if your not sure of the meter settings post a picture up and we will highlight the diode and dc settings for you

[tom66]

Re: technika 42 lcd 910 power probs

This pic: https://www.badcaps.net/forum/attach...8&d=1361530364

Two brown caps (cylinders) on inverter board: check voltage across them.

[exmortis]

Re: technika 42 lcd 910 power probs

This pic: https://www.badcaps.net/forum/attach...8&d=1361530364

Two brown caps (cylinders) on inverter board: check voltage across them.

hi all thanks for quick replys ok

the diodes i get the same for all 3 a reading of 127-130

and the voltages accross the brown caps one reads 24v and the other only 5v the t.v slips back into standby, the caps look like they have been changed before lots of flux resin and moody solder joints.

[exmortis]

Re: technika 42 lcd 910 power probs

hi all thanks for quick replys ok

the diodes i get the same for all 3 a reading of 127-130

and the voltages accross the brown caps one reads 24v and the other only 5v the t.v slips back into standby, the caps look like they have been changed before lots of flux resin and moody solder joints.

ok got 24v from both brown caps
of them on the invertor boards before she shuts down .

[tom66]

Re: technika 42 lcd 910 power probs

Ah, so you get 24V, then it rapidly falls off? When it does this, does the power LED begin blinking?

[exmortis]

Re: technika 42 lcd 910 power probs

Ah, so you get 24V, then it rapidly falls off? When it does this, does the power LED begin blinking?

power led does not blink at all, i changed some of the caps on the isolated side of the psu, same as the other chap did, and now it switches on and then back off within a couple of seconds

[exmortis]

Re: technika 42 lcd 910 power probs

power led does not blink at all, i changed some of the caps on the isolated side of the psu, same as the other chap did, and now it switches on and then back off within a couple of seconds

i double check the led on the front tho now

[exmortis]

Re: technika 42 lcd 910 power probs

i double check the led on the front tho now

blue button stays on now solid on the front .

[exmortis]

Re: technika 42 lcd 910 power probs

blue button stays on now solid on the front .

i replaced the caps in red on the pic, now she switches on then off .

[exmortis]

Re: technika 42 lcd 910 power probs

i replaced the caps in red on the pic, now she switches on then off .

or completely stuck in standby mode help

[tom66]

Re: technika 42 lcd 910 power probs

Do you have 24V on those caps briefly when power is first applied to the set?
What brand and series of capacitors did you use?

[exmortis]

Re: technika 42 lcd 910 power probs

Do you have 24V on those caps briefly when power is first applied to the set?
What brand and series of capacitors did you use?

yeah i get 24v the it drops off and the cap's have no brand just some i picked up at the local electronics shop to match the ones to replace , 470micro 16v

but the behaviour of the fault has now changed

[tom66]

Re: technika 42 lcd 910 power probs

You need to use low-esr capacitors. Farnell sell them as do RS. Capacitors from the average shop can cause lots of issues. Good capacitors to use are Panasonic FC, FM or FR.