Tv Grundig Vision 2 22-2920 turn off after 2 secs

[stomanata]

Hi,
this TV stays on standby, but when i try to switch on via remote it
start for 2sec and goes to standby again.
Before this i change backlight transformer, dut to problem
in secondary windings. Also i change 220nF X2 capacitor.
It has PSU YTF194-08 V-0
Also i notice that voltages are 5.3V and 13.5V, but no idea
why both of them are ~10% up.
Capacitors on output are with low ESR - tested with MESR100
Any ideas what/where to check?

[dick_barton]

Re: Tv Grundig Vision 2 22-2920 turn off after 2 secs

Can you post some photo's of the circuit board as an attachment. Also of the capacitors and the transformer you replaced

[stomanata]

Re: Tv Grundig Vision 2 22-2920 turn off after 2 secs

Can you post some photo's of the circuit board as an attachment. Also of the capacitors and the transformer you replaced

Yes. Here are pics of both sides of PCB.
There is signs of flux because i remove some parts from PCB to
measure them. All parts that i test seems to be OK

[dick_barton]

Re: Tv Grundig Vision 2 22-2920 turn off after 2 secs

So the transformer is the same part number (TMS93633CT) as the original so that cannot be the problem.

I would check that the ends of each fluorescent tube are correctly seated into their connectors and not damaged.

Open lamp protection overide using 560 ohm resistor from Pin1 to ground

https://english.electronica-pt.com/lcd-repair?p=fan7314

[nomoresonys]

Re: Tv Grundig Vision 2 22-2920 turn off after 2 secs

Are those burn marks on S206 and S207?

[stomanata]

Re: Tv Grundig Vision 2 22-2920 turn off after 2 secs

I`ll try to turn off OL protection. Btw i test all 4 lamps with
my universal CFL tester and using digital wattmeter.
First i connect 2 lamps, and then second pair of lamps.
Both has ~13w consumption on app. half brightness.

Are those burn marks on S206 and S207?

may be you mean S2006 and S2007 - CFL connectors?
No, there is no burn. On the top there is some red mark with
marker...

Btw optocoupler seems to be a little burned around transistor side...

[dick_barton]

Re: Tv Grundig Vision 2 22-2920 turn off after 2 secs

I do not think there is a problem with the opto-coupler since you have the 5V and 13V supplies.
The photo of the back of the board is very out of focus. Perhaps you could post a good focused one.

[stomanata]

Re: Tv Grundig Vision 2 22-2920 turn off after 2 secs

I do not think there is a problem with the opto-coupler since you have the 5V and 13V supplies.
The photo of the back of the board is very out of focus. Perhaps you could post a good focused one.

But why 5 and 12v are high?
I make test with resistor - it work for 5-6 secs and
picture (blue sreen + no signal message) looks good, then
i turn it off.
I upload new pictures of back side.

[dick_barton]

Re: Tv Grundig Vision 2 22-2920 turn off after 2 secs

Are you 100% certain that all the lamps were working. With the overide resistor added did the lamps stay on until you turned off the set or did they turn off by themselves?

[nomoresonys]

Re: Tv Grundig Vision 2 22-2920 turn off after 2 secs

Maybe check all the diodes, diode mode, tv unplugged from power, see if you get a reading in one direction then reverse the meter probes should be OL or 1 in other direction.

[stomanata]

Re: Tv Grundig Vision 2 22-2920 turn off after 2 secs

Are you 100% certain that all the lamps were working. With the overide resistor added did the lamps stay on until you turned off the set or did they turn off by themselves?

Yes, i`m sure and they work.
Here are 2 pics with 14secs between them + some secs before
start camera

[dick_barton]

Re: Tv Grundig Vision 2 22-2920 turn off after 2 secs

+1
I would now do what nomoresonys has suggested and start testing the components and solder joints in that area.

Check you have 2.5V on Pin 6 of IC2006

[stomanata]

Re: Tv Grundig Vision 2 22-2920 turn off after 2 secs

+1
I would now do what nomoresonys has suggested and start testing the components and solder joints in that area.

Check you have 2.5V on Pin 6 of IC2006

Thanks.
Wich area you mean?
I`ll check later for 2.5v
All diodes and mosfets seem to be ok. I desolder both mosfets that
driver CFL transformer - both are ok.
In fact open lamp protection make all my problems, right?
But mosfets, transformer and all lamp are OK. So, may be some
component in OL line is defective?

[dick_barton]

Re: Tv Grundig Vision 2 22-2920 turn off after 2 secs

Can you measure the voltages at TP21, TP22 & TP34
TP21 =
TP22 =
TP34 =

and also if you have 2.5V on Pin 6 of IC2006

[nomoresonys]

Re: Tv Grundig Vision 2 22-2920 turn off after 2 secs

The bottom left of the board in your picture looks kind of tore up.

[dick_barton]

Re: Tv Grundig Vision 2 22-2920 turn off after 2 secs

Can you measure the voltages at TP21, TP22 & TP34
TP21 =
TP22 =
TP34 =

and also if you have 2.5V on Pin 6 of IC2006

What readings did you get. Have you found the fault?

[stomanata]

Re: Tv Grundig Vision 2 22-2920 turn off after 2 secs

Sorry for my late reply.

The bottom left of the board in your picture looks kind of tore up.

Which side - solders+smd or PTH elements?

What readings did you get. Have you found the fault?

I try to measure all transistors and diodes that are relevant to OLP, but all of them look OK.
About readings:
TP21=1.84
TP22=1.44
TP34=0.6
On pin6 of IC2006 there is 2.53v
All this is with 560 ohm resistor to ignore OLP

[dick_barton]

Re: Tv Grundig Vision 2 22-2920 turn off after 2 secs

About readings:
TP21=1.84
TP22=1.44
TP34=0.6
On pin6 of IC2006 there is 2.53v
All this is with 560 ohm resistor to ignore OLP

Can you also check TP93 and TP95 which I missed out of the above list to test.

Then take the same readings ( including TP93 and TP95) but with the 560 ohm removed
You need to check each point as you power up the set out of standby.

[stomanata]

Re: Tv Grundig Vision 2 22-2920 turn off after 2 secs

Now i test it but still with 560ohm resistor.
TP93=1.96, but after some secs it drop to ~1.85-1.9
Tp95= 1.71-1.75
At the same time i check again TP21 and TP22. TP21 is ~1.85, but
TP22 like my previous test is still low - this time was ~1.3v
Did you mean now to try to measure all of them withou 560ohm resistor?
TV will work for 2-3 secs and then will turn off.
May be there is problem with CFL connected to S2006, wich is relevant
to TP22?

[dick_barton]

Re: Tv Grundig Vision 2 22-2920 turn off after 2 secs

I really do not know what else to suggest.

The only thing I can think of is first remove the 560 ohm resistor.
Next remove resistor R2054 (TP22) and switch on and check if you have the backlights.
If you do not then replace R2054 and remove resistor R2053 (TP21) and again check if the backlights come on. If you do not then replace resistor R2053.

Repeat this for resistor R2056 (TP93) and resistor R2057 (TP95)

Hopefully this will identify which lamp circuit is causing the problem.