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

[dick_barton]

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

I have just taken another look at some of the readings you have supplied. TP34 = 0.6V?
but D2017 should have 0.7V across it and the emitter / base voltage of T2002 should also have 0.7V across it so the base of T2002 to ground should measure approximately 1.4V minimum to turn on the transistor.

[stomanata]

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

I don`t know about TP34. D2017 and T2002 are OK.
I remove 560 ohm for OLP and remove R2054.
Turn on TV, but it start to work for 2-3 secs and then turn off.

[dick_barton]

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

Resolder R2054 back in place and repeat the process for each of the other 3 resistors.

[stomanata]

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

Ok. Thanks. I`ll do it

[stomanata]

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

The result is the same - every time it start for 2-3 secs and
then turn off

[dick_barton]

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

So with all 4 resistors removed one at a time, the lamps still switch off after a few seconds?

What is the voltage at OLR pin 2 of IC2006 with the 560 ohm resistor still disconnected.

With the set off and your meter set to diode mode can you check D2017 and T2002.
T2002 should read 0.7 between base (TP34) and emitter (TP36).

[stomanata]

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

Yes - i remove resistors one by one and every time it start for 2-3 secs.
Voltage of OLR when it work is 0.1V.
D2017 and T2002 are OK - i test it with removing them from PCB.
Also 4 resistors are 33K.
And yes - it is 0.7V. Base-colector is 720, and base-emiter is 724mv

[dick_barton]

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

Was the base/collector voltage (0.72V) measured when it was out of circuit because if it was then the transistor is faulty.

Other than that I cannot think of anything else to try other than replace the FAN7314

[stomanata]

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

It was measured on PCB.
May be fault in transformer is caused fault in FAN7314?
But if i shunt OLP everything work, but there is high frequency noise - something
overload system...

[dick_barton]

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

What did collector/emitter (TP33/TP36) resistance read with meter in diode mode, the 560 ohm resistor removed and the set switched off?

[nomoresonys]

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

Caps C2067, C2069, C2015 and the one next to it checked out alright?

[stomanata]

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

T2002 soldered on PCB
1. negative on emiter, possitive ot colector - 1671
2. Possitive ot emiter, negative on colector - 1091
About C2067 and other next to connectors...
I use tester like this https://www.aliexpress.com/item/3299...archweb201603_
but it start from 25pF, so on all of them it show "unknown or damaged".
I try with multimeter on 2Mohm to check in both directions and multimeter
didn`t read any resistance.
Now i`ll try to desolder them and check it 2pcs at once.

[stomanata]

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

i can`t test them
i solder 3pcs in paralel, this must be 45pf and try to test them
but again it show "unknown or damaged".
How can i test them?
May be if i solder diode in series and connect it for short time to
AC230V and then to check is there spark? But capacitance is too small, so
may be it will not help me...

[nomoresonys]

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

To test the capacitor with a multimeter, set the meter to read in the high ohms range, somewhere above 10k and 1m ohms. Touch the meter leads to the corresponding leads on the capacitor, red to positive and black to negative. The meter should start at zero and then moving slowly toward infinity. Suppose it could still have bad/low esr tho.

[dick_barton]

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

Can you use your tester and test that transistor T2002 out of circuit.

[stomanata]

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

This situation with meter from zero to some readings is for high capacitor - some
microfarads. This capacitors are 15pf, this is too small and can`t use this method.
T2002 outside PCB also is OK

[dick_barton]

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

Other than changing the FAN7314 I don't know what else to try. Anyone else have any ideas?

[nomoresonys]

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

This situation with meter from zero to some readings is for high capacitor - some
microfarads. This capacitors are 15pf, this is too small and can`t use this method.
T2002 outside PCB also is OK

Change m out to rule m out I guess.

[stomanata]

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

Oh... it is too complicate.
FAN7314 drive transformer and receive feedback from lamps.
OLP cause the TV to stop working, but why?!?!?
From 3 lamps i measure ~2v, and from 1 lamp i measure ~0.2v.
Now i try to change capacitor next to connector with 0.2V and put it
on opposite lamp (from #4 to #1 for example). Again on this connector
i have 0.2. So it is not problem in 15pF capacitor.
May be it is problem with this lamp, lets name it as #4.
But with my backlight tester i connect:
digital wattmeter - computer psu - backlight tester.....
It has 4 outputs, but cables are short and i can connect only 2 lamps.
I connect #3 and #4 and power them up. Wattmeter read ~13W.
Then i disconnect them and connect #1 and #2. Wattmeter again
read ~13W.
This mean that all 4 lamps has the same power consumption.
When i power TV with 560 ohm resistor on blue screen backlight seems to be OK.
But something broke OLP and tv goes off.
TV has burned 1 (of 2) secondary windings of HV transformer.
For me there is something about OLP line, but all components seems to be ok.
May be there is problem that happen when TV work. Without power socket when
i measure component by component all looks fine...
For now i see 2 ways to fix it:
1. To continue to work with 560 ohm, but this is danger.
2. To buy led backlight and to try to change backlight. I never do this, but
i hope that i can do it
Other solutions?
IF it is 100% sure that FAN 7314 is defective - it is not problem to
buy new one and to replace it.

[stomanata]

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

Change m out to rule m out I guess.

???? i can`t understand this...