Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

[Dannyx]

Re: Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

Yes, it is - time for a new board then.

[robertkendrick]

Re: Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

Just a note to say I also had the same problem with C397. It was reading about 250 ohms each way. Replaced and now TV up and running.
My 17IPS20 R6 board was pulsating on the first controller. Something was pulling it down.
The first IC controller is fed from VCC_Main while the other two from VCC. I found it convenient to remove Q216 (an ordinary transistor) from the board which isolated the other two controllers from VCC. This brought the first controller back to life with correct voltages on the secondary transformer windings. Then it was a question of finding where the problem could be. OP, thanks for all your help.

[bolob]

Re: Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

Hi Guys,

I have a 40" Technika LED TV (Tesco brand) using the 17IPS20 -R6 PSU. Few days ago the problem started with the TV, no picture, but sound still it has. (I haven't seen this condition my wife told me) so I am not sure the backlight went off, or there was no video as well that time). She tried to power off and on, but after sound also disappeared. The current condition , after connecting the plug to the main, the red standby led flashing 7 times and after going to be off. It didn't try to switch on the backlight, also no electrical sounds coming form any transformers/coils. I was checking all the diodes, and transistors, I couldn't find any shorted or broken one. Any advice with this would be highly appreciated. In the above described condition, should the board supply any voltage for the LED strips ? Is there any sense to check the voltage in the connector of the backlight ? Or what is the easiest way to identify the problem with the board or with the backlight itself ?

Thanks in advance,
Br,
/bolob

[Dannyx]

Re: Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

Can you see any picture on screen by shining a bright flashlight onto the screen ?

How was the LED behaving when the TV WAS functional ? Was it off when the set was on and red when off ?

Measure the voltages present at the connector between the main board and the power supply - there should be a pinout printed on the board to help you and some pictures of your board would also help.

[bolob]

Re: Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

HI Dannyx,

Thanks a million for your reply.
Before I am starting to measure some voltage in the connector, I want to make clear about some conditions.
Should I connect the main board to the PSU and make the measurement by that way, or, can I do it the main board disconnected status from the PSU as well ?
Also, I just wondering, might I can use the LM7805 linear regulator connected to the 12V VCC and give the ST_BY pin supply if it is necessary. ( Sorry I didn't went deep enough to understand the schematic fully, but I guess to start the PSU in full fuction way, I need to supply some voltage (might 5 V ?) to the ST_BY pin in the CN4 connector.
As I checked the pictures what you attached to your post, my board looks completely the same as you have/had. only difference my PCB is not that brown around the FET (Q301) . Also by analyzing the boar, this guy doesn't have the +5V stabilizer, so the pin +5_STBY in CN4 is not connected to anywhere in the PCB. The jumper and all the regulator parts are not installed. So, my expectation if I connect the PSU to the main, I supposed to measure the 12V in the connector, even it is not pugged into the main board socket. Right ? By the way, the main board is 17MB82S.
Regarding your question, about what was the behavior of the standby led whe the TV was operating, well..... we are not sure. As I remember the LED was on when the TV was off, so it was signing standby function. According to my wife it was on when the TV was on.... brrr... sorry, the TV was in the kids room, so we not really often were checking it. Also kids only 5 years old, they don't remember for it.
I will try to come back within today with some measurement result from the PSU connector directly without connected to the main board.
Thanks for your help in advance.

[bolob]

Re: Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

Hi,

I did some measurement in the CN4 connector. 2,4,6,8 pins are DGN, on 10, 11, 12 pins I can measure 12.48V.
I also checked the pin 1 which has name in the schematic as PIN_1, only few millivolts I can measure which is not stable 1-3.5mV. After connecting the connector to the main board, the voltage on the 10,11,12 (all the three are sorted in the PCB) dropped by 0.02 Volt. So, seems there is no huge load from the main board.

ST_BY : remain close to 0V (actually 18mv) when the led blinking and after as well
BL_ON/OFF : Wile the led blinks almost 0V, when the LED went off this pin will have 5.2V.

PWM_DIMM : while the LED blinks 3.3V after 1.9V
On the backlight LED connector :
No voltage, except for few milisec. when the board swiching the 5.2V to the BL_ON/OFF pin I can see some change in the digital multimeter, 2-3V value, but shortly going to be 0 again, and stays as it is. (CN501, pin1 and 7 where the backlight is connected)

[Dannyx]

Re: Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

My best guess at the moment is that you have a bad mainboard with a short somewhere, though I must admit I haven't had a 17mb82S do this so far, but there's a first time for everything. This supply has no separate 5v standby output - it always supplies 12v to the main board which then handles standby on its own, if I remember correctly. Try testing your TV in "blocks". Here's what I do.

You can try feeding the board 12v from a separate supply to see what happens, ideally a bench supply so you can monitor the amps it draws. You won't have any backlight if you try it like this, but you should still see the TV coming on by looking at the screen with a bright light like I mentioned (IF the MB is functional !). Can't tell for sure how much current a functional board should draw, but if the amps start to go crazy and the supply shuts down or enters CC mode (if it's a bench-top supply set for a low current limit), you know you've got a problem somewhere on the MB and should dig deeper. Fortunately you can find schematics for Vestels relatively easy.

That 12v output can also be loaded with a 12v car lamp for testing purposes if you don't have an adjustable load. It should remain stable as the bulb comes on. A PC fan could also be used (or perhaps several of them, since they're pretty light loads).

[budm]

Re: Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

ST_BY pin is PS-ON pin, it should change state when power switch toggle on and off, in this TV the ST_BY (PS-ON) is active low.
So do you have switched 12VDC? Do you have PFC Boosted Voltage on the main filter caps (measure it between the two legs of the cap)?
Can we see good clear straight shots pictures of the whole power supply board and the whole backside of the TV showing all the boards?
Please note that the schematic shows all the parts for making the circuit board so your circuit board assembly used in your TV may not have all the parts as shown in the schematic.

[Dannyx]

Re: Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

Thanks for setting me straight on the backlight operation. It's sad, but I haven't worked on a TV for what seems like ages, so I forgot all the differences between models that I used to know by heart...

[bolob]

Re: Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

Sorry for letting you wait long. I have been out for long weekend, hopefully today afternoon I can deal a bit with the TV again. I will attach the requested pictures soon.

[Roktaal]

Re: Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

Hi guys.
If I may hijack this thread as I have same issue with Vestel 17IPS20 V6.
After a lightning storm, power board died burning D112 and D114 along with the FS100. After replacing those board was still dead. After reading in this thread about U202 I found out that pins 5 and 6 are shorted. D298 came out as ok as well as C296 but C295 appears to be dead. I removed all 3 yet pins 5 and 6 were still shorted so I assume U202 is dead.
Tomorrow I'll buy new FAN6300A as well as replacements for those condensers. My question is can someone confirm that both C295 and C296, according to schem provided by Dannyx, are 1uF 50V since the two I removed from the board differ in size.

[Dannyx]

Re: Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

Considering the caps are mostly used for filtering, I assume they're not THAT critical (I used an electrolytic one after all ), so I wouldn't worry too much. Go with what the schematic says.

PS. Damn, I never thought this post of mine would help so many people, or at least not enough for them to thank me Cheers guys.

[Roktaal]

Re: Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

Thank you for your reply and for this post Dannyx. I replaced U202, C295 and C296. Used 1uF 50V as suggested. TV is now fixed . Yay me, Dannyx and all others that left their comments and thoughts here.

[gianniveloce]

Re: Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

Thank you for your reply and for this post Dannyx. I replaced U202, C295 and C296. Used 1uF 50V as suggested. TV is now fixed . Yay me, Dannyx and all others that left their comments and thoughts here.

Hi there Old post but looks I have the same issue with mine!!! Thanks.
Caused by a short when backside of the board touched accidentally the TV metal frame and blown the onboard fuse as well as tripped the home el. panel fuse.
I already verified that D112/114 are definitely shorted (by desoldering them) According to schematic they are RL207
C295 and C296 look ok but found some more shorted SMD diodes (Measuring their resistance on the board with Ohmmeter)
D298 Zener looks shorted (C18V)
D213 D111 D307 look shorted as well (1N4148)
Looks also the 3 caps near the input are dead? as measuring with Ohmmeter on board I dont see 'pulling' any voltage
C152 (100nF 275V)
C142 (56n 275V)
C151 (56n 275V)

Would also like to ask if there s anything else to check before ordering/mounting the new components.?
Being an amateur in electronics i accept with pleasure any advice or even critical comment

TIA
GV

[elviscen]

Re: Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

Hi to all,

I have a Vestel 17IPS20 R9 (071114 R9) that dead after thunderstorm.
I measure all and on the output connector there is on all pins 0V.

Take measurement and have just 400V, measured around 320V.
All components are good, measured all diodes, caps, etc.

I haven't VCC, VCC_MAIN, AUX_M all are 0V.
Where can be the problem?
Maybe need to replace U101, U217, U300???
All three IC's haven't power VCC, all three have 0V.
On IC U217 on pin 8 (HV) I have around 114V.
Also measuring between pin 4 (GND) and pin 6 (VCC) i have 1,3kOhm, regarding some troubleshooting I see than need to be around 730kOhm.

What you suggest?
What can be wrong?
Change the IC U217 or all three IC's?
Something other to verify, change?

Thank you.

[R_J]

Re: Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

Start by checking Q211 and source resistor (R228 or R235) note these values are wrong and the resistor is usually around 1Ω. If Q211 is shorted you need to check the gate drive components and likely also replace U217

[elviscen]

Re: Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

Hi,
Q211 and R235 are good.
I change the U217 with U300 and now power supply are life again just without backlight.
I ordered new U300 and hope will arrive sone.

[samtron786]

Re: Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

Hello
I have 3 pieces here as 0.06 ohm and a capacitor C305 short circuit
R370 -0.06 ohms
R113 -0.06 ohms
R228 -0.06 ohms

what are the resistance values?
where can you order it
many thanks

[Dannyx]

Re: Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

It's unlikely the resistors are bad - they fail open rather than shorted. Something across them, like a capacitor, is shorting them out. You already mentioned a cap is shorted, so how about removing it and checking again ?

[samtron786]

Re: Dead Vestel 17IPS20 power supply repair (OK fuse, no shorts)

Hello
capacitor
ESR 0.85ohm
Vloss=0.8%
48.50uF