T-Con repair help

[caphair]

Re: T-Con repair help

@momaka thanks for the info. I’ve done a resistance measurement on all those test points and none appear to be shorted. This is without the panel connected

My question now is, does the fuse F1 protect all those voltage rails? If it blows does that mean one of them has short circuited or a specific one?

[NeedsMoreFlux]

Re: T-Con repair help

Is F1 the only fuse on the tcon board?

If the fuse blows it could have a short circuit. it may be getting too much power from the power board. It could be shorted to another circuit.

Can't think of any other potential causes for a fuse to blow...

I am working on a tv that had a 7amp slow blow fuse with super high resistance. with power on it had 24v in and 5v out.

I soldered on 2x 3amp fuses. the fuses have not blown but I have not yet found the problem. I need an old CFL spiral bulb to test the output of the inverters-10K VOLTS!!! When I have time I will trace the circuit a little more and make sure that the coils are actually getting the proper voltage. Which may be higher than my harbor freight meter can handle.

[NeedsMoreFlux]

Re: T-Con repair help

There’s only one cable per connector on the t-con (one from mainboard to t-con and one from t-con to panel) and the fuse F1 is open so how would I even try to get a picture through the t-con board?

I should have been more clear. I was reading an article from justineyoung.com(?)

where he has 2 ribbon cables coming out of the tcon board-into the panel, and he unplugs one side-gets black screen. plugs that cable back in-unplugs the other side and gets a picture on one side.

[momaka]

Re: T-Con repair help

@momaka thanks for the info. I’ve done a resistance measurement on all those test points and none appear to be shorted. This is without the panel connected.

So what resistances did you get.
And what happens to the resistances when you connect the panel?

That said, can you turn ON the TV with the panel disconnected but T-con still connected?

My question now is, does the fuse F1 protect all those voltage rails? If it blows does that mean one of them has short circuited or a specific one?

Basically, F1 protects only the VCC rail. But because all of the other rails are derived from VCC, then if one of them becomes overloaded, it will also overload VCC and hence blow the fuse or make the power supply shut down.

That said, you do bring a valid point I forgot to mention: the main boosted voltage rail may sometimes become shorted to VCC. Thus, also check for short-circuit between VCC and VDD. In cases like that, you will want to check the rectifying diode - on your board, that's SMD diode D1.

Another thing worth mentioning: I now see that your T-con has two inductors and two diodes (don't know how I didn't notice it the first time ). That suggests two boost/buck rails, which kind of throws me off. But I'll check the TPS65163 IC datasheet to, as that might explain why - usually T-con boards follow the sample circuit very closely for their boosted rail IC (i.e. the TPS65163).

Meanwhile, also perform the following resistance tests:
check for short-circuit to ground at the resistors above VHG - that is, check on their upper leads, where they connect to R106 and C54. While at it, check Zener diode ZD1 as well.

Finally... and this may be a bit more tedious, but I always find it worthwhile: check *all* ceramic capacitors for short-circuit. Any capacitors that reads less than 50 Ohms across, post it here.

*EDIT*
Ceramic cap C22 also looks a bit dark compared to C21 next to it. Not sure if that's normal color variation or not, so definitely check it too. C22 and C21 are located to the left of fuse F1.

*EDIT 2*
Sometimes you may not get a reading on the board because of dried flux that was leftover from manufacturing. Thus, before concluding a component is not shorted or showing any resistance, make sure you move around your multimeter leads on the solder joint, as that will break the dried flux and make a proper connection.

momaka I copied above post for future reference.

Cool. I'll try to dig out my other posts. I know I had a few that were very long and detailed. Should have bookmarked them.

[caphair]

Re: T-Con repair help

Thanks for all your help. I measured D1 and it read .022v in diode mode on cathode side traced to output caps C31 and C32 I checked under a microscope and C31 had a very small fracture so I removed it.

Now diode mode reads .325v and C31 off the board measures 40 ohms so that was the issue.

Now do I need to replace the cap or can leave it off? Don’t know it’s value to replace. C32 measures 1.023nf so I’m guessing can just use another with similar rating?

Also (since I suck at conversions) would that be 10UF?

And finally regarding the fuse it’s labeled TK but I can’t find replacements online. Are K fuses the same?

[momaka]

Re: T-Con repair help

Now do I need to replace the cap or can leave it off? Don't know it's value to replace. C32 measures 1.023nf so I'm guessing can just use another with similar rating?

1 nF seems very small for that cap. Are you sure it's not 1 μF?

You could leave it out to test if the TV works. But I strongly suggest you replace it with same or slightly higher capacitance.

Also (since I suck at conversions) would that be 10UF?

No.

1 μF (microFarad) = 1000 nF (nanoFarad) = 1000000 pF (picoFarad)

also:
1 uF (microFarad) = 0.001 mF (milliFarad) = 0.000001 F (Farad)

And finally regarding the fuse it's labeled TK but I can't find replacements online. Are K fuses the same?

To the right of that fuse says "63V/1.5A".
Code "K" for SMD fuses typically means 1.5A... so just look for a "K" SMD fuse online that has the same physical size (length and width) as yours.

[caphair]

Re: T-Con repair help

Thanks yeah it is a 1uf my meter read 1.023nf but using the conversion it’s 1uf

Regarding the fuse th only K smd fuses I find are rated 1.5a/32v can’t find any 63v within the country.

The circuit wouldn’t need up to 63v protection right?

[momaka]

Re: T-Con repair help

Thanks yeah it is a 1uf my meter read 1.023nf but using the conversion it’s 1uf

1 uF is 1000 nF
and 1 nF is 0.001 uF or 1000 pF.
Did you mean to say your meter is showing 1023 nF (without the decimal)? If so, then yes, that is 1 uF.

Regarding the fuse th only K smd fuses I find are rated 1.5a/32v can’t find any 63v within the country.

The circuit wouldn’t need up to 63v protection right?

No, not at all. A 32V fuse would be fine. After all, you are only running 12V through it.

[caphair]

Re: T-Con repair help

My meter reads “1.023 nf” so I’m confused as well lol

[petehall347]

Re: T-Con repair help

try a known good 1uf with your meter .