17MB35-4 3.3V Shorted Help ?

**wills123** · 10-20-2015, 01:12 AM

Re: 17MB35-4 3.3V Shorted Help ?

Nice one hope you get it replaced easy enough

**ReeceyBurger123** · 10-20-2015, 02:19 AM

Re: 17MB35-4 3.3V Shorted Help ?

Originally posted by stj

does it have a pad under it?

No its just pin soldered which I can easily replace, I have a chip on order will make a youtube video on how it goes.

**ReeceyBurger123** · 10-20-2015, 02:22 AM

Re: 17MB35-4 3.3V Shorted Help ?

Originally posted by wills123

Nice one hope you get it replaced easy enough

Cheers pal, hopefully its just that chip

**ReeceyBurger123** · 10-20-2015, 07:44 AM

Re: 17MB35-4 3.3V Shorted Help ?

Picture of faulty Hdmi chip removed.

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**ReeceyBurger123** · 10-28-2015, 07:14 AM

Re: 17MB35-4 3.3V Shorted Help ?

The new Ic has arrived to day going to get on with installing it

Must say for coming from where ever in China this arrived fast and was well packaged. Welldone who ever sold me this

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**ReeceyBurger123** · 10-28-2015, 12:36 PM

Re: 17MB35-4 3.3V Shorted Help ?

Theres more to be done on this, I have replaced the Hdmi Ic successfully however the regulator U121 still has a short across the adjust and output pins. The Hdmi Ic now doesn't burn my finger however the regulator does and its not the regulator at fault. Any more suggestions ? Made it this far not ready to give up !

**tom66** · 10-28-2015, 12:56 PM

Re: 17MB35-4 3.3V Shorted Help ?

A short between adjust and output can be ok if the regulator is configured for 1.2V output. (That is how you get an adjustable regulator with 1.2V reference to output 1.2V)

BTW, nice work removing that IC! Bloody clean pads... How'd you do it? It took me years to get to the level of cleanly removing TQFPs etc.

**ReeceyBurger123** · 10-28-2015, 01:02 PM

Re: 17MB35-4 3.3V Shorted Help ?

Cheers mate here a pic of the Ic soldered:

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**ReeceyBurger123** · 10-28-2015, 01:07 PM

Re: 17MB35-4 3.3V Shorted Help ?

I did the following to go about replacing the Ic:

Apply Flux (gel type) around all pins of the Ic.
Use hot air at 400d and heat ic until flux is bubbling.
Focused heat on one side of the Ic.
When solder is melted on that side, use a small pair of tweezers and pry it up.
Apply heat to rest of Ic until it lifts.
When Ic is removed use solder wick and clean all pads down.
Use Ipa and clean all pads off.

I did the following when replacing the Ic:
Position new Ic perfectly.
Apply small amount of flux to each opposite corner
While holding Ic in place get some solder on iron and tac corners that are fluxed.
Check alignment of Ic again.
Flux all pins of Ic.
Flood all pins with solder.
Apply more flux and wick solder off with iron.
If there are shorted pins wick solder off with solder wick.
Clean with ipa.
Check with microscope.

When im finished doing this I will upload the repair log, I have recorded how I have done everything.

**ReeceyBurger123** · 10-28-2015, 01:17 PM

Re: 17MB35-4 3.3V Shorted Help ?

This should be a 1,8v output, how ever the output reaches 0.4v and when its in circuit it drags the 3.3v down to 3v then the tv shuts down, also it gets very hot. Something on the output side of that is shorted but its not the Hdmi chip its something else but what ? This is one hell of a crap shoot haha.

**ReeceyBurger123** · 10-28-2015, 02:15 PM

Re: 17MB35-4 3.3V Shorted Help ?

Anyone, I cant find out why the 1.8v section is shorted ??

**ReeceyBurger123** · 10-28-2015, 02:29 PM

Re: 17MB35-4 3.3V Shorted Help ?

Found by using a spare Mainboard that the 1.8v from that regulator drives the hdmi chip and its respective drivers so something in that section is still short.

**tom66** · 10-28-2015, 02:48 PM

Re: 17MB35-4 3.3V Shorted Help ?

Could be one of the ESD protection networks or the EDID EEPROMs.

**ReeceyBurger123** · 10-28-2015, 03:12 PM

Re: 17MB35-4 3.3V Shorted Help ?

Hmm the ESD is all good for the Hdmi processing area took off all the diodes and caps. Where are the EDID Epproms on these boards ?

**tom66** · 10-28-2015, 03:37 PM

Re: 17MB35-4 3.3V Shorted Help ?

Will be adjacent to the HDMI ports in most cases.

**ReeceyBurger123** · 10-28-2015, 03:49 PM

Re: 17MB35-4 3.3V Shorted Help ?

Ok will have a check cheers Tom.

**ReeceyBurger123** · 10-28-2015, 04:22 PM

Re: 17MB35-4 3.3V Shorted Help ?

Not those Epproms going to put this aside for a few days as im about to throw the whole lot out the window lol, will let you know if I find anything else.

**ReeceyBurger123** · 10-31-2015, 05:17 AM

Re: 17MB35-4 3.3V Shorted Help ?

Well some sad news, I fixed the board it was bad soldering on my part. I have improperly soldered a very small MLCC which I had shorted its pads to ground and its part of the 1.8v section, seems good doesn't it ?

Well, after powering the tv on I soon discovered that the Lcd glass is cracked, there are several spider web type cracks on the glass causing no image what so ever. This would have been done by the owner. So a whole bunch of crap shooting later and its trash anyway.

Thanks for the input chaps at least now I can make break even and make a bit of profit by selling the boards on ebay. This was a cluster fuck but ohh well

**tom66** · 10-31-2015, 07:17 AM

Re: 17MB35-4 3.3V Shorted Help ?

Could you see the cracks with the power off? I always check TVs with a light, and I can see cracks easily.

**ReeceyBurger123** · 10-31-2015, 07:56 AM

Re: 17MB35-4 3.3V Shorted Help ?

I never checked Tom tbh and no its not an easily visable crack. Ohh well got 5 more other 32" to fix so will get on with them.

17MB35-4 3.3V Shorted Help ?

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