60PB690v

[thuss]

Hi

I was wondering if anyone can help me with this one?

The tv comes on but theres no picture.

All the voltages are fine on the psu i.e va is 55v and vs is 204v both are constant.

On the Z sus (photo three top connection block) the 18v is not there (its about 5v) .

On the ysus the vsc is fluctuating from 3v to 40v continuously.

There are no lights on the tcon or the main board.

(next step I was going to connect RL to 5v and disconnect the main board)

Any advice would be appreciated - Thanks in advance

[Hamie]

Re: 60PB690v

Common fault on these are 4 shorted igbts on the underside of ysus. A shorted or blown smd cap on the top buffer. And (sometines) an open fusible resistor.
Although I've need seen the resistor open or know it's position.

Try unplugging the buffers and see if vy stabilises.
There is also a see a pin marked vsc that connects the y-sus to buffers.

[thuss]

Re: 60PB690v

Thanks for the reply.

When you mention the vy - do you the 18v?

I did check the igbts but they read ok- but I was a bit unsure because they look like there on the same circuit??

If there is a blown smd cap on the upper buffer can I replace it or does it mean a complete new upper buffer?

[Hamie]

Re: 60PB690v

No vy sound be around -180

If you unplug the buffers and the y-sus gives a stable voltages then you. May only have a problem with the buffers.

Yes, Easy to replace the smd cap.

[thuss]

Re: 60PB690v

I removed the upper buffer -vy was in the 50v range (fluctuating). Removed the bottom buffer and reinstalled the upper buffer and the vy as you stated was 187v.

I was just wondering can I repair the bottom buffer (if the large chips are blown its beyond me) or is it a total replace of the bottom buffer.

Thanks again Hamie for the advice.

[tvtimmy]

Re: 60PB690v

Watch some youtube videos on how to test y sus buffer boards. Norcal has a good one.
You also should test all the smd capacitors on that board against the top buffer.

[thuss]

Re: 60PB690v

I did exactly what Norcal715 and runforlife on their buffer test,

I am getting no beeps whatsoever. I even increased the range but still no beeps (ohms continuity).

But I am reading short on three smd capacitors, one at the top of the lower buffer and the two caps which are above and to the right of the bottom chip.

One other observation I forgot to mention - when I installed the upper buffer with the ysus (vy was 187) I didnt really get a grey half screen across the top half all I got was loads of pixels.

[thuss]

Re: 60PB690v

Theses are the caps (circled in red just about visible) that are reading short but when I do the buffer tests - I get no beeps

Also I compared smd caps to the upper buffer there is no beep.

I increased the range of the multimeter (in ohms) still no beeps.

I cant get a buffer at the moment -I looked everywhere.

Anyone repaired one of theses buffers- or have I got a leaky chip thats not showing up whilst doing the test?

Thanks in advance

[Hamie]

Re: 60PB690v

That cap is a 4nf 50v

Change it out and solder a 4nf ceramic through hole to the pads.

[thuss]

Re: 60PB690v

Will do thanks

[thuss]

Re: 60PB690v

Can I use this KEMET 4.7nF Multilayer Ceramic Capacitor MLCC 50 V dc ±10% X7R Dielectric 0603 Max. Op. Temp. +125°C? (its at Rs)

[thuss]

Re: 60PB690v

Tv's working again - thanks Hamie you know your stuff (by the way I used a 4.7nf 100v)

[Hamie]

Re: 60PB690v