No Power, Lost blue Light projection TV Sony Kpf43m91)

Thread Starter

Echo26

Joined Jan 13, 2021
14
I do have a Projection that has some hissing sound and I suspected it was either coming fbt or flyback transformer or the High Voltage Splitter. After turning on for 10 secs , it popped and it began to have no power. I dont no where to start specifically on testing but i have already check for any blown cap which I have seen one a 22uf ecap. Still trying to see any shorted trans. Just wondering if a 2sc5778 as well , does it really have a Voltage drop between emitter and base both neg and poss (rev position), i dont have a transistor tester so im using diode mode instead.

On the convergence board bound to the stk ic, 4.7ohms 1% tolerance seems to be on 4.5 ohms right now. Which is far from 4.65 ohms on tolerance rating. Just wondering if its needed to be changed. There is a crack as well on the HV Splitter. Its bound on the gutter for the lead going to the flyback. The gutters for the leads going to the crts seems fine.
 

Attachments

Dodgydave

Joined Jun 22, 2012
9,951
That lopt looks cracked , can you swap the Blue with Red say and see if it changes.

The transistor is a line output stage ,and will be driven by a pulse transformer .
 

twohats

Joined Oct 28, 2015
206
Nice pictures.
Is it damp or just dusty, a good blow-out wouldn't do any harm.
High voltages love to track.
Good luck..
 

Thread Starter

Echo26

Joined Jan 13, 2021
14
Nice pictures.
Is it damp or just dusty, a good blow-out wouldn't do any harm.
High voltages love to track.
Good luck..
Its not that damp, i just suspected its probably where the hissing and the pop came from. My C5778 transistor i think is blown, and has voltage drop already from base to emitter on forward bias., I wonder if that is the the reason, i need to replace it. My main concern is just the hv Splitter. Ill try to swap them oup. Do you have any schematic of those hv splitter.
 

Thread Starter

Echo26

Joined Jan 13, 2021
14
That lopt looks cracked , can you swap the Blue with Red say and see if it changes.

The transistor is a line output stage ,and will be driven by a pulse transformer .
I'll try to swap them, can you specify, is it the hv leads you mean?

Can i use as well the vacant slot to to the left of the splitter towards the flyback hv line? It has a cap and seems unused. I wanted to transfer the hv line from flyback to the outmost left slot since it has no crack there. Its very unlikely that I'll be able to replace it locally.
 

Attachments

Thread Starter

Echo26

Joined Jan 13, 2021
14
Yes swap it over to try.

Which one is the Blue connection?
Im not sure but i had it labeled, ill have to check it first but I guess it was the slot 2nd from the right. Btw do you know any software that can generate test signals for displays like cross hatch or monoscope.
 

Thread Starter

Echo26

Joined Jan 13, 2021
14
Big problem, seems like the unit is kot oscillating. NO POWER i mean Dead set , even indicator lights . Primary power supply is live, but standby 7v is missing. And relay line is only 4.5v instead of 7 v.
 
Top