NEC FS5197 TV, Blank screen, sound okay

If EHT and heaters are ok, the problem must be manifesting on cathodes or grids. (Emission so dire you cant see a thing is pretty unlikely, but I have come across it once.) I dont see that theres anything to suggest other than metering those and working back from them. Of course the cause may be far away from the cathodes, possibly as far away as in the tuner. Without a cct diag youre going to have a hard life!

NT

And what is Q681 "bingo"?

is it the HOT or what"

If EHT and heaters are ok, the problem must be manifesting on cathodes or grids. (Emission so dire you cant see a thing is pretty unlikely, but I have come across it once.) I dont see that theres anything to suggest other than metering those and working back from them. Of course the cause may be far away from the cathodes, possibly as far away as in the tuner. Without a cct diag youre going to have a hard life!

NT

"Frank" wrote in news:4533bd5d$ snipped-for-privacy@clear.net.nz:

Thanks guys but ----- A big sorry -- I forgot to mention that the on screen display is working fine. The crt and it's voltages are okay. The problem is in one of those multi-legged devices or in a switching transistor(s). Video In or TV just produces a blank screen. Setting the onscreen menu to display a blue background for no signal also produces a blank screen. I started poking around the transistors located around the tuner/video stage. Unfortunately as I said I don't have a circuit so it's a bit tough to find out where each stage is and what each section does.

TJB

So how do you expect to check the voltages and waveforms at all the key points if youve got no cct diag? How are you going to narrow the fault down until you find it with no such info?

NT

snipped-for-privacy@care2.com wrote in news: snipped-for-privacy@i42g2000cwa.googlegroups.com:

By asking in these newsgroups in the hope someone may have helpful info. Failing that get the data sheets of the various chips and work around them. Fixed a number of sets with no ccts, some problems are very simple to solve, others just time comsuming.

TJB