Sony KV-27FS17 blown line fuse
 

I've got a Sony KV-27FS17 that won't turn on. Looked inside and saw the 6.3A line fuse was blown.
The smoked out component as pictured below is probably why, probably dead shorted too. What is it? Thanks
Click here to look and see

That is a varistor. It's resistance varies with applied voltage. Protection thing. It will blow if excessive voltage is present on the primary side of the main power input.

If that's blown open, then I would suspect something else to blame.

https://archive.org/details/kv27fs13/page/n27/mode/2up

Everything else in the set looks good. Maybe lightning strike?

Metal Oxide Varistor A.K.A. MOV.
Almost always from lightening. To test set just remove it & try set.
If you are lucky it did its job & saved the set. If not the sky
is the limit !
Zeno:smoke:

Varistor measures 35 ohms. But honestly if the fix isn't as easy as replacing that one component I'd rather give the set away for free, it's not very valuable in my eyes

The varistor used in this set is a ENE271D-10A from Fuji Electric
Will this part replace it?
https://www.digikey.com/en/products/...1K101/10433494

Is not a very critical part, so a extra energy clamping capatibility will not harm, so is ok

Set works after replacing varistor and fuse :beerchug:

New problem. Testing the set further, I see something's up with blanking? Retrace lines appear and the screen throbs red when a dark picture is displayed.
https://youtu.be/KJzMDL4dsrM

Has anyone here seen this issue before? Again, I suspect the Red gun is turned up too high, but I really don't know. This is one of those sets that has a service menu that can be accessed with the remote.

I don't think the red gun is to blame. Red gun bad is usually too red all the time. This looks like a dance party.

Some component is faulty and causing that to periodically happen. That TV has lots of IC logic in it, so it's beyond my understanding of the signal path. Very tough to know if it's an IC that's on the fritz or there's some tiny SMD transistor that has a leg blown open or what.

I guess if I had to dive into it, I would start checking voltages and waveforms around the boards. You have the clue that it's effecting the red gun, and also that the condition is pulsed or oscillating. You might be able to find some waveforms that are pulsing with that condition, and that might help.

But I would put a time limit on it probably. Especially if it turns out to be an IC, you would be stuck trying to do SMD transplants without knowing if things will get any better. Could get really expensive really quickly, and take too much time.

Turns out the screen (G2) voltage was set too high on the flyback. Lowering it fixes the problem.
Now, I have to correct the picture geometry. It's those yoke shims that peel off the tube :D

Interesting. I wouldn't think that the G2 would cause some kind of strobing red situation like that.

I have had a bad flyback pot before, and that did actually cause flakey flashing, but it wasn't set wrong, it was loose inside and the slug would pop in and out of the pot and cause wildly erratic brightness levels. I had to replace it.

The fact that you got red strobing probably means your color background (also called bias) is set wrong. If the G2 was to blame, it's bringing up all colors equally, and it shouldn't have looked red like that. It's needs to be balanced.

https://crtdatabase.com/faq/crt-color-adjustment


And if you really want to dial it in
https://consolemods.org/wiki/CRT:CRT...20choose%20D93.

I will look into color calibration since I've already got this set cracked open, although it looks fine to me.
When adjusting the G2 on this set, there's a very sharp cutoff for when the red flashing is triggered. I lowered it until a black picture appeared fully black. The service manual shows a proper procedure for setting G2 but I kinda don't have patience to drag out my Tek 422 and make a voltage divider to measure the color cathode voltages

Color background is measured by displaying a black raster and bringing the G2 up to the point where you have a very dim color.

The dim color you see should ideally be a perfect very dark grey of the color temperature target you chose.

The red flashes suggest that you are seeing a very red dark grey, which is wrong.

The brightest parts of the raster are controlled by the drive pots, and controlled independently from the bias controls, so you can have "correct" colors in the brightest areas without having proper color bias.

This is a problem because you won't have proper colors in the regions between the darkest parts of the raster and the brightest parts of the raster. That's what is called "color tracking."