Replacing flyback in Trinitron

[DeathByBFG]

I have a Trinitron KV-1924 that, I believe, needs a new flyback transformer. I was able to procure one. But I am unsure how to actually remove it from the H STAT box it attaches to. The gray plug can be lifted but the red cable doesn't seem to budge. I've attached images. The service manual, from what I can read, doesn't specify how to do this.

[NoAffinity]

Looks like some soldered connections like any other flyback, and some mechanical attachments. You'll need to remove the chassis for the soldering. Is there a reason to believe there's something more to it than that?

[DeathByBFG]

Looks like some soldered connections like any other flyback, and some mechanical attachments. You'll need to remove the chassis for the soldering. Is there a reason to believe there's something more to it than that?

I'm not worried about desoldering the fbt from the board. I'm referring to the red cable that goes from the flyback to the HV Stat Block. I bought a replacement flyback from eBay (looks to be a reputable seller) but the FBT looks to be third party. Which I'm fine with. There's an electronics dealer that I purchased a flyback from for a different CRT and they had the HV Stat Block for my TV for sale on their site but no compatible FBT. The block didn't have the red cable coming out of it. And the fbt I purchased does. From what I've seen, and what I've read in the service manual, it looks like fbt and hv stat block are two separate pieces. But I can't find a way to separate them.

Edit: Hopefully reworded a couple things as I felt I sounded snarky. Not trying to come off like that.

[MKL]

It's very easy to remove. There's even a sticker with instructions right there. Can't you see it?

[DeathByBFG]

It's very easy to remove. There's even a sticker with instructions right there. Can't you see it?

Holy crap! No I didn't! LoL! I really didn't see that. Thanks for pointing that out. This should make my life easier.

[DeathByBFG]

I know I'm going to sound like a total dork having to ask this; but does anyone have any advice on how to actually twist the wire? I push down on it and I can feel and see it move. But I cannot twist. I'm hoping it's not damaged. It's been hard to get pics but hopefully what I did supply can be helpful.

[MKL]

First you pull the rubber boot back an inch or two. Then you push the cable in (there's a spring contact inside), twist it 90 degree (doesn't matter which way) and it comes off.

Can you post a pic of your replacement?

[DeathByBFG]

I did it! Here are some pics of the removal as well as the replacement.

[MKL]

That looks like a good product to me. I hope it will fix the TV but I'm must confess I'm sceptical as you need special tools to establish that unless there are obvious signs of failure (sparks coming off breaks in the flyback body etc.). I'm more inclined to believe it doesn't work because of other things but at this time without information I can't say anything.

[DeathByBFG]

Your skepticism if valid. So, when I bought this I knew it was broken. The previous owner heard a loud pop and sold it under the assumption it was probably a busted cap. I talked him down on the price and bought it hoping to fix it. Nothing seemed wrong visually. I did notice one of the fuses broke. I'm aware that what I did next was not the smartest thing to do but I honestly didn't really care that much. I caved to my morbid curiosity. I replaced the fuse with what I thought was an equivalent fuse. I turned the TV on and actually got a picture and a light on the channel tuner. But then smoke started pouring out of the TV. So, I turned it off and unplugged it. I double checked the new fuse with the old and the new one had a higher amperage rating. So it didn't trigger. I still didn't see anything component that looked like it started to burn or smoke. However, the FBT looked really sus when I got it. There was rust on it and a couple of other oddities. But, I did notice a dime shaped, rough, black spot on the side of it. Like it was charred. That lead to me thinking it is the FBT. I checked some of the components in the area of the fuse, the power supply and the FBT and nothing measured off. But I admit I may have missed something or may have mis-measured. I did order proper fuses. I'll do another cursory check of the components before plugging everything back in. I'll probably take the TV outside and turn it on in case it becomes a hazard.

[MKL]

I couldn't find a manual for your model. I'm using the schematics of the KV-1946 which seems to have an identical chassis.

The flyback needs +135VDC on pin 4 of the primary side to work (of course it also needs the correct drive pulse from the HOT collector on pin 5). This voltage line comes from the output of the bridge rectifier (D601/602/603/604) and it is fused with F602 (1.25A). Is it this fuse that blew? Or the AC one (F601 5A)?

Assuming it's F602, a shorted part on the 135V line (C519, C609, IC601) or on the HOT collector line (Q901, C901, C547) is what could be causing the fuse to blow.

With F602 off circuit, measure the resistance to ground (e.g. pin 11 of the flyback or negative side of C519) of pin 4 of the flyback (where the 135V goes to). Low resistance points to a problem with the above parts.

A light bulb test before turning on the TV with a new fuse is recommended. Pin 4 of the flyback desoldered from its pad and bulb and voltmeter connected to the fuse (and ground). If the bulb lights up and voltage is in the correct range you can resolder pin 4 and proceed but only if there is no short/low resistance to ground.

[DeathByBFG]

Thank you for the information! I can send you the manual if you'd like to review it.
But yes, it was the F602 fuse that broke. I'll check those components before getting too crazy.
I've never done a light bulb test before. I assume I need to attach a wire to pin 4 to the light bulb to start?

[MKL]

The bulb is a dummy load that replaces the flyback/horizontal deflection circuit. So you need to separate the 135V line from the flyback (e.g. by sucking solder off pin 4 of the FBT or lifting an in-line jumper if any). Once you've done this, you attach the bulb and meter to a point in the 135V line that has continuity with the desoldered pad of FBT 4 and F602 seems to me the most convenient point. The connections can be done with croc clips.

An unrelated example of this test:

https://postimg.cc/5YXXBNdV
(In this case the 145V line was separated from the flyback by lifting one side of that resistor)

[MKL]

I've edited the relevant parts of the schematics you sent me and they're very close to those of the KV-1946 I was previously using. The bridge rectifier is a single package (D601) so no discrete diodes (D601/602/603/604) and C609 and C547 are not present.

https://postimg.cc/BjWFzrkM

The rest is the same. If something is not clear, ask.

[DeathByBFG]

Awesome! Thank you. I'm going through it now. I definitely have low resistance on the negative of C519 to ground. That's with and without the fuse in the circuit. For the life of me I cannot find C901 though. I did learn Q901 is screwed into the metal that the board is attached to. But I don't see a capacitor attached to it. I'm still going through everything else. I want to say C519 is probably bad but I think that's an erroneous assumption right now.

[MKL]

The negative of C519 is ground so obviously there's zero ohm resistance to ground there. It's the positive of C519 (which is on the 135V line) that should be measured to ground. And if it's easier, measure across the collector of Q901 and the heat sink. C901 may be the cap I indicated:

https://postimg.cc/jC7Wj5JZ

[DeathByBFG]

Yeah, that is a cap actually. I had a hard time reading it and performed a Google reverse image search on it. The results were something other than capacitor. Just did it again with a better picture and sure enough, it's a cap. What's interesting is that the service manual says it's 1.2KV but the cap has 1.5KV on it.
https://postimg.cc/62C5KMH0

[DeathByBFG]

So good news, I hope. After working through your suggestions I never found a shorted component. I also checked some components around the general area and everything was within spec. So I decided "F it" and replaced the FBT. After putting it all back together I hooked up my SNES and it worked. The TV worked as it should. I didn't stress test it for hours. But I played a good amount of SMW, SMB1 and even let the opening animations for Super Mario All-Stars run. The TV powered through like a champ.

There are still some problems to address with the TV.
1) The sound needs to "warm up" before it stays at the level I set. I set the volume, it goes to that level, then it gets quiet and eventually comes back to normal.
2) The channels on the TV set need configured. I have my SNES set to channel 3 but I have to put the TV on channel 7 for it to work.
3) The knobs to adjust the hue, color, etc. are not very responsive. If I fiddle with them to make better contact then they adjust. But it's a pain. I just use the switch for auto-color for now.

These are problems I'd like to address but I think I'm ready to move on to other projects for now. I have two other mid-90s Trinitrons that need fixed. One is giving me the 2 blinking LED error code. The other has a wavy line.

Thanks for your help everyone!