Flyback transformer

[petieken]

I have ordered new caps for both my Wells Gardner 20K7201 monitors a few days ago (Sagaia cab). I was reading about the WG K7000 series on KLOV and there was a post about the flybacks, apparently the flybacks with white screen & focus knobs are the 'old' ones and are very prone to failure (I have this type). The recommendation was to replace this type whether it was working or not. What are your opinions on this?

Before I pulled the chassis I had noticed that 1 screen sometimes went off for 1-2 seconds and turned back on now and then. Could this be the flyback starting to fail?

For the replacement, where do you buy these things in Europe? I found this 'HR' brand via Starcab, but Starcab only has flybacks for Hantarex chassis. So I went to HR website directly and entered the part number from the WG service manual (from the WG website). Result was this: http://www.hrshop.es/index.php?command=search&by=tvmonitor&q=053X0528&x=0&y=0

Does anyone have experience with this brand flyback? Or can you recommend me another reputable brand?

[italiandoh]

I have ordered new caps for both my Wells Gardner 20K7201 monitors a few days ago (Sagaia cab). I was reading about the WG K7000 series on KLOV and there was a post about the flybacks, apparently the flybacks with white screen & focus knobs are the 'old' ones and are very prone to failure (I have this type). The recommendation was to replace this type whether it was working or not. What are your opinions on this?

I wouldn't if it's working. I have 20+ years old flybacks working perfectly.

Before I pulled the chassis I had noticed that 1 screen sometimes went off for 1-2 seconds and turned back on now and then. Could this be the flyback starting to fail?

It sounds more like a bad contact, either a cold solder joint or oxidized contact or a dirty one. If I were in your shoes, I'd have dismounted both monitor electronics, clean everything (electronic, contacts, tube), then proceed at a close inspection of all contacts and power solder joints. Then reinstall everything and see how it works, making sure that all the pots are properly adjusted.
A cap kit could be needed or not, it depends. Surely it's the most easy thing to do if you don't know monitors.

For the replacement, where do you buy these things in Europe? I found this 'HR' brand via Starcab, but Starcab only has flybacks for Hantarex chassis. So I went to HR website directly and entered the part number from the WG service manual (from the WG website). Result was this: http://www.hrshop.es/index.php?command=search&by=tvmonitor&q=053X0528&x=0&y=0

Does anyone have experience with this brand flyback? Or can you recommend me another reputable brand?

HR is a top brand. They make replacement flybacks for many TV and monitor models. I've used it all the time.

Matteo

[petieken]

I have some basic knowledge about electronics, just not with monitors . My main class in school was electronics, and 90% of my non-school electronics experience is with audio amplifiers.

For the small price that caps cost I think it's better to replace them. They're going to fail eventually, all electrolytics do.
When I'm replacing them I'll check for cold joints and reflow if necessary.

[level42]

You know, I've always been in the camp of "replace all electrolytic caps even if it's only preventive, but lately, I'm not that sure anymore.....

See, some of my monitors are SO good, they look like brand new. F.I. the Sanyo 20C (this is even older than the 20EZ model! ) in my Nintendo cap looks brilliant (Ok, I replaced the "fold-over" cap, but this one is RIGHT next to a transistor heat-sink).
Also more recently, the Berzerk machine has a G07 that looks like new after cleaning the screen and bezel. And it HAS been run quite some time because there _is_ some burn-in on the screen. I have no jitter, no shake, no bars, no weak colors, very good focus and convergence (although that has nothing to do with caps).
But all caps are original. And actually, I'm not going to cap-kit it. I decided to leave stuff that is working 100%.

I also did some measuring on power supplies with very old caps. There was virtually no ripple on them and ripple is what you should get when electrolytic caps start acting up.

I'm still in doubt though. I'm not saying it's all nonsense and I've seen plenty of bad caps after all those years (even on game PCBs). But I'm just getting some doubts wether it's _always_ a good idea to cap-kit monitors and other stuff.

[petieken]

Well, I'm doing a capkit because there _are_ problems with the monitor (the dark part on the second monitor, and a little color smearing on the first monitor). I'll see how it works out, I'm not going to replace the flyback until it fails though. I'm following Matteo's advice on this.

Your reply reminds me of the old phrase: "If it aint broke, don't fix it". I think I'm going to follow this quote in the future .

[level42]

Yeah, sure, if there are any problems in a monitor, caps are the second thing to look at/replace (after CONNECTIONS !)

[uncletom]

Regarding monitor problems such as you describe, I would check the solder joints under the parts that get hot. It is normal with old monitors that solder boils away, especially if the solder is not of good quality. Just apply new solder where you see dark areas under the chassi PCB, and also on parts mounted to heatsinks.

Ofcourse your HT transformer can be ready to die, or the HOT (horiz.transistor). Then if your problem is not fixed with new solder I would replace the HT transformer and the HOT.

Ofcourse a cap kit is also a good idea just to make sure.

[petieken]

I already checked the KLOV forums and my problem seems to be common with the WG K7xxx series, a capkit should solve it... I already have the caps ready, I just need a new soldering station because my current iron died a few weeks ago.