How to test flyback transformer with multimeter?

[caliban10]

Is it possible to test a flyback for a Color Classic using a multimeter without removing it from the analog board?

I've replaced most of the caps on the analog board but I'm trying to determine if I should keep going & replace the rest of them or I shouldn't bother because the flyback's dead.

 

[Elemenoh]

FBT coils cant be tested with a typical multimeter but can be with a ring tester. Search for blue ring tester. There are kits you can build and assembled ones pop up on eBay now and then. It’s not that likely the FBT is bad on your CC though. What’s the symptom You’re experiencing?

 

[caliban10]

No video.

Full history is:
- obtained Mac CC
- recapped logic board (which has booted ever since)
- recapped 13 caps on analog board as per https://recapamac.com.au/macintosh-cc-analog/
- it worked for about a year with no problems. only booted it occasionally.
- restarted after a long time and it boots but display is black
- recapped more and more of the analog board caps including the big 330uf/400V without it fixing the display.

So now I’m thinking that I should verify that the flyback is working before I recap the rest of the analog board. I’ve recapped 23 out of 47.

 

[Elemenoh]

What happens if you give it a tap when powered on? If you get a flicker of video maybe you have a broken solder joint. Have you already checked/reflowed the large joints like those on the FBT?

 

[Elemenoh]

BTW it looks like the older Blue Ring tester kits are maybe no longer being made. There's a more modern tester based on a microcontroller for sale here, though I can't vouch for that site since I haven't ordered one myself.

EVB METERS

Bob Parker Meters from Portugal

evbesrmeter.pt

YouTube video demonstrating it is here which links to the site above if that makes you feel any better about ordering.

 

[caliban10]

Well thanks so much for all that info. I'll pull the analog board out again this week and check all its joints. I haven't reflowed any of its connections yet.