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Looking for a flyback transformer for an Eizo TX-C7 MA-791 17" CRT

retrotechrestoration

retrotechrestoration

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Joined
Oct 17, 2022
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Tallahassee, FL
I just saved this magnificent component input Eizo Flexscan TX-C7 MA-791 from the local e-waste...good news, the tube works and the board looks great...the bad news, it sounds like the flyback is shorted. (Turns on...perfect picture...systemic high voltage crackling heard while the picture flickers...then it blows the 5A fuse in my isolated A/C power supply.)

Anyone have any leads on possibly finding a replacement? (photo shows the flyback model numbers)
 

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If you can hear the flashover, are you sure the flyback is bad? Have you run it in a dark room with the back off to look for the spark? It could just need some cleaning...

Don't mean to throw you off your tracks, I just know FBTs don't typically go bad.
 
Bentendo64 said:
If you can hear the flashover, are you sure the flyback is bad? Have you run it in a dark room with the back off to look for the spark? It could just need some cleaning...

Don't mean to throw you off your tracks, I just know FBTs don't typically go bad.
Click to expand...

Good intuition...I've been discussing this mostly over on the badcaps forum (https://www.badcaps.net/forum/troub...k-transformer-for-an-eizo-tx-c7-ma-791-17-crt).

I've tested the degauss coil and circuit and spent last night tracing the entire power supply circuit. Unfortunately, it seems like the culprit may be the main transformer. :(
 
I've been working on electronics for many years, and I have yet to see a switching power supply transformer fail. I'm not saying it can't happen, it's just incredibly rare.

Since the fuse is now blowing instantly, something must be shorted. You need to check all the power transistors, and power diodes in the power supply for shorts. You can do that without removing them from the circuit. Also, check the horizontal output transistor. You can start by replacing the fuses, and measuring the resistance across the AC line input, then keep going through the circuit until you find what's shorted. Don't plug it in again until you find out what's wrong since you can cause more parts to fail.
 
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