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Byte Knight

My SE/30 died!

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I was using my SE/30 today when a "lightning bolt" shot down my screen and then it went blank.  I turned it off and back on again but all I get is the fan - no boot chime.  I'm getting 5.0V at the external floppy port, so I'm assuming this is an analog board issue.  The Dead Mac Scrolls confirms this, and I've tested the barrel rectifier at CR2 and the transistor at Q2 which seem good.  It looks like the next step is replacing the flyback transformer.

 

Should I do this or replace the capacitors on the analog board next?  If I need a flyback where can I get one?

 

Thanks in advance!

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I don't have the p/n on hand (mobile) but I have seen them and they aren't cheap.

 

Hopefully someone chimes in with the part number—Here's the thread post about numbers:

 

Edited by jessenator

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I've got the part number (157-026C Flyback) and they go for $99 on ePay.  But I don't even know for sure if that's my issue.  I think I'll clean up the solder on the flyback and replace the capacitors and see what shakes out, unless someone has a better idea...

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just a couple years ago they were only maybe 10 to 20 bucks. the demand probably sent the prices soaring through the roof. 

 

The "lightning bolt" effect you saw was a sudden loss of scan voltage without the beam killer circuit activating. Aka, the horizontal stage failed in some weird way. Or even the power supply's 12v rail disappeared. 

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So I replaced all the caps and the flyback on the analog board, and it worked for a couple of minutes before it died again - nuts...  There's now a hissing noise, and DMS suggests testing the barrel rectifier at CR2.  I get continuity through the barrel rectifier for about 2 seconds, then the ohms start climbing and then my multimeter overloads to 0L but no continuity sound.  Does this mean it's good or bad?

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the initial failure wasnt resolved that took out the first flyback. So I would hate to think about this, but you may have taken out the 2nd one. 

 

Not sure what the Hissing sound your describing is, could be many things. Could be diodes, capacitors, anything on the horizontal section, Up until, and including the sync gate logic IC. Without a scope, no way to know what the horizontal drive signal looks like to know if its correct or not. It has to be chased through the stages to find out where it gets screwed up. 

 

Because "hissing" means noise, and ALOT of it... 

 

Also a broken, gone to air CRT will do that too, but it would be more arcing than hissing. 

Edited by techknight

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