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Powerbook 140

macrumors newbie
Original poster
Apr 22, 2019
11
2
essex UK
after pulling my G3 to bits and harvesting the analogue board from it I can't visually see anything that has failed.

according to someone on YouTube they state if the Flyback is dead it could put a short on the horizontal transistor/circuitry and pull down the power rail, however when I measured the 26pin connector (on the left hand side tube front facing you) for voltage I DID get some kind of "Fluctuatey" voltage from Pin 23 through 26 and ground of course (Pin 18), but would that indicate something else?

I do not have another IMac to harvest working parts out of to test, and I would much rather fix the Parts I have on hand than buy new ones, That being said does anybody know of someone who is knowledgeable about Flybacks or CRT circuitry in the UK I could send the Board/entire computer to?

if anyone can measure the voltage from that 26 pin connector on their own mac that would be great and could assist me in determining if the Caps or the Flyback is bad.

Thanks for your time!
 

TheShortTimer

macrumors 68040
Mar 27, 2017
3,270
5,677
London, UK
after pulling my G3 to bits and harvesting the analogue board from it I can't visually see anything that has failed.

If you're able to share some images of the PAV board, there might be others who can give you a second opinion or confirmation on this.

I do not have another IMac to harvest working parts out of to test, and I would much rather fix the Parts I have on hand than buy new ones...

I'm also in the UK and I'm in a similar situation to yourself. My iMac G3/350 needs attention - I suspect that the PAV board on mine might need recapping (which I can do) and that the Flyback Transformer is failing but in any case it should probably be replaced anyway to be on the safe side. The FBT is either difficult to locate or where I've found them for sale, extremely expensive.

That being said does anybody know of someone who is knowledgeable about Flybacks or CRT circuitry in the UK I could send the Board/entire computer to?

Basically, all you need is an electrical engineer - they would possess the knowledge required to give it the once over and identify any issues. Unfortunately I no longer know of anyone in London/the South East who is in still in the field that I could recommend.

if anyone can measure the voltage from that 26 pin connector on their own mac that would be great and could assist me in determining if the Caps or the Flyback is bad.

My machine is packed away at the moment but I'll see if I can have a look when I get the chance. :)
 

Astro13

Cancelled
Nov 4, 2023
78
27
I have an DV SE that I got for free off of a friend, it’s been my little project so far, I think mine has an arcing fly back transformer… last time I checked working that close to the CRT has its dangers. If anyone has any experience with working around the crt and could tell me the chance of it imploding or shocking me to death, it would be nice
 
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