Macintosh 512k issues, need to replace, but what is the R39? No video, rapid chirping when powered

[JohnnyPhantom]

Hey everyone,
I just picked up a Macintosh 512k with its original power cable, keyboard, mouse for $100. I think it was a good deal. It was sold as-is/repair. When I power it on, I get no video or tone. I do get a rapid high pitch chirping. I already ordered a full capacitor kit for the logic board and analog board which are on their way. I opened it up and noticed a good amount of rust on the frame, but no board damage. The battery was removed before it did any damage. The battery holder is clean with no corrosion. When I power the machine on with the cover off, I see a highly suspect component. The R39 sparks and then gets toasty. It looks pretty burnt up, so I'll start with that and the caps and see if that helps. Only question I have for now is, what is R39 and where can I get a replacement? Also, on the R39 is there a certain orientation I need to install it (like a capacitor) or doesn't matter? The analog board is part number 630-0102

Thanks everyone!

 

[jajan547]

Uusually experience I've had with the 512k tells me that clicking is a bad flyback but could be a multitude of things. Turn off the lights and with the case off turn on the MAC id you see a purple glow the Flyback epoxy has cracked and is arching.

 

[retr01]

That must be a fun purple light show, @jajan547. Does that often happen if the flyback is in terrible condition?

 

[jajan547]

That must be a fun purple light show, @jajan547. Does that often happen if the flyback is in terrible condition?

Well the three I’ve had have had that issue and you can try epoxying over but it’s not necessarily always the issue.

 

[JohnnyPhantom]

Ok, I replaced R39 with my best guess of what the part is based upon the few scraps I found online, I replaced it with one of these... https://a.co/d/eIwmoBp now I have plenty! Good news is, the machine powers on, chimes/bings and that's it. I can hear the floppy drive kick on, but no video. I saw from here, https://www.reddit.com/r/VintageApple/comments/miwkam that if no video and you give it a bump on the side, "If the solder joints for the fly back transformer or video signal are broken then this technique can make the screen flicker back to life and (rarely) stay on."

So I guess my next steps would be to reflow all the connections and while I'm at it, since I ordered them, I'll replace all the caps. I do get the orange glow at the tip of the CRT tube inside and with the lights off and pitch black, I get no purple light show. So that all sounds good to me. The last issue I noticed (for now) is the power switch is arcing inside most of the times. That can't be good. I reflowed it's connectors but same thing. I doubt it, but is this normal? what would be the fix for that?