Need help with my Macintosh Plus

[keelus]

Hello there! A few days ago I got a Mac Plus for like 40€, but it's not working (I knew that when buying it).
I've been looking in this and other forums, videos, manuals, and I can't really find the issue. This is what my Mac Plus is doing:

Normally, i press turn on button, and theres no chime nor screen signal. The speaker makes some repeating noises. Also I can hear a bit of electricity maybe? :

I read, that heating the capacitors could help with that problems, and so I did. Doing so, removed the speaker repeating sound, but the rest remaint same:

I decided to wait a bit and, when the heat got cold, suddendly there was chime sound, the speaker sound dissapeared, but the screen remaint black:

I waited like 20 mins and again, back to the beginning issue.




Also here are some photos of the analog and logic board. I would really appreciate your help!

Images in high res: ( https://imgur.com/a/SZrlR7t )
I can take more photos/videos if needed. Thanks in advance ❤️

 

[keelus]

UPDATE:
I re-soldered the the flyback transformer and a few pins that looked a bit strange/cracked. Turned it on again and same problem. But, when i heat the board, I got those lines:

Waited for a bit of time, turned it on again and it gave me a sad face! With the code 024000 and then 028000. Which I have no idea what means:

 

[GBaughma]

"Crunch" the socketed chips. If the chips are in a socket, push them down (you should hear a kind of crunching noise).
Often, on "vintage" computers that used chips in chip sockets, there would be a little bit of corrosion build up between the pins and the socket. Pushing them down breaks that loose and re-establishes contact.
Just a thought....

 

[keelus]

"Crunch" the socketed chips. If the chips are in a socket, push them down (you should hear a kind of crunching noise).
Often, on "vintage" computers that used chips in chip sockets, there would be a little bit of corrosion build up between the pins and the socket. Pushing them down breaks that loose and re-establishes contact.
Just a thought....

Hello! What do you mean by "Crunch"ing the socketed chips? (My english is not the best x) ) Thanks!

 

[GBaughma]

Hello! What do you mean by "Crunch"ing the socketed chips? (My english is not the best x) ) Thanks!

The chips that are in a socket, put the board on a flat, solid surface (like a table), and push down evenly on the chips. Only on the chips that are in a socket. You should hear a slight crunching noise, as the pins of the chips break loose from any corrosion. Used to have to do it all the time back in the 80's/90's.

 

[keelus]

The chips that are in a socket, put the board on a flat, solid surface (like a table), and push down evenly on the chips. Only on the chips that are in a socket. You should hear a slight crunching noise, as the pins of the chips break loose from any corrosion. Used to have to do it all the time back in the 80's/90's.

Ohh I see, I should do that on the LOGIC board? Will try that tomorrow.

 

[keelus]

[deleted]

 

[keelus]

Hello. I've just measured the voltage on the floppy port, and all I get is an oscilating voltage between 0 to ~3. It never reaches 0 and its not constant, but it seems that follows a pattern..? Also, the 12V one does the same thing but between 3 and 5. You can see better in the video, where I tested 5V:

What could that mean? Thanks in advance.

 

[keelus]

Hello! Yesterday I replaced the U3 optocoupler for a 4N35 chip, which seemed to fix the flup flup + no chime no video issue. Also, I've just recapped every capacitor on the analog board (except C1 and 2 RIFAs). However, there's no change before and after recapping.
I've just turned it on, got the chime (in a strange way, very loud/low quality?) and after a few secs, a different tone "flup flup flup" sound came back but very quickly, sounded like an automatic gun, stopped and instantly got the chime and I got video with the RAM code 020100 (also, I swaped the RAM positions from, example, ABCD to DCBA and the code now is 028000 which I still don't know how to fix). However, a few lines appeared in the screen.
I know the RAM is failing somehow (because of the code), could that be the issue of the lines? Or other logic (not analog) board problem?
Thanks!

 

[m1maverick]

First thing I would recommend is to replace all the capacitors on the logic board. They're likely to be leaking and should be near the top of the list to be replaced no matter if the Mac is working or not. Unfortunately, if they have leaked and the leakage is significant the electrolytic may have damaged other parts of the logic board.