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Major update: Macintosh Plus is working fine! :) After all it was ok since the beginning. :rolleyes: The problem was that since there was no startup bong, and the 4Mb RAM testing takes some seconds, I disconnected it before it ended the RAM test, to prevent "further damage". After...

Hi! @cheesestraws Thanks for the info. I have another donor logic board that I can use to swap components. I'll try swapping this chips. Is there a way to check them with an oscilloscope before swaping? Thanks!

Hi! Thanks for the advice and reference. I'll have to buy the EEPROM reader/writer to test. Either I'll buy or do a project like the one Ben Eater has on his Youtube channel Build an Arduino EEPROM programmer (youtube.com) (This is part of the fun :) )

Ok! I'll do that this weekend and post the high res photos. (I've already reflowed all connectors at the analog and logic board...)

Thanks for the helpful information. Not going to buy new ROMs yet. I'll recap the logic board and in the meantime I'll take the high res photos and post them here.

Thanks for the info. I probed CPU pin 15 (clock) with the oscilloscope and got the attached signal. Don't know if it's normal because I don't have another functioning mac to test. Anyone can confirm if this signal is normal?

Hi Hi! Yes I've tried with the floppy, keyboard, mouse and everything completely disconnected, but the outcome is the same....

Thanks! :)

Hi Thanks for the reply. Indeed I removed both ROM chips and RAM SIMMs. Cleaned all contacts with De-ox and contact cleanner. Same result. But, yes you're right, sometimes MAC ROMs can get defective and, after recapping the logic board, if the symptons persist, I'll go that way. It will be a...

Hi! It doesn't give the chime sound, neither the FDD moves. I only get this screen, no mouse pointer nothing. If I press reset it resets and goes to the same screen. I'm going to repac the logic board. The clock signal taken at CPU pin 15 is wavy at the low edge and perfectly square above...

Hi! It was equal before the analog board recap. I didn't do the logic board capacitors yet. I'm waiting for the new capacitors to arrive. Thanks.

Hi, I recapped my Macintosh Plus analog board with the Console% kit. When it turns on, the voltages at the FDD port are -12,14V +12,10 V and 5,01 V. There are no strange noises or hissing. It's completely silent. I don't get the turn on chime, neither the FDD seeks or rotates, although it has...