Recapped Analog Board Macintosh Plus Stuck at the First Screen

[Paulo G Camara]

To echo what @Phipli said - I would be very surprised if it turned out to be the ROMs. Not impossible, but there are more likely options. FWIW I've seen them wedge like this when either the SCSI controller or IWM are broken in ways that look "half functional" to the computer, but there may be other causes as well.

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!

 

[Paulo G Camara]

To echo what @Phipli said - I would be very surprised if it turned out to be the ROMs. Not impossible, but there are more likely options. FWIW I've seen them wedge like this when either the SCSI controller or IWM are broken in ways that look "half functional" to the computer, but there may be other causes as well.

 

[Paulo G Camara]

Major update: Macintosh Plus is working fine!

After all it was ok since the beginning. 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 troubleshooting and probing *** allot *** , seeing a video of a similar machine booting prompted me to try and wait some seconds after turning it on, although it didn't sound the startup bong.

Surprise, it started booting from the FDD normally.

The real problem is on the internal speaker. It seems dead. Probing it with the multimeter reads open circuit, instead ~65 ohms. Connecting an headphone to the speakers jack, I ear the bong, So the sound circuitry is working fine.

Just need to replace the internal speaker, which is annoying because I'll have to disconnect and remove the whole analog board again.

Thanks for the help.