Mac 512k issues

[tf 85e3]

I just got this and when i power it on an immediately turn it off then on it does this for a second and goes away i think its the caps.

 

[JC8080]

What happens if you just power it on?

 

[bibilit]

The 512k has no issues with caps. More an issue with ROM or RAM

 

[mmmlinux]

Isn't that just junk in the vram before it gets initialized? you normally don't see it when you just turn on the machine because the display isn't warmed up enough yet to make a picture.

 

[tf 85e3]

What happens if you just power it on?

If i just power it on it doesnt show it when i quickly power it off then on it does

 

[cheesestraws]

Isn't that just junk in the vram before it gets initialized?

Yes.

If i just power it on it doesnt show

This is probably because the CRT hasn't warmed up yet on a cold boot. It goes from this to a normal boot screen?

i think its the caps.

very unlikely in a 512k IMO

 

[Builder68]

The symptoms you're describing are consistent with bad RAM

 

[Builder68]

Even though less frequent, ROM sockets on a Macintosh 512k can become corroded after nearly 40 years, which can sometimes cause vertical bars at startup. To address this, thoroughly clean the ROM socket contacts with DeoxIT contact cleaner spray and then carefully reseat the chips.

It's worth a try since it's a far more simple job than desoldering RAM chips on that motherboard.

 

[Fred1212]

Looks like ROM chips may be swapped around and something else as well causing half screen.

 

[mmmlinux]

is it just doing that when you hot restart it? does it boot normally after?

 

[tf 85e3]

is it just doing that when you hot restart it? does it boot normally after?

Idk what a hot restart is but quickly shutting it off then on shows it but if i turn it off wait a second then turn it on it doesnt do the vertical bars

 

[mmmlinux]

but then it goes away and the system boots normally?

 

[tf 85e3]

but then it goes away and the system boots normally?

Yea if i let it sit for like 15 25 seconds or so it doesnt do that so probably just turning it on and off quickly