Mac Classic analog board fault

[falen6]

Another stupid problem.
Just recapped the analog board out of my classic
When i first powered it up I got a wavy chess board display
after a minute or 2 I noticed the 'wavy' display was not as wavy
waited a bit more and it started to chime
it eventually boooted up perfectly

I plugged it out for the night and took some voltages today
+ and - 12 volts are good and steady

But the +5 volts starts out a 4.32 volts.......... as i leave it on i see the 4.32 volts slowly climb up and up - when it gets to around 4.5 it starts to chime ........ after a few minutes its up to 5 volts bang on and the machine runs fine


I found electrolite under the 2200uf caps as i replaced them

I didnt have a 1uf 50 volt radial so i used a beed tantulam cap

I didnt have the 470uf 50 volt so i took it out , checked its value ( looked ok ) and put it back

i have rechecked all my work and everything is good ( as far as i can see)

just having no luck lately !!!

anyone ever have this before ?? - 5 volt starting way to loo and then slowly climbing up to the 5 volts !!!

 

[dochilli]

Recapped Macintosh Classic with checkered screen

Hello, I recapped a Classic with capacitor damage on the analog board a few weeks ago (logic and analog board). Everything worked fine for a while, but today this pattern appeared on my monitor. I managed to narrow down the problem to the analog board (I swapped it with another one and the Mac...

68kmla.org

 

[dochilli]

There are a lot of parts on classic AB that can be defect. Most often: DP3 and DP4 (1N4148), TDA4605, CNY17G, IRFBC40.

 

[falen6]

Thanks for that dochilli ......... that thread is covering the exact problem i have - lots of parts to replace and see if i can fix it

cheers