Classic II with weird pattern!

[bsod]

Hi there,

Recently got a Classic II, which sat outside for a number of days... I

let it dry for some time (about a week or so), before trying something

else.

After plugging it in, and firing it up, all I got was this:




No bongs, nothing... it seems the floppy drive is working, though, as

I heard its familiar sound.

This pattern is really weird... it's a mixture of checkerboard with

vertical lines... what could it be?

Thank you!

 

[porter]

This pattern is really weird... it's a mixture of checkerboard with vertical lines... what could it be?

Uninitialised memory.

When a Classic Mac starts up it

(a) first checks the size of memory and does a memory check and

( B) clears the screen using 0xAAAA/0x5555 giving the true 50% chessboard.

© Then the corners get removed as QuickDraw starts it's act, the arrow appears now

(d) then the flashing floppy while looking for a boot up disk,

(e) then a happy mac when it starts the booting.

Yours is right at stage zero.

 

[Unknown_K]

Check the RAM, wash the motherboard clean and dry.

 

[equill]

The Classic II has 2MB of RAM on board, about which you can do nothing but inspect for and remove corrosion products around the pins. It can also take two identical cards of 1MB each or 2MB or 4MB to give a maximum of 10MB. 'Check the RAM', as UnknownK writes, means remove and make sure that expansion RAM cards are identical; clean the SIMMs' edge contacts (especially given the Mac's recent exposure to the elements); blow out the SIMM slots and reseat the SIMMs carefully.

A careful examination of the board for leaked capacitor goo is also a worthwhile precaution. If you have to wash the MLB, do it before re-inserting the RAM. All of the Compact monochrome AIOs use system RAM for video RAM ('Vampire Video'), so on-screen gibberish gives you only one villain to deal with as long as the drive to the CRT is working. Keep in mind that washing off capacitor goo is a stopgap measure. Leaking caps must ultimately be replaced.

de