Classic II EGRET question

[fit2page]

I am currently working on a Classic II logic board which has no sound and black screen. Analog board is definitely OK, so I am suspecting the EGRET chip. The VCC is OK, if there is no waveform on pin 3 and 4 of the EGRET (OSC pins), can I conclude that the EGRET chip is dead?

 

[bibilit]

Maybe not, the best option is to remove the Egret from the board, clean the area, put it back and see if something has changed.

The Egret is surrounded by several caps, most of them leaking all other it, so you are probably going to find juice under the chip.

Pin 3 is connected to one of the legs of Y1 (OSC), while pin 4 is connected to the other leg... you are right

pin 5 to 19 of the sound chip (chip) and pin 22 to 21 of the same chip (are those OK ?)

 

[imactheknife]

On most of my classic ii systems i have restored i have had to pull egret and sound chip to get sound working. Also other chips i had to pull too, depends on how much leakage. Do you have a hot air workstation?

 

[fit2page]

OK, two of the Classic II's are starting now. On the first the problem was a broken trace near EGRET. The other is starting up but still no sound. Failure was due to a broken connection of pin 51 of the 68030. I 'll try to re-clean the sound chip.