Apple 2GS Serial Issue

[rcrook9190]

I am having issues with the serial ports on my //gs. I am getting random characters being generated somewhere on the logic board itself.

I want to find a Zilog Z8530VS SCC chip to see if this is where the issue lies. But I am having problems finding a source for this chip.

My question is does anyone know where I might source one. Be it in the form of a spares/broken logic board, a source of second hand ones, or even possibly one of the older Macs may have used the same or compatible chip hence salvage one from a spares Mac logic board.

Regards


Randall.

 

[Kai Robinson]

Is it a DIP, or PLCC chip? Because ZiLOG still sell these, new.

PDIP: https://www.mouser.co.uk/ProductDetail/ZiLOG/Z85C3008PSG?qs=qbjGrYYs/skQJuc71lxRTQ==
PLCC: https://www.mouser.co.uk/ProductDetail/ZiLOG/Z85C3008VSG?qs=z96q/FFR6qb6cf17DanQqQ==

 

[rcrook9190]

Is it a DIP, or PLCC chip? Because ZiLOG still sell these, new.

PDIP: https://www.mouser.co.uk/ProductDetail/ZiLOG/Z85C3008PSG?qs=qbjGrYYs/skQJuc71lxRTQ==
PLCC: https://www.mouser.co.uk/ProductDetail/ZiLOG/Z85C3008VSG?qs=z96q/FFR6qb6cf17DanQqQ==

Thank you. Its a PLCC. So the Z85C3008VSG will work in place of the Z8530VS? Im not particularly smart when it comes to this sort of thing.

 

[Kai Robinson]

Yep - pin compatible, the only difference is the fact the current chips are made with the CMOS process, instead of HMOS or NMOS. It's a direct replacement part.

 

[rcrook9190]

Yep - pin compatible, the only difference is the fact the current chips are made with the CMOS process, instead of HMOS or NMOS. It's a direct replacement part.

Awesome. Thank you very much Kai. I will order a couple.

 

[rcrook9190]

Didn’t help. Still getting random garbage in PT3 on both printer and modem ports.

I have now replaced the both 26LS30s, both 26LS32s and the Z85C3008. And I ams still getting garbage on both ports with nothing plugged into either of them.

I have been over the board multiple times with a magnifying glass and can see nothing.

I have checked the circuit diagram and if some one can confirm what the RC4300s are I will try to source replacements for them too.

Any suggestions would be appreciated.