Mac SE/30 with strange SimasiMac - help needed

[uniserver]

Nice work!

 

[miniMOJOman]

Sweet! Back from the grave, good job!

 

[uniserver]

so just to help out future people,  you ran a wire from 

ASC pin 41

to

GLU pin 77

looks like if that one goes, then so could this one too.

GLU pin 74

to

ASC pin 42

Whenever I get scratchy sound, I always take ASC off, scrub the pads really good with flux and wick,

Sometimes i will scrap the SM a little from the pad if i see some rot.. just to make sure there is a good connection between the pad and the trace.

flood all the pads with solder and flow the chip back on and most of the time that fixes fizzy sounds issues.

 

[bobo68]

Yes, I ran a wire from ASC pin 41 to GLUE pin 77 (the A0 address line). I'm relatively sure that the failure of this line can be attributed to the ASC's pin/pad because the trace on the board to the GLUE is short and looks very good.

 
A1 (pin 42 ASC to pin 74 GLUE ) was still intact. I did not want to resolder the ASC because my SMD skills are limited. I'm actually quite proud to have soldered in the small tantalum SMD capacitors and the wires.   We'll see if the cleaning was enough to stop A1 from failing.

On top of that I connected UD8 pin 4 to UK6 (Video ROM) pin 10 which brought video back to normal. And I had to connect the plus side of C6 to UB11 (Sony sound chip) pin 7 because the plus side pad of C6 was gone.

 

[uniserver]

So in short 68kmla helped save the day, another happy Mac back in service, successfully liberated.

So just a1 and a0 go to the glue, The other address lines to the ASC could also cause scratchy sound... But those lines would need to be ran from other I/C's... What ones look like a safe bet? looks like those other address lines connect up all over the place.... A2+> etc. I ask because I am building documentation for shot gun fixes for the se/30. I mean cap goo can really only cause so much rot, in only so many places.

 

[uniserver]

Right now I am mastering the art of flux less solder fixes, pad to trace, solder most of the time has an undesirable trate of not flowing with out flux, well if you are careful this can be a good thing when fixing bad pad trace connections under the IC. . It's defiantly something that takes some practice that's for sure, Just the slight bit of flux and your connection is now lost.

 

[bobo68]

So just a1 and a0 go to the glue, The other address lines to the ASC could also cause scratchy sound... But those lines would need to be ran from other I/C's... What ones look like a safe bet? looks like those other address lines connect up all over the place.... A2+> etc. I ask because I am building documentation for shot gun fixes for the se/30. I mean cap goo can really only cause so much rot, in only so many places.

I can't tell from the schematics. GLUE and ASC are not on the same page of the multi-page document so it is not clear where the traces run exactly.

ASC has A0 - A11, GLUE has A0, A1 and then from A13 onwards (but not all lines, e.g. A18 is missing).

Furthermore ASC's A1 and A2 seem to go directly to UG12 (8530 SCC).