Recent content by redruM69

I've got a ROM 01 IIgs in that fails diags with error 03011500.  From what I can decipher, it appears to be a state register failure, bit 01, address 15.  Not really sure where to go from here though.  My gut tells me CPU or maybe RAM.   Suggestions?

Oh well hey!  Even better!  I didn't know it was updated.

@alaska360: Your Mac Portable battery v3.0 model has a couple of minor errors that can cause slicing issues, and a weak print.  2 of the 4 corners on your outer box have disconnected shells, which caused those 2 corners to print as if they are free standing. I fixed it.  STL download below.

I threw in the towel and shipped the board back to the customer.  There's a point at which the time/money spent on diagnosis and repair exceeds the value of the board, and this is WELL past that.  I was hoping to follow through to the end, but I have a stack of other repairs growing.   Thanks...

No shorts between traces, or vcc/gnd found yet. I did poke at the address and data lines with a logic probe.  All data lines show activity.  All address lines show activity, except A0, and A15-A19 are held low while powered.  They are not shorted to ground though. Is that typical behavior?

ROM has been swapped numerous times with known good.  Contacts are clean. I can give this a shot.  I haven't logic probed anything yet. This is my SE test rig.  Analog is in great shape. Yup, 4 known good SIMMs installed.  

Update.  All 6 RAM mux chips replaced.  No change.

My next hunch is the UI2-UJ4 mux chips.  Anybody concur?

I have an SE/30 board in for repair that I just cant figure out.  It's been recapped, and corrosion was minimal.  It shows the attached pattern.  No chime, although I do hear 2 distinct "clicks" from the speaker at time of chime.  All address and data line and other traces have been checked...

It's worth noting that although the Toshiba 74HC166D is a CMOS part, it appears to be TTL tolerant.  It worked fine as a replacement in my case.

ISSUE RESOLVED!  Techknight, you may want to add this to your notes. It appears that Texas Instruments SN74HC166DRG4 is NOT a valid replacement for the the 166 shift register @ UE8.  It causes the discussed artifacts. I swapped it out again, but this time with a Toshiba 74HC166D, and the...

Bump?

Also, I have tried swapping all 5 PALs with known good.

Sorry to dig up a dead thread. Techknight, did you ever find anything on this?  I have precisely the same video bug, but cant seem to figure it out.  Both VRAM's and UE8 have been replaced.  Tested all traces to and from VRAM.  I still get vertical stripes with a slightly abnormal disk icon. ...

Bump.