Garbled screen SE/30

[Knez]

Hi!

My SE/30 have been running just fine for over a year after recap, new RAM (128MB), ROM-inator II, DiiMo and MacCon II ethernet.

One day I started the machine and got greeted by what's in the attached image as well as a garbled start chime.

My first thought was that the ROM-inator had somehow lost contact in the socket despite the paperclip I had in place behind it.

Tried fitting a new and more sturdy paperclip, but with the same issue. As a last resort I put back the original SE/30 ROM SIMM with the same result.

So what can be wrong? The motherboard has been recapped by a guy that works daily with repairing electronics and have over 30 years of experience, so I doubt that the issue somehow is connected to the recap job acting up.

Anyone got any idea? I miss coding on the SE/30  

 

[Bolle]

Broken address line to the video RAM muxes or one of the muxes is bad.

Just to be sure, it's still garbled with the DiiMO and MacCon removed, right?

 

[Knez]

Just to be sure, it's still garbled with the DiiMO and MacCon removed, right?

Yep. The picture is taken with everything expansion wise removed, even the SCSI2SD disconnected.

So what to do? I'm terrible at hardware and soldering etc.

 

[Bolle]

Hm, take a multimeter and the schematics and go over the address lines to check if they have continuity between CPU or PDS slot and the muxes UA8 to UD8.

It's going to be A0, A1 or A2 most probably.

 

[Knez]

Alright. Do you know where can I find the schematics?

 

[dochilli]

https://museo.freaknet.org/gallery/apple/stuff/mac/andreas.kann/schemat.html