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Yup, was thinking about that too, assumed such level of sophistication was not present but that may be wrong.  Found old schematics so soldered in EHT back and measured voltages. Can't find any datasheet about LSC1178B but it gets RGB/sync signals in and outputs RGB + drives HOT so it may well...

Machine is macintosh LC III and MMU is mentioned . The Macintosh LC III hardware, however, always operates in 32-bit mode. The memory management unit (MMU) inside the 68030 works with Sonora’s memory controller to map 24-bit addresses to their 32-bit equivalent. What is kind of getting my...

Hard to tell if EHT is shorted with just regular multimeter. Any way to check for EHT startup safely? Checked HOT transistor and it is good no short and tested after de-soldering. When I turn the monitor on I hear de-gaussing loop working  but no image, not even background (white) despite...

No, /BERR is flipping too. Mind I only have two channel scope but it almost looks like it operates in 8 bit mode read (/DSACK1 high all the time) which points me to either faulty ROM or RAM - but obviously not sure if I understand init sequence well. What I understood is that upon reset and...

Hi, Would anyone know most common reason for /BERR to be asserted for LCIII 68030 CPU? Obviously no boot, no sound, no picture but there's life on the bus. /HALT /RESET are not asserted, I see on oscilloscope activity on ROM data pins as well as CPU/DRAM R/W pin. Without logic analyser no...

Hi All, Anyone knows where to buy a replacement for EHT for this monitor? There's no high voltage output (screen is not highlighted) and upon inspection EHT has white residue on it. Probably cracked/epoxy leaked somehow. Checked caps all are good, Measured HOT transistor, transformer seems...

Hello All, Anybody knows where to find this MCU which has Apple programming on it? I am working on a very tired board which suffered from battery damage etc. - no boot of course. Aside from all sorts of issues and a need to replace dead CPU (yup-it looks like) it probably has bad 341S0851 chip...