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Problem solved! But the problem was all of my own making... there's no way I'm ever going to graduate out of "New Tinkerer" :( Turns out I didn't properly solder (or test) one of the 110ohm resistors on the BlueSCSI I put together - once I correctly soldered the resistor in place the BlueSCSI...

Thanks @jmacz - I've been reading your threads and this sounds like a great lead - the Mac II uses the 53C80 (but not 53C80E) so chances are high of something similar. I'll also check out the strength of some of my traces (VIAs) around the SCSI controller - the machine was quite corroded when I...

Heh… not an answer I was expecting - Cabbage Patch dolls were in vogue around the same time I suppose. Thanks for the heads up :)

I don't network any of my Macs either but for different reasons (although I've done some limited tinkering just for the hell of it). One of the joys of working with these vintage machines is that you don't have to worry about credentials or having the latest patched software - unlike every other...

Thanks Robin-fo. My BlueSCSI v2 is definitely jumpered for termination so I must have an issue with my SCSI ports/controller or BlueSCSI, as booting from the internal port only works with an external BlueSCSI (without card) plugged into the DB25 port. I'll investigate further.

Hi All, Does the Macintosh II require a SCSI terminator on the external SCSI port if you're running a BlueSCSI v2 on the internal SCSI port? I've not been able to find any clear guidance. Thanks, Devy.

Not exactly what you're after, but here's the problem... I just cleaned off the rubber bumper "tar" and replaced with some stripped sheathing off some old thick wire (kitchen oven). Tip: I got the rubber bumper tar everywhere first go so clean off with disposable tools, eg. paper towel and...

Oooh - I like Snooper, particularly how it shows the RAM test patterns and banks. And the benchmark tests are nifty too. And “BlueSCSI” is actually reported on the SCSI Bus Info. Thanks for the tipoff 😃

Wahooo! Sounds like you're home and hosed! I'm not familiar with Snooper - I'll have to check it out.

Oh wow - a scan of a manual hold be awesome if it’s got any Accelerator II info. Searching for PowerCache I did find these… https://archive.org/details/DayStarCacheCardManual/page/n29/mode/2up https://archive.org/details/daystar-universal-power-cache/page/24/mode/2up

Many thanks for the info @Melkhior, Saving has started saving for some 74ABT651 spares - Mouser has them, but not cheap. I relatively new to the game so tend to focus of power, reset, address, and data lines. But thanks for helping me understand the importance of the DS and AS - another tool...

Hi All, Long shot, but does anyone out there have manuals, schematics, PAL dumps, or any doco around the Daystar 33/030 Accelerator II? Searching the web I’ve found very little info - even Daystar’s Internet Archive pages are sparse. A couple of ads and tests in MacWorld March ‘89 are about...

Gah - You’re so close! Great find on those broken traces. Maybe there’s just one other little wee bad connection - flexing or pushing on parts of the board might help you find it quickly.

Thanks @blturner :) I'm quite chuffed. If I had to bet on your issue I'd bet on another broken trace - to quote Wall Street Pros when reviewing a bad quarter "where there's one turd, there's many". And trying to follow traces on the top side, under chips and slots, can be quite tricky. I...

Sooo… turns out I had a broken trace (DSACK0 - data strobe acknowlege) from the NuChip (22) to the GLU (59). These data strobe signals seem to be quite important in getting NUBUS, SCSI, etc going - will definitely be a higher priority to check in future. Took me a while to find but got there in...

You latest YouTube post using the IR camera was very timely. I can’t believe those temps - especially those when powered off!

Thanks JDW - it’s good to get confirmation that it’s a tricky task to get an optimal fit and that I wasn’t missing something major (I’m relatively new to electronics and retro repair). I went for the best ripple specced caps (EKXE401ELL5R6MJ16S) I could find and went up to 5.6uF from 4.7uF (plus...

Sitrep: PSU and House intact. It sure looks weird but everything fired up ok and I let it run for 5 mins or so. Got to fix brokern traces on the Mac II motherboard now... Thanks @JDW for your SE/30 Sony PSU recap where you drill holes in the board for the big caps - it gave me the confidence to...

Thanks Gerry. I’ve purchased the best specced caps I can find (12000 Hrs @ 105°C; 100 mA @ 120 Hz; 250 mA @ 100 kHz). I can’t find the ripple specs for the original but can’t imagine they would be better than the best available today - unless there was a different subclass of cap that use to...