Recent content by TheMightyMadman

Thank you very much, I appreciate the support and encouragement, nice work getting yours working again :) I'm back working on my SE/30 again, trying to make any slow but sure progress. Here's where I'm at now: it's making a slow, immediate "death chime", and the video RAM isn't getting reset...

Hi all, I hope you're well :) I've been continuing with this SE/30 board as and when I can, but unfortunately I'm not making much progress. Testing with a known-good ROM SIMM and four known-good RAM SIMMs in the lower bank makes no difference - the machine gives a long "chime of death", and...

Hi again :) I've swapped the original IC back into UH7, with no change in symptoms. I also have some faster GALs on order. I've also tried some additional combinations of the various RAM SIMMs in the bottom four RAM SIMM sockets, with no change in symptoms. In case it's of interest to anyone...

Thanks Bolle, that's very high praise indeed, I'm glad you think so! :) That's right, I'm using a programmed GAL16V8D-25LJN at UH7, I should have been more careful when choosing the part speed. https://www.ebay.co.uk/itm/152267566575 I swapped all of the original PAL chips across to the new...

Hi all, A few months ago, I bought my first Mac SE/30 sold-as-seen on eBay, figuring I'd take my chances on the condition of the battery. I was unlucky this time, and the battery had bombed quite badly! The machine didn't make a start-up sound, and have horizontal stripes. The original digital...

Thanks for the advice, all :) It looked like the two modules had managed to work themselves out of their sockets on one side. With them cleaned and refitted, the Performa is showing 104MB RAM, and Mas OC 8 has been successfully installed.

Hi all, I've got my Macintosh Performa 6400/180 up-and-running after quite a bit of work (power supply rebuild, replacing dead IDE HDD with a CF card and adapter, replacing the non-working CD-ROM drive), and I want to install Mac OS 8 from CD. I have an original UK install disc, and although I...

R4 is indeed open-circuit - it's supposed to be a fusible resistor, probably 0.5W. I've ordered a suitable replacement part. https://www.ebay.co.uk/itm/141743281894

Some additional notes: The Macintosh G3 desktop appears to use the same (or very similar) power supply: https://www.eevblog.com/forum/repair/psu-repair-vintage-macintosh-g3-desktop/ I've done a thorough visual inspection of the board and top side of the components, but I haven't actually...

Hi all, The power supply has unfortunately died in my Macintosh Performa 6400 - it won't start up at all. It is a 150W unit, Apple part #614-0060, Delta model number DPS-150GB B. The PWM controller (TOP200YAI) had failed dead-short across all pins. I'm not sure whether this was the cause of...

Thank you :) It is a little on the dark side, I still have some tinkering with the controls left to do, I think.

Hi all, At last, success! The lack of video was caused by an intermittent connection on the crimp on one end of the white cable between the mainboard and analogue board. I've been going back over all of my own work, and I noticed that the replacement parts that I fitted for CR1 and CR5 were...

Hi all, I've been doing some more testing. C4 tests OK out-of-circuit with an LCR meter (30nF). L3 tests at 10.7uH out-of-circuit - I'm not sure whether this is correct or not, but it seems reasonable. L2 tests at 12.1uH (with slug out) and 44.2uH (with slug in) out-of-circuit - I'm not sure...

That's great! Very nice work indeed. I'm very glad that my tip helped out.

Hi all, I tested R1 out of circuit, and it seemed OK. It looked like it had been running hot, so I replaced with with a 1W part just in case, but no change. When cold, there is 0.4Ohm DC resistance across L3/R1 - does that seem about right? C4 doesn't seem open-circuit or electrically leaky...