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Sorry for slow reply. I had written a post-it note on the front saying I needed to start checking Diodes. Basically I went to sell this on as faulty and then decided I needed to wait until I had the time to do one more pass before giving up. Does anyone know a source of other common failures on...

I took a video - here - can anyone diagnose why? I've recapped both the analogue board or logic board. Anyone know what would cause it to do this? cheers

I retrieved it out of the bins!

I went back and re-inserted the RAM stick and it shorts again. I didn't yet have the time to dig out my box of RAM sticks but I've assumed the module is bad and thrown it in the bin!

Thanks for the nudge. I might not have gone back tonight without any replies!

Ok wow, I fixed it. I kinda lost track of everything that was going on but it seems there were two issues. C15 was a problem. I removed all the caps and replaced 3 times - I'm amazed nothing got hurt along the way. It didn't help I kept working back to C15 as the last cap I removed but for some...

Right. I took off this: And all the shorts disappear. I put it back in and all the shorts come back...

Oh no. I thought they might be shorted to ground but they don't appear to short to things like the back connectors and there isn't any other obvious ground point to test against. I suspect an IC has gone bad but that's way beyond my pay grade. I guess I'll go over it again to see if anything...

Hi Everyone I was working on a LC575 logic board and foolishly I didn't actually test it before I started replacing all the surface mounted caps. Anyway I finished my tidy job, put it back in the unit and it doesn't power up. I put in a color classic board and it does. So, I noticed that I...

Thank god for that, because Arkanoid was the first thing on my to-do list...

Ah, my mistake. Still a nice quick 68x machine!

I found a Performa 475 with a bluescsi HD which is a great little 030 machine with the same video jack on it, so I am going to compare the video on that to this one (and test the monitor). Also a handy 'mystic' upgrade if ever desired...

Ok so learned a bit about using the scope. There is definitely a lot happening on most of the video socket pins. I'm having trouble comparing them to a VGA output but they're definitely similar. I did successfully lock onto various pins on some of the mainboard's ICs and can see stable digital...

Right. I'll admit something now. I bought a £300 oscilloscope (Rigol DS1054) for this exact kind of troubleshooting, but I've never actually learned to use it. I thought it would be a case of probing the pins on a VGA connector (such as 1/2/3 for R/G/B or 13/14 for H/V sync) and then scaling to...

Sorry, I just realised the PSU outputs into an inaccessible place when switched on. Can I trace the voltages from one of the connector ports on the back of the case (like on a Plus)? Thanks

I'll check the voltages and de-oxit the video cable/connector and report back.... I do have an analyser but have no idea what I'd be looking for on the DB15 plug....

I think it just says on the bottom "Macintosh II video card". I pulled the 8 additional socketed chips off and - nothing. I pulled out another LCD monitor and tried all 3 adaptors i have with the nubus card in all 3 slots and - nothing. Basically, I think it's the nubus. I guess I'll wait for a...

Oh and also I have at least 3 of those HD15->DB15 adaptors and all of them do absolutely nothing...

I'm testing with both a period-fresh Apple 15" Multiple Sync display as well as one of those dip-style VGA adaptors to an iiyama LCD. Neither ever shows anything.... I have an older dell 4:3 LCD laying around, along with some other LCDs i thought I might try just incase both of these are duds...

Right, Ok times are a-changin'. I switched the ram around and now with 4 original SIMMs in Bank A I get a single, normal chime. Still no video with the card moved between all 3 bus connectors.... the plot seems to point towards the nubus being bad, but the cheapest I can find is 'untested' on...