Subtle video noise SE/30

[SpocksBeer]

Wondering if anyone has encountered this before. My SE/30 exhibits some subtle analogue video noise on cold boot, which seems to clear up shortly after its reached the desktop, or at least reduce to the point of rarely being noticeable. It's a rolling distortion that seems exacerbated by or synchronised to disk access (well, BlueSCSI). I've attached both a video and a frame for reference.

This is a recapped and cleaned logic board, albeit manually and not with an ultrasonic. The problem follows the logic board (I've tested with another SE/30 LB with this PSU and AB, and it does not happen with that board).

Things I've not yet tried, but will get to, is giving it another wash. Or probably just jumping to replacing the logic chips around UE8.

Will update once I've attempted these, but just curious if there are others with similar experience and/or suggestions.

 

[croissantking]

Wondering if anyone has encountered this before. My SE/30 exhibits some subtle analogue video noise on cold boot, which seems to clear up shortly after its reached the desktop, or at least reduce to the point of rarely being noticeable. It's a rolling distortion that seems exacerbated by or synchronised to disk access (well, BlueSCSI). I've attached both a video and a frame for reference.

This is a recapped and cleaned logic board, albeit manually and not with an ultrasonic. The problem follows the logic board (I've tested with another SE/30 LB with this PSU and AB, and it does not happen with that board).

Things I've not yet tried, but will get to, is giving it another wash. Or probably just jumping to replacing the logic chips around UE8.

Will update once I've attempted these, but just curious if there are others with similar experience and/or suggestions.

I have seen exactly this issue on one of my SE/30s even after recapping the analog board. IME the rolling distortion (rows of pixels that jitter left and right, as in your videos) is a separate issue from the disk access interference.

I fixed the rolling distortion by reflowing the yoke connector on the AB, which had dry joints. Beforehand, like yours, mine would clear up after running for a while.

The disk access interference remains on both of my SE/30s, I haven’t found a way to reduce it.

Given my own experiences I’d like to persuade you that this is an analog board issue rather than a logic board one. I do understand you’ve tried different boards but I think you’ll find if you run another board for a while you’ll eventually see the same symptoms.

 

[Durosity]

Given my own experiences I’d like to persuade you that this is an analog board issue rather than a logic board one. I do understand you’ve tried different boards but I think you’ll find if you run another board for a while you’ll eventually see the same symptoms.

I'll second this. I spent forever troubleshooting an SE/30 board which had the same symptoms on 3 different analogue boards. I was convinced it was the logic board as they all worked fine with the other boards I had. As it turned out, all three of those analogue boards were causing the same problem.. but oddly only with that revision of SE/30 motherboard (the early one with the bodge wire).. just by complete coincidence I realised they all had the same issue with another one I acquired and was testing.

 

[SpocksBeer]

Ok, I'll spend a little more time swapping boards and reflowing things. I could have sworn I reflowed the yolk on this one already, but perhaps not. I've only got two of the mid-gen (I guess?) SE/30 LBs, so no factory bodge wire but socketed CPU, to test with. Could try my SE board too I guess.

I do wonder if the neck board in this one is a little cooked, as I think this is the unit that had the faulty AB with a hole near burned through it (I replaced the AB since I could not get the old one running reliably, there's another thread from a while ago).

I thought I was going a little crazy, but I think I can hear a little sizzle sound coming from somewhere in sync with the video noise. I wrote it off as how the LB was driving the analogue parts.

 

[Byrd]

Also check the continuity and quality of the harness going to the motherboard; have come across some where the corrosion has wicked through some of the wiring

 

[SpocksBeer]

Well, OK, I'm back on-board with it being an analogue board problem. I reflowed the yoke pins again, but it made no difference. So I swapped the logic boards over again, confident that the problem would follow it, but nope the "clean" LB did the same, but worse. This time there was a lot of screen shaking, sensitivity to tapping the analogue board and that video noise.

Thinking aback to the sizzling noise I heard, I figured it was coming from the flyback. So I re-reflowed those pins, but this time I actually cleared out the old solder and I realised I'd forgotten to touch the ground pin last time (naughty x2), and that fixed the sensitive video output. There was still some video noise though. I also replaced BU406, with no change. I then reflowed the pin for CR3 that's on the AB, and that *might* have improved things. Noise is gone, but I'm not sure it's not just that the board has "warmed up". I'll try a cold power on again tomorrow (heading toward winter here, so cold cold) and see if anything has changed.

Thanks for the help so far. @Byrd, the wiring harness seems OK, no signs of corrosion thankfully. Pins at both ends (plug and socket) also appear clean. Haven't, but should, spray some Deoxit in there I guess.