SE/30 analogue board fun

[VMSZealot]

Ohh kay.  So now my SE/30 is booting fine, and all seemed well.  But…

…the screen is rather dim (in fact, totally black until the brightness knob has gone past half-way) - and occasionally shimmys very slightly.  You wouldn't notice unless you were looking.  Damn.  Just when it all seemed to be going so well too.

I guess that the problem is with the analogue board.  Can anyone point me in the direction of a servicing manual for the analogue board?  Does anyone have any helpful hints on what I might need to fix?

Just to be clear, the SE/30 digital board has been repaired, the analogue board has had a light servicing in the past (when the fan failed), the digital parts of the Mac all work fine - the sound is loud and clear, scsi is fine (internally and externally), the network card lets it connect to my network and that all works perfectly.  This issue appears to be entirely analogue in nature.

 

[techknight]

Or its a weak CRT. it can happen. 

 

[jessenator]

If the analog board hasn't been re-capped, that's really just good due diligence for a machine this old at this point.

There is also the matter of adjusting the trim pots behind the paper(plastic?) white sheet with the indicators will show what adjustments can be made including: horizontal and vertical scaling, focus, and cutoff (sometimes called brightness in documentation). Cutoff is essentially a coarse brightness correction, and there are official documents on how to set that correctly, like this one: https://www.macrepaircentral.us/macintosh-se-30/video.html

But I would make those adjustments post-recapping.

Also, I can't speak to all of them, but some are adjusted with a flat blade tool (use plastic, NOT metal screwdrivers) and one of them (I think the vertical scaling) had some odd hex/allen shaped hole for adjustment. I just printed my own adjustment tools.

As far as re-capping the AB, I'd recommend JDW's video:

 

[VMSZealot]

Or its a weak CRT. it can happen. 

Ouch.  I hope not!  Where could I get a good replacement CRT from!?

 

[VMSZealot]

If the analog board hasn't been re-capped, that's really just good due diligence for a machine this old at this point.

There is also the matter of adjusting the trim pots behind the paper(plastic?) white sheet with the indicators will show what adjustments can be made including: horizontal and vertical scaling, focus, and cutoff (sometimes called brightness in documentation). Cutoff is essentially a coarse brightness correction, and there are official documents on how to set that correctly, like this one: https://www.macrepaircentral.us/macintosh-se-30/video.html

Thanks for the tip.  Now I just need to get the right caps.

 

[jessenator]

Where could I get a good replacement CRT from!?

As far as I'm aware, eBay, and occasionally the Trading Post on the forum. Most of the time, it comes in the form of purchasing a for-parts compact mac. Buying a compact (128k–Classic***) that's for-parts can be a risk, but it  can pay off as well. Very rarely do you see an NOS replacements, but the possibility exists at any rate. You could also create a WTB post in the Trading Post as well, if you haven't found anything existent.

It's far easier to get a CRT with its deflection yoke (the copper coil and connector around the neck) from an existing, compatible compact Mac than, say, buying a 9" monochrome CRT from the era and swapping over the deflection yoke (which I've recently been getting into) and making all of the adjustments necessary. Not to say you won't have to get your hands dirty with one option over the other—you'll need to swap a few things, in the event that your screen is bad. I'd re-cap the analog board first, make some adjustments to the board trimmers before you go about getting a new CRT, however.

Following this guide, you'll see which compact models are compatible with one another. ***Unless you know for sure you're buying an early-production version, I'd avoid the Classic model, as they switched connectors partway through their run.





I got very lucky with the Classic I bought last year (I had originally intended to fix what I thought was a simple RAM SIMM issue, but ended up being more trouble than it was worth to me, so it became a parts machine.

 

[superjer2000]

Or its a weak CRT. it can happen. 

Yup - 

One of my SE/30s had this exact issue.  The screen was really dim.  I recapped the analog board with no change in brightness so I swapped out the tube from a Classic with a nice bright screen and that was that.  Of course now the Classic has a dim screen …  Maybe that's a candidate for a new different color (green, amber?) CRT if there is some consensus of viable options for CRT replacement in that other thread.

 

[jessenator]

if there is some consensus of viable options for CRT replacement in that other thread.

I don't know to which thread you refer, but from from the more knowledgeable, almost all 9" CRTs of that era used the same pin connector. It's more of a matter of having a spare deflection yoke and (possibly) extended neck board connector. After that it's just a matter of sticking your hand near a high voltage (tens of thousands) device :lol: But in all seriousness, it was daunting to begin with, but if you follow basic HV safety (and possibly print yourself a plastic set of channel lock pliers) you're well out of harm's way. As far as mechanical adaptation, it's certainly doable, but takes a bit of brain bending.

@VMSZealot it very well may be that you need a new tube, but it's probably wise to tend to the AB anyway, if only to reflow any bad solder joints pointed out in JDW's video. My SE/30's AB-to-yoke plug was pretty bad, so I'm glad I did it. I'm also none the worse for a re-capped board. It's also cheaper than a CRT, unless you're crazy and buy one of questionable operation *sheepish shrug*

 

[PotatoFi]

Adrian's Digital Basement recently did a video on rejuvenating dim Macintosh CRT's. Might be worth holding onto the dim one and not tossing it.

 

[techknight]

ive used rejuvenation many times in the past with TVs and other things, it doesnt last. Its a temporary thing, because what it does is blow off the oxides of the cathode material on the CRT itself, but with it you lose a bit more emissive cathode material. Eventually it will fade in short order and youll lose the CRT entirely. 

Its good enough to boost a little life out of it, but once it reaches that point its basically the end of the road for that CRT. 

 

[mitchW]

Just a quick question,

I have an SE/30 that I think has a tube on its weak side.

Can anyone confirm that?

The focus is not as sharp, also I can make edges quite sharp, but the center will be bit soft and vice versa.

Also I noticed that the top and bottom corners are bowed a bit in, hard to describe, but it looks like a geometry problem, however if I max the brightness, the thing worsens, also if I drop the brightness down a lot, it looks almost perfect.

Should I look for a problem on analog board? I highly doubt it however, as it was doing the exact same thing 12 years ago when I got it, and since then it should worsen if this was a dying capacitor issue IMHO.