CRT compatibility

[iantm]

I want to pick up at least one spare CRT in case something ever goes amiss, now that I've been reminded that CRTs in general are no longer being produced. I kinda knew that, but just didn't think about it, and what I don't want is to someday have to replace it and find out — there just aren't any.

But I'm not sure what to get on eBay. I know what the CRTs and connectors look like from all the SEs and SE/30s I've pulled, but there are some that I'm finding that hav ea very different connector.

This was pulled from a Plus. I have several donor tube connectors like the one below. Is it safe to assume any of these CRTs will work, provided I have a spare tub connection? I'm assuming that the one in the photo above will not work, because it's designed for a Plus.

 

[Garrett]

The CRTs themselves are all interchangeable from the 128k through the Classic II. What is not interchangeable are the yokes and neck boards. If you have a dead tube, you'll have to swap over the neck board and yoke assembly from the destination machine.

There's a caveat though - if you move yokes between tubes, the geometry will likely be off. The magnets spaced around the yoke are configured at the factory for a specific tube, and if you swap tubes, that image alignment will have to be done again. I've done it, but it's super time consuming and you may drive yourself crazy in the process.

To avoid having to readjust the yoke magnets, I did try to re-pin the yoke connector to use a tube from a Mac Classic in an SE, and found that the yokes were still not compatible despite putting the right connector on the end. Must be a different amount of windings. I hope this knowledge is useful in your search for a spare CRT!

 

[iantm]

I figured it would be something of that sort… not immediately transplantable. I ended up finding one the same yoke connector (not the smaller white connected above) so I'm confident it'll work out of the box.

Either way, good to confirm the complexity of it.

 

[iantm]

The CRTs themselves are all interchangeable from the 128k through the Classic II. What is not interchangeable are the yokes and neck boards. If you have a dead tube, you'll have to swap over the neck board and yoke assembly from the destination machine.

That sounds like too much risk. I don't want to have to pull the yoke coil off and try and retune it.

If it's only a matter of geometry, though, I think I can deal with it — the concern is whether it's electrically safe or not.

The CRT seems to be a mechanical match — I can use the spare yoke pin connectors I have, it turns on, it runs really, really. bright. I had to use the analog board to turn the brightness way down.

Is that an issue? Will it run the risk of abusing the analog board?

If that's the case, I might be willing to sell or swap the CRT for one known to work in a SE with minimal burn in.

But I'm hoping someone might convince me that it's ok/safe to use this CRT as is, though I'm gathering that it might not be wise.

 

[S. Pupp]

The magnets spaced around the yoke are configured at the factory for a specific tube, and if you swap tubes, that image alignment will have to be done again. I've done it, but it's super time consuming and you may drive yourself crazy in the process.

I once put my SE/30 project on hold for a full decade after spending a day fiddling with the magnets. I valued my sanity, and was at risk of losing it.

 

[iantm]

Yeah I wouldn’t want to commit to that either… but is it actually unsafe/unwise to just swap the yoke connector and use it? I’m concerned it will cause lasting damage.
When I plugged it in, it worked. It was bright and a little distorted but otherwise usable.
But then I got wind that it’s too much for the way the se analog boards are set up and might damage it. Hoping someone can confirm or deny this. Either way until I know I’m not using it.

 

[iantm]

Follow up: Removed the plastic (carefully) and the 30Video card fit just fine. Realizing after much input that it's safe to say all these CRTs are within the range of Apple's specs and all I had to do was tune the analog board a little. I'm sure it helped that my Analog boards were freshly capped. Either way, it turned out to be a very nice spare CRT, if a bit pricey.

 

[Nitram78]

@iantm, slightly OT, but where does this nice FloppyEmu case come from ?

 

[iantm]

@iantm, slightly OT, but where does this nice FloppyEmu case come from ?

It's a derivative of this case by CYUL on printables. I cut out a hole for an Apple Macintosh badge reproduction by MacEffects, and printed the buttons with Polar Filament: Retro Platinum (thanks @jcm-1 !), Light Blue, and Candy Red. I haven't gotten light pipes that work yet.