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Larger CRTs on Early Compacts
- Thread starter raoulduke
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[As I mentioned to you in the other post, the Compaq Plus did not work, and is entirely intact albeit disembodied [so the "another" would not apply].]
And unrelated, except to the topic, I'm pretty sure this specific thought will work. http://www.classic-computers.org.nz/blog/images/2012-07-03-inside-model1-monitor.jpg(although this is a Model I)
And unrelated, except to the topic, I'm pretty sure this specific thought will work. http://www.classic-computers.org.nz/blog/images/2012-07-03-inside-model1-monitor.jpg(although this is a Model I)
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Anything is possible in theory, if you're willing to throw enough time, money and circuitry at it. But I'm going to make a wild guess at "not easily".
The recipe for the UglyMac and other clues about the place suggest that the video output from a b&w compact is roughly the same as PC-world EGA in terms of timing. One of those, you would want to check for yourself. If you find a nice big monitor that matches timing-wise, you miiiight just get away with a little circuitry in between to make the sync and signal polarity match what the monitor is expecting. But plug and play? Nope.
The recipe for the UglyMac and other clues about the place suggest that the video output from a b&w compact is roughly the same as PC-world EGA in terms of timing. One of those, you would want to check for yourself. If you find a nice big monitor that matches timing-wise, you miiiight just get away with a little circuitry in between to make the sync and signal polarity match what the monitor is expecting. But plug and play? Nope.
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If the pins on the CRT itself are identical (I think this is the case with the compact, Lisa, and Apple 12" monochrome CRTs), couldn't you use the compact's own video circuitry to drive the larger tube? The tube doesn't care about timings and signal polarities, does it? I am literally asking, not challenging any statements anyone has made.
raoulduke: Do with your own toys whatever you want. You run the risk of becoming the neighbor kid from Toy Story if you let it get out of hand.
raoulduke: Do with your own toys whatever you want. You run the risk of becoming the neighbor kid from Toy Story if you let it get out of hand.
the pinouts of most Black and White tubes are the same.
But there are two catches here. G1/G2 voltage requirements may be different, so it may not be brought into focus.
Also the High Voltage requirement of a larger CRT will almost certainly be required. So you will have raster blooming, or overall dimness.
Smaller CRTs need anywhere from 8K to 10K volts. Larger CRTs need 12 to 14K.
Color CRTs need around 20 to 26K volts, in order to force the beam through the aperture grid/Shadow mask.
But there are two catches here. G1/G2 voltage requirements may be different, so it may not be brought into focus.
Also the High Voltage requirement of a larger CRT will almost certainly be required. So you will have raster blooming, or overall dimness.
Smaller CRTs need anywhere from 8K to 10K volts. Larger CRTs need 12 to 14K.
Color CRTs need around 20 to 26K volts, in order to force the beam through the aperture grid/Shadow mask.
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Well there's increased voltages and a new sweep time which means that even if you get a stable image the voltage will be too low for you to properly see it. You can't just hang a larger tube in a compact mac and expect it to work. Most of the mods to run a larger screen basically took the video signal to the analog board and sent it somewhere else in a modified format, often enough it was composite. You will not get high resolutions if that is what you are after unless you use entirely new video circuitry.
When I replaced the broken Samsung CRT with the Clinton green monochrome from my Compaq Plus, which didn't work [Gorgotron...], I replaced the neck (coil) with the original SE/30 neck. Just using the SE/30 graphics board dealt with any of the pin-out differences and (along with replacing the anode) the flyback transformer/bleeder resistor, since the design on the Compaq was different and involved two anode-leads. I've only turned that config on twice though to avoid burn-in from the high resistance phosphor [...Gorgotron... [yes... I'm familiar with the added accuracy of scrolling up...]].
In this case, I've had all these machines since the late-90s. They are entirely original in their components because I have mostly not used them. My goal was not specifically preservation, but that has been the effect. And on that point, of course, because of the imperative for preserving antiques, I assume all your machines are entirely original - as are the few I consider to be in my collection? You haven't recapped them, choosing functionality over form? Because if you have, it seems that the source of your vitriol is ignorance and not principle.
Why is it ignorance? Per my words above about having these machines for a decade and a half and not using them: I was thinking about entirely removing the innards from one of the TRS-80 all-in-one machines, including the CRT, and replacing it all with a Mac logic board and new - albeit larger - CRT as a sort of ad hoc, ironic, Lisa look-alike. So I wasn't planning on affecting any of the internals [exactly like with the Compaq, although as I said I have twice - for a cumulative 5 minutes - used the CRT with an SE board]. What's with the kid in Toy Story... was he creative? [lol]
In any event, I appreciate the info about voltages. Were I to pursue this, when I have time, that's what I'd look into. My preface about the neck/coil and the controller board speak to the fact that there are very unlikely to be physical [literally in this case visible] incompatibilities - since as someone mentioned, the CRTs themselves are probably visibly uniform in their interfaces. The issue would be whether that uniformity belies differences in voltage or polarity - or some other standard [i'm honestly curious how the graphics board will control for size and resolution, since the onboard (/30 analog board) controls are only vert/horiz but not size]. Were I to do this, I'd likely try to find an expendible logic board and CRT. I don't know if I have any old non-computer CRTs anymore.
In this case, I've had all these machines since the late-90s. They are entirely original in their components because I have mostly not used them. My goal was not specifically preservation, but that has been the effect. And on that point, of course, because of the imperative for preserving antiques, I assume all your machines are entirely original - as are the few I consider to be in my collection? You haven't recapped them, choosing functionality over form? Because if you have, it seems that the source of your vitriol is ignorance and not principle.
Why is it ignorance? Per my words above about having these machines for a decade and a half and not using them: I was thinking about entirely removing the innards from one of the TRS-80 all-in-one machines, including the CRT, and replacing it all with a Mac logic board and new - albeit larger - CRT as a sort of ad hoc, ironic, Lisa look-alike. So I wasn't planning on affecting any of the internals [exactly like with the Compaq, although as I said I have twice - for a cumulative 5 minutes - used the CRT with an SE board]. What's with the kid in Toy Story... was he creative? [lol]
In any event, I appreciate the info about voltages. Were I to pursue this, when I have time, that's what I'd look into. My preface about the neck/coil and the controller board speak to the fact that there are very unlikely to be physical [literally in this case visible] incompatibilities - since as someone mentioned, the CRTs themselves are probably visibly uniform in their interfaces. The issue would be whether that uniformity belies differences in voltage or polarity - or some other standard [i'm honestly curious how the graphics board will control for size and resolution, since the onboard (/30 analog board) controls are only vert/horiz but not size]. Were I to do this, I'd likely try to find an expendible logic board and CRT. I don't know if I have any old non-computer CRTs anymore.
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And anything of that age, thats likely to happen.
Would be nice if you traced it down, and fixed her up!
Would be nice if you traced it down, and fixed her up!
That is probably beyond my abilities but there are some tells, maybe. The second time I powered it on the screen didn't come on until I flipped up the drive closing mechanism. The first time I think it didn't start until I pressed break on disk startup (procedure for booting from cassettes).
Otherwise it wobbles a bit (the screen image), which I think I've read about here regarding old Mac CRTs.
Otherwise it wobbles a bit (the screen image), which I think I've read about here regarding old Mac CRTs.
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Bad solder joints.
Oh, dear. Your rapier-sharp wit hath cut me to the quick. Good show, old man!
So... after a stream-of-consciousness rant in which you lay out a case for destroying an antique computer (on the basis that it's not "worth enough" financially for you to care about?) for a kicks and giggles case mod and accuse me (with no basis whatsoever) of being "ignorantly" against things like recapping or upgrading (IE, *not* destroying*) said antiques you suddenly turn around and say you're "not going near it with solder" (to *repair it*) yet are a "purist for keeping these machines alive"? Whatever dude.
Anyway. These things are your toys and if your chosen modus operandi is going to be to neglect them until they trivially break, at which point they become game for whatever mindless desecration crosses your mind, that's your business; I'm certainly not going to pay you a ransom to *not* gut your Model III. Frankly my only point is, I don't know, if you don't give a damn about TRS-80's maybe it might be nice to post a "for sale" ad on the Vintage Computer Forum or just slap them on eBay and let someone who does appreciate them have them. A III/4 without accessories generally only sells for $50-$150, which just about puts them in the "costs more to ship than they're worth" category, (also mostly true of items like a Mac Plus or most other Beige macs, so far as that goes) so sure, if "Money" is the only reason you can see not to destroy one then I'm sure that's not going to be enough to stop you. Just don't pretend you're somehow better than someone who does care *a little* about the intrinsic historical value of the old doorstops.
I misremembered your name and then - completely refuse[d] to - correct myself. [These have both been Aqua Teen Hunger Force references.]
Clearly the dichotomy you see is destroy/repair, whereas the dichotomy I was asserting was original/modified. I was asserting that modification is a form of destroying. It may also be seen as a form of repair. I suppose it depends whether you privilege the machine's original form [the 'antique' you're referring to] or its functionality. I guess I've been lucky enough mostly not to have to make that choice with my collection so far.
I don't trust myself not to destroy something if I go at it with solder. That was the source of my comment. But I did write that in a confusing way so it would have been impossible not to connect those thoughts [per your excerpt]. Re-soldering, by itself, pushes the boundary of what I'm referring to with modification. But I don't trust myself not to destroy something and there's no guarantee it is a component issue.
[My ransom comment, which I removed because it was petty [i'm not sure if that's what you were referring to], was both to highlight the limited impact of the value of these machines as well as the remote nature of your [spurious] comments. As I pointed out with the Compaq in another topic, and was frankly pretty offended you didn't follow up on after spuriously accusing me of destroying another 'antique' machine, was that a) the machine didn't work, and b ) I didn't destroy anything except for part of a sort of [inside-the-case] outer guard frame for the CRT, which has no specific effect on the outward appearance or functionality [of the non-working machine]. So when you made the same spurious accusation again, I thought it best to point out that I had again been speaking theoretically about removing the internals and using the case [a thought I think I had previously mentioned on that other topic regarding the Compaq case]. That generated my thought about what would happen with larger CRTs in a compact Mac [and that, sort of meshed with the first thought, formed the basis for this thread]. That generated your accusation that I was destroying an antique.
I understand the chain of your inferences. They are not illogical. However, it would seem to me you could move toward clarification before - twice now - spuriously accusing me of attempting to destroy my own personal property - property that I've preserved pretty well for 15 years. I suppose I can understand your offense in this context. It has some logical basis. However, I don't think my right of reply here - however stream of consciousness - is inappropriate since I find the caprice and repetition of your remarks offensive. Just because we can do a thing, it does not necessarily follow that we must... do that thing. [These have both been Star Trek VI references.]]
Whatever dude.
Clearly the dichotomy you see is destroy/repair, whereas the dichotomy I was asserting was original/modified. I was asserting that modification is a form of destroying. It may also be seen as a form of repair. I suppose it depends whether you privilege the machine's original form [the 'antique' you're referring to] or its functionality. I guess I've been lucky enough mostly not to have to make that choice with my collection so far.
I don't trust myself not to destroy something if I go at it with solder. That was the source of my comment. But I did write that in a confusing way so it would have been impossible not to connect those thoughts [per your excerpt]. Re-soldering, by itself, pushes the boundary of what I'm referring to with modification. But I don't trust myself not to destroy something and there's no guarantee it is a component issue.
[My ransom comment, which I removed because it was petty [i'm not sure if that's what you were referring to], was both to highlight the limited impact of the value of these machines as well as the remote nature of your [spurious] comments. As I pointed out with the Compaq in another topic, and was frankly pretty offended you didn't follow up on after spuriously accusing me of destroying another 'antique' machine, was that a) the machine didn't work, and b ) I didn't destroy anything except for part of a sort of [inside-the-case] outer guard frame for the CRT, which has no specific effect on the outward appearance or functionality [of the non-working machine]. So when you made the same spurious accusation again, I thought it best to point out that I had again been speaking theoretically about removing the internals and using the case [a thought I think I had previously mentioned on that other topic regarding the Compaq case]. That generated my thought about what would happen with larger CRTs in a compact Mac [and that, sort of meshed with the first thought, formed the basis for this thread]. That generated your accusation that I was destroying an antique.
I understand the chain of your inferences. They are not illogical. However, it would seem to me you could move toward clarification before - twice now - spuriously accusing me of attempting to destroy my own personal property - property that I've preserved pretty well for 15 years. I suppose I can understand your offense in this context. It has some logical basis. However, I don't think my right of reply here - however stream of consciousness - is inappropriate since I find the caprice and repetition of your remarks offensive. Just because we can do a thing, it does not necessarily follow that we must... do that thing. [These have both been Star Trek VI references.]]
Whatever dude.
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No, see, it hurt me dearly because I do in fact look just like the Gorgatron. I think it's glandular.
Mmmmhmmm. Let's say you have an dog with a mangled leg. Your options are: #1: you take the animal to the vet and repair the leg with extensive surgical intervention involving screws, a steel rod, and a plastic hip joint, or #2: you kill the animal and have a taxidermist turn it into a Lassie-shaped beer tap. I think a reasonable person would say that you "repaired" the dog in the first case and "destroyed" it in the second. It may be a perfectly good beer tap but it is indisputably no longer a dog. I'm sure your argument would be in this case a Tandy with Mac guts in it would still be a "computer" but... no. All you're using of the original is the skin and that puts it squarely into "casemod" category. And while case mods can be clever and arguably acceptable if the donor system was really and truly scrap and beyond repair they tend not to go down that well in "vintage" circles.
But if something looks like it *might* plug into something else you're all for just rushing right on in there and see what happens? Honestly I'm glad you haven't been killed yet mucking around with CRTs. They'll happily do it for you if you don't treat them with respect.
I don't understand the attitude that you care for "preserving" these machines but the moment they blow a trivial component they're suddenly dead and prime for thoughtless gutting. The problem with your Model III's power supply is most likely aging capacitors, or possibly an iffy regulator; the power supplies Radio Shack used in them were sort of marginal for the two-disk configuration even when they were new and "screen shrinking" on disk access is a classic symptom. A few minutes replacing some components (after spending a few hours practicing on a scrap board from an old radio or something first) and it'll be as good or better than new... but no, you ain't gonna go there?
(In fact, if you want to learn how to repair digital electronics or otherwise learn computers at a low level you could do way worse than a Model III; computers like the III are among the last built entirely out of generic TTL logic with no proprietary ASICs, meaning it's almost completely repairable using standard electronics parts drawer bits. But, hey, maybe that's not where your interests lie. In which case, again, I'd caution you to stay away from parts like CRT power supplies that are full of analog black magic.)
Yes, it was. (And yes, I saw it.)
So, I'm sorry you took offense at the "another" part of my comment, I guess. Apparently that Compaq was totally asking for it and I stand corrected. Have fun or whatever.
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My Model III doesn't have a power supply problem. My Compaq does. Each progressive fuse blew every time I tried to turn the machine on [i have said this several times now]. If the old PC power supply I have in the basement doesn't match, then that's the end of the Compaq for the moment. So for the moment, that case is for a scrapped, and is in fact sitting in shell-form in my basement - but it has a 9" monitor slot.
I haven't touched anything else. It speaks exactly to your repetitive desire to just concoct and defame. How precisely does your constructed scenario [that I have destroyed... anything] speak either to reality or to this thread - which is about whether (or since we're beyond whether in theory) which larger CRTs could be compatible with the old compact Macs.
And keep in mind with regard to your dog analogy... these aren't living things. I'm perhaps not the most empathetic person, but I would heal that dog out of a desire to spare pain, not because I externally desire for them to function properly. TRS-80s don't feel pain. We don't know if they dream.
I don't care that you saw my comment about your remote and exogenous desire to forbid someone from doing something where it carried no cost and burden to you yourself. I removed it so it wouldn't continue to pollute this thread. Congrats on flouting that. If you have anything to add about the voltage/polarity issues of the CRT in the Models III or IV (though not directly relevant), or any other larger CRTs, it'd be much appreciated.
I haven't touched anything else. It speaks exactly to your repetitive desire to just concoct and defame. How precisely does your constructed scenario [that I have destroyed... anything] speak either to reality or to this thread - which is about whether (or since we're beyond whether in theory) which larger CRTs could be compatible with the old compact Macs.
And keep in mind with regard to your dog analogy... these aren't living things. I'm perhaps not the most empathetic person, but I would heal that dog out of a desire to spare pain, not because I externally desire for them to function properly. TRS-80s don't feel pain. We don't know if they dream.
I don't care that you saw my comment about your remote and exogenous desire to forbid someone from doing something where it carried no cost and burden to you yourself. I removed it so it wouldn't continue to pollute this thread. Congrats on flouting that. If you have anything to add about the voltage/polarity issues of the CRT in the Models III or IV (though not directly relevant), or any other larger CRTs, it'd be much appreciated.
You said the screen image is getting wobbly and it's not starting up reliably. That's very likely a power supply problem. (Possibly compounded by aging capacitors in on the monitors' analog board... but hey, I forgot, you have no interest in actually fixing any of these problems.)
Regardless... "Concoct and defame"? "remote and exogenous desire"?
Anyway, if you want something directly relevant beyond what a couple people who know what they're talking about have already contributed I'll attempt to clarify it a bit: Yes, the pinout on the back of the 12" CRT tube itself in a TRS-80 is *probably* the same as the 9" in the Compact Mac, but given what appears to be your tendency to conclude that if the plug fits it should "just work" that's frankly probably a dangerous thing to tell you. After all, you said this:
Do you think picture tubes are somehow "plug and play" and the board will just magically figure out what you've done and adjust everything automagically? Because, no, that's not how it works.
Anyway, if you were to thread the deflection yoke attached to the Mac's analog board onto a 12" CRT, which it may or may not fit depending on the model of each, and power it up you *may* get a dim and out-of-focus picture; as Technight noted the flyback transformer on the Mac's board quite likely won't completely make the larger CRT happy and/or might burn out trying. Further, the Mac's analog board itself is mostly "hard-wired" out of cheapness, IE, it's short on adjustment pots, so even if the analog board does have enough reserve in it to power the larger tube adequately you'll probably have to change out some resistors and other components to get a clear, centered, and properly sized picture. (And obviously the resulting picture will have the same 512x342 resolution that the 9" CRT shows because *that* is dictated by the digital circuitry on the motherboard, which likewise will have no idea whatsoever that you changed something.)
(As for using the "analog board" in the TRS-80 to drive the monitor by connecting it directly to a Mac motherboard that's also pretty much a non-starter for a novice. The TRS-80's monitor runs at NTSC frequencies, IE, about 15khz hsync, verses the 22khz the Mac runs at. It would need substantial work to sync at the faster rate and further the output from a Compact Mac motherboard isn't "normal" TTL video, it's a little "odd"; there was a thread about that a few months ago which boils down to even if you have a Multisync monitor that can sync at the Mac's frequencies you need a small amount of additional circuitry to turn the "raw" drive signals from the Mac into standard h/vsync signals.)
In short, this is an awfully ambitious project for someone who's afraid of soldering irons and only learned recently that the part of a CRT with the wires coming out of it wasn't something you could buy an ala carte replacement for when you let air into it.
Thank you very much for the info. These are details I would look into if I ever decided to go ahead with attempting to adapt a larger screen for a compact Mac. It's not clear to me why these topics can't be informative beyond themselves such that if anyone wanted this information in the future it couldn't be also helpful to them... Since I actually pointed out that the interface is identical, it seems that warning against simply attempting to plug-and-play [which, by the way, as I think techknight - also you I think - pointed out, probably would work - if not well] actually is quite helpful to me and anyone else with the socially irresponsible urge to, in the future, tinker with their personal property.
As for factual issues: The screen image sometimes does not come on. The CRT powers up reliably with the machine (the back of the CRT's neck lights up). That does not sound like a power supply issue to me, but I am not an expert. (I'm also pretty sure that wasn't what techknight was saying about the solder joints.)
As for impugning my usage of language... you have now several times made up details ["concoct"ed...] in an apparent attempt to derogate my character ["defame"]. (As with) Your initial insertion into this topic, because it only concerned an aforementioned concoction, was off-topic and therefore an inappropriate outsider-slight ["exogenous"] in relation to an object (my property) to which you have no direct connection ["remote"]. Excellent use of meme-pictures. But I think these words do mean what I thought they did when I used them. I'm also not clear on why I'd be using Word and hence its thesaurus to type in this web-form...
Honestly, I cannot fathom your self-righteousness. If this were an encounter in person, it would be foundationally and intractably awkward. In practical terms, at best your tone [or a similar tone] might stop unqualified people - as myself - either acquiring the requisite knowledge to maintain these machines or from asking questions before embarking on foolish endeavors that harm them.
I will not comment on this again. Have a nice evening.
As for factual issues: The screen image sometimes does not come on. The CRT powers up reliably with the machine (the back of the CRT's neck lights up). That does not sound like a power supply issue to me, but I am not an expert. (I'm also pretty sure that wasn't what techknight was saying about the solder joints.)
As for impugning my usage of language... you have now several times made up details ["concoct"ed...] in an apparent attempt to derogate my character ["defame"]. (As with) Your initial insertion into this topic, because it only concerned an aforementioned concoction, was off-topic and therefore an inappropriate outsider-slight ["exogenous"] in relation to an object (my property) to which you have no direct connection ["remote"]. Excellent use of meme-pictures. But I think these words do mean what I thought they did when I used them. I'm also not clear on why I'd be using Word and hence its thesaurus to type in this web-form...
Honestly, I cannot fathom your self-righteousness. If this were an encounter in person, it would be foundationally and intractably awkward. In practical terms, at best your tone [or a similar tone] might stop unqualified people - as myself - either acquiring the requisite knowledge to maintain these machines or from asking questions before embarking on foolish endeavors that harm them.
I will not comment on this again. Have a nice evening.
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