Converting from CRT to LCD and updating video output in Compact Macs

[retr01]

Hello!


I tried to find if there was a thread already here on Tinker Different about this but have not. Some people did talk about it elsewhere, though. So, here I go.

I understand that many like to keep the Compact Macs the way it was back in the day. On the other hand, I want to give them modern enhancements so that they can continue to be useful today and in the future. One of the things I wondered about is converting from CRT to LCD in compact Macs. I understand that it is relatively easy to do.

Yet, there is one riddle I have not fully solved. Will removing the flyback transformer, anode cable, video board, and CRT cause the logic board (LB) to panic based on the ROM and the overall design? There are ways to continue the video output to a small LCD internally. Yet, I wonder, will the LB still panic because there is no communication with the video board that is gone along with the CRT?

Conversely, wouldn't that be unsafe if the flyback transformer and video board were left there after the CRT was gone?

I believe there is a way to remove the CRT, flyback transformer, and video board, and the compact Mac can continue to function through an alternative video out set up. For example, certain wiring modifications adapt the TTF video output to the RGB2HDMI adapter. Please note that this is not the same as the PDS color video card.

What are your thoughts about this? Please let me know. I would love to hear from many of the awesome tinkers here!

 

[AndyDiags]

On the newer compacts Macs where the analog board is separate from the power supply this may be more feasible, but I don’t see how replacing a CRT with and LCD would be an enhancement that makes it more useful today.

This would be the equivalent of taking apart an old working CRT tv, pulling out the tube inside, and replacing the tube with an LCD screen.

 

[retr01]

On the newer compacts Macs where the analog board is separate from the power supply this may be more feasible, but I don’t see how replacing a CRT with and LCD would be an enhancement that makes it more useful today.

LCD screens are sharper and more precise than any CRT. An LCD with the acrylic sheet preserves the CRT curvate shape from Retro Apple Mods. The guy is willing to make more upon request.

The additional benefits include eliminating high voltage, creating green energy savers, and increasing the hardiness and toughness. The coming modern parts would be more compatible. There would be more room in the case for other expansion options with modern parts. With the CRT, compact Macs are somewhat fragile, consume energy more than necessary, and are not green energy compliant.

Back in the day, people had those compact Mac bags. I have one. I plan to carry it and use it elsewhere like back in the day. With the LCD, the Mac would be lighter.

Another thing, could 12v power be delivered to the LCD from a point on the AB? I messaged Retro Apple Mods to find out more about power requirements. I have been informed a standard 12v power supply with center positive will work. Running from the HDD power out at P5 or the fan wiring from P3 on the AB will supply 12v to the LCD.

This would be the equivalent of taking apart an old working CRT tv, pulling out the tube inside, and replacing the tube with an LCD screen.

Well, yes. However, the high voltage (HV) transformer and HV flyback must be removed for safety reasons. The question is, once those two parts are removed from the Macintosh SE analog board (AB) in the SE or SE/30, will the Mac still function fine with the AB acting as a low voltage (LV) power router to the logic board (LB), HDD, and fan from the LV Sony CR44 or Astec PSU while the video is outputting as TTL to RGB2HDMI to the replacement LCD screen in 1-bit B/W?

​

Reviewing the Bomarc schematics for this AB, I wonder if removing those HV components may interrupt the necessary HV power delivery greater than 12v for something other than the red CRT andode? I can see that 13kv delivers to the CRT from the flyback, which is HV to be removed as it is not needed for the LCD.

I guess one thing I can do is to hunt down a Macintosh SE AB and do the experiment if no one ever tried that? I am sure some already have, and I am waiting to see if anyone has or knows someone who did.

Do you know @AndyDiags? What about @JDW? @Zane Kaminski? @Kai Robinson? Anyone else?

 

[Trash80toG4]

Are you driving the LCD from the OEM mobo, an expansion card sans CRT, putting in a replacement mobo and high res LCD?

 

[retr01]

Are you driving the LCD from the OEM mobo, an expansion card sans CRT, putting in a replacement mobo and high res LCD?

Hi @Trash80toG4,

No card. TTL output 1-bit B/W via header on a simple adapter between the LB and AB. From there will run from RGB DB9 to the LCD through RGB2HDMI.

Without the CRT, no point for HV, but keep the AB to route power to LB and other parts as usual from PSU as it is easier than modifying the PSU to add more wires and then removing the AB.

 

[retr01]

So, that is why I am trying to find answers, as I want to make sure that the AB and LB will still function without those two HV parts.

 

[Kai Robinson]

Well, i can power the SE and SE/30 logic boards just fine off a Meanwell RT-65B Power Supply, without even using the Analogue board. If you were using an LCD screen, that PSU would provide more than enough power to run the screen, too. The logic board doesn't care about the analogue board, there's no 'feedback' to it - just the video output that goes to the analogue board - you can intercept the signal and do whatever you wish to it.

@techav has a SE video adapter that plugs into the PDS slot, that can output to VGA. The idea, iirc, was to take the 512x342 display, pixel double it to 1024x684 and then pad the image by 84 pixels to display it on a standard 1024x768 panel. That way, all you need is a VGA LCD panel that can fit in the space left behind by the CRT, and voila.

 

[retr01]

Well, i can power the SE and SE/30 logic boards just fine off a Meanwell RT-65B Power Supply, without even using the Analogue board. If you were using an LCD screen, that PSU would provide more than enough power to run the screen, too.

That is a great idea, @Kai Robinson! I noticed in another thread that @SteveHere mentioned that the Meanwell RT-65B could fit inside the Sony CR44 PSU housing? Then again, how is the PSU mounted in the SE or SE/30 case without the AB? Perhaps a 3D printed board with the same holes to line up the chassis on the side and attach the PSU lined up correctly? @Kai Robinson, I saw you post a picture of your Meanwell PSU with a power switch that lights up? Were you able to place that flushed well in your SE or SE/30 case?

The logic board doesn't care about the analogue board, there's no 'feedback' to it - just the video output that goes to the analogue board - you can intercept the signal and do whatever you wish to it.

So, I could remove the flyback and transformer and continue to use the AB with PSU without any issues with the LCD replacing the CRT?

@techav has a SE video adapter that plugs into the PDS slot, that can output to VGA. The idea, iirc, was to take the 512x342 display, pixel double it to 1024x684 and then pad the image by 84 pixels to display it on a standard 1024x768 panel. That way, all you need is a VGA LCD panel that can fit in the space left behind by the CRT, and voila.

@techav, can you please explain more about the PDS adapter, which takes TTL of 512x342 and outputs to 1024x684 on an LCD? What is the name and model of that adapter? If you look at this thread, I got a different adapter and am planning to use it to project to a big LCD or a monitor via RGB2HDMI. I am curious how that would compare to the adapter that you are using.

 

[Kai Robinson]

Yeah i'd use a sheet of acetate or something to mount it - no need to 3D Print - just drill the holes - quicker, cheaper, easier. I never mounted mine in the case, it's role was as an external test bed PSU - but it worked just fine.

With an LCD no analogue board is ever needed, just tear it out and make a mount for a replacement PSU.

 

[retr01]

Okay! Thank you, @Kai Robinson. That means I need to look into placing the Meanwell RT-65B PSU in the Sony CR44 PSU housing with the necessary wirings to be ready for the swap.

 

[-SE40-]

Hi, just jumping in…..

When the CRT is gone, there is sooooo much extra space to play with

My guess for placing the meanwell inside the original sony CR44 PSU is to keep it looking like original.
As the CRT is gone, your SE30 isnt original anymore…
so why put it inside the CR44 (and make it bigger)

If I where in your situation, and the CRT+ logic board is still working fine, i would take it out, keep it original and store it somewhere safe. That is for what ever reason you gonna change your mind in the future, you can make your SE30 original again.

Or (like me) leave your mac original and get yourself a defect Mac to experiment with.
Ive been toying with the Macintoshes enclosures for some time now…
See the pinterest link in my bio, or check my current project.
(https://tinkerdifferent.com/threads/a-takky-mac.1363/)

Njoy!

Greetings, Chris.

 

[JDW]

@retr01
How are the reflections when using that acrylic sheet versus the antireflective stock CRT? Although an LCD will be more crisp and pixel perfect than a CRT, I'm curious if the reflections diminish the overall look of the screen. No doubt it's more reflective than even some older iMacs due to the utter absence of an anti-reflective coating on it.

 

[retr01]

Hi, just jumping in…..

Hello, @-SE40-!

When the CRT is gone, there is sooooo much extra space to play with
My guess for placing the meanwell inside the original sony CR44 PSU is to keep it looking like original.
As the CRT is gone, your SE30 isnt original anymore…
so why put it inside the CR44 (and make it bigger)

Yes, that is true.

If I where in your situation, and the CRT+ logic board is still working fine, i would take it out, keep it original and store it somewhere safe. That is for what ever reason you gonna change your mind in the future, you can make your SE30 original again.

I have thought of that, yep.

Or (like me) leave your mac original and get yourself a defect Mac to experiment with.
Ive been toying with the Macintoshes enclosures for some time now…
See the pinterest link in my bio, or check my current project.
(https://tinkerdifferent.com/threads/a-takky-mac.1363/)

Yes, I am planning to find a defect SE/30. The downside is defect SE/30s average about $150 to $200. Yeah, I know. Go figure.

Cool! I will check it out for sure! Thank you.

 

[retr01]

@retr01
How are the reflections when using that acrylic sheet versus the antireflective stock CRT? Although an LCD will be more crisp and pixel perfect than a CRT, I'm curious if the reflections diminish the overall look of the screen. No doubt it's more reflective than even some older iMacs due to the utter absence of an anti-reflective coating on it.

Hi @JDW! That is a great point. I have not yet ordered the LCD screen with an acrylic sheet as I am working on restoring my SE/30 to its original condition and would instead find a defunct SE/30 for the fun modifications. The acrylic sheet is reflective like my daily driver MBA M1. I have experienced both, and no doubt almost all of us have. Yet, if I wanted the modified SE/30 to be anti-reflective, I could place a 3M Anti-Glare Filter on the acrylic sheet. Using a tape measure, the correct size can be trimmed before installation.

 

[-SE40-]

Looking forward to see where your project is going!

 

[Trash80toG4]

If you're doing an SE/30 board, definitely be on the lookout for a VidCard to run the LCD at a higher resolution. If you pull the Video ROM the SE/30 will have no idea onboard video exists. Video ROM is the functional equivalent of the VidCard's Declaration ROM and polled by Slot Manager at startup. If the Video ROM is not there, voila, no onboard video subsystem, the LCD becomes the startup screen.

 

[Trash80toG4]

@retr01
How are the reflections when using that acrylic sheet versus the antireflective stock CRT? Although an LCD will be more crisp and pixel perfect than a CRT, I'm curious if the reflections diminish the overall look of the screen. No doubt it's more reflective than even some older iMacs due to the utter absence of an anti-reflective coating on it.

I'd not worry about the reflections, Laptops and Displays have had high gloss LCD finishes that it would look perfectly fine today, if not period correct.

 

[retr01]

If you're doing an SE/30 board, definitely be on the lookout for a VidCard to run the LCD at a higher resolution.

Right.

If you pull the Video ROM the SE/30 will have no idea onboard video exists. Video ROM is the functional equivalent of the VidCard's Declaration ROM and polled by Slot Manager at startup. If the Video ROM is not there, voila, no onboard video subsystem, the LCD becomes the startup screen.

Wow, @Trash80toG4, thank you for sharing.

I'm looking for the Video ROM on the SE/30 LB, and I think it's that one here.

​

Reviewing pages 234 and 244 in Apple's Guide to the Macintosh Family Hardware, I see the powerup and startup process clearly outlined. Yet, where is the step-by-step process that includes polling by the slot manager at startup after the reset handler begins the startup procedure? Aha, on pages V-354 and V-355 in Apple's Inside Macintosh Volume V, I found it!

The second sentence of the last paragraph on page V-354 reads:

"If sdSlot returns 0, there is no default video device, and the first available video device will be chosen."​

​

Going back to pages V-348 and V-349 regarding the initialization process of the Start Manager, the last bullet point reads:

"On the Macintosh II [the SE/30 is part of the Macintosh II Family], the Start Manager looks for a video card to use as the main video display...if the specified card isn't found, it looks for the first available video sResource."​

Yep! As long the PDS video card has video ROM that has a recognized and acceptable parameter of the declaration ROM as a video sResource, that will become the default video card in the absence of the onboard video ROM chip.

So, the question remains, which video card is acceptable for this Tinker differently hack? What about some video cards for the IIsi? Here is a list of video cards that I know so far for the SE/30:

Lapis (FOCUS Enhancements)​

ProColor 8​

ColorServer PDS/30 / PDS30-17 / PDS30-21​

ProColorServer 24 PDS/30​

SE/30-DPD​

Color16 for SE/30​

​

Micron Technology​

MacroColor 30​

Xceed 306​

​

Radius​

Radius Pivot Card SE/30​

​

RasterOps​

ColorBoard 108+SE/30​

ColorBoard 264 for SE/30​

ColorBoard 708+SE/30​

ColorVue GS/30​

​

SuperMac​

SuperMac ColorCard SE/30​

​

Interware​

Vimage CAD SE/30​

Vimage 8 SE/30​

Vimage SE/30​

​

E-Machines​

TX SE30/8​

T19 SE30/8​

​

Formac​

ProNitron 80.SE/4​

ProGraph SE/3​

 

[Trash80toG4]

Thanks for running down and listing specific notations in the documentation. My observation was based on my ingrained Neanderthaler approach to hacking. Pull the offending Video ROM and test results with and without VidCard. Determined what you just quoted from general understanding of the process from references in the DCaD series, etc.

Some folks have said that the onboard video's registers might be problematic, but that makes no sense to me. The system has no reason to load anything anywhere without the drivers present in the Video ROM.

Not sure about resolutions available on 030 PDS VidCards. We need to build a database at some point, most VidCards aren't even listed on the always questionable LEM pages. Here's the Gamba table:

Vintage Apple - Gamba - Video: Nubus card-Monitor Matrix

I'd start my research backward from the Monitor/VidCard combos available. IIRC, some supported 640x480@60Hz due to the display choice?

If you're in touch with the etsy guy, ask him if the display controller will default to full screen 640x480 input on the 1024x768 panel. The controller is almost certainly not MultiSync, but may support that lower res VGA input standard?

Where did you come up with your 030 PDS VidCard listing? Nice work, BTW.

 

[retr01]

Thanks for running down and listing specific notations in the documentation. My observation was based on my ingrained Neanderthaler approach to hacking. Pull the offending Video ROM and test results with and without VidCard. Determined what you just quoted from general understanding of the process from references in the DCaD series, etc.

I do the same thing as well. I troubleshoot by finding whatever barrier, there is towards the desired goal. I have worked as a Technical Support specialist for about ten years. Nowadays, sometimes I forget those skills.

Some folks have said that the onboard video's registers might be problematic, but that makes no sense to me. The system has no reason to load anything anywhere without the drivers present in the Video ROM.

Not sure about resolutions available on 030 PDS VidCards. We need to build a database at some point, most VidCards aren't even listed on the always questionable LEM pages. Here's the Gamba table:

Vintage Apple - Gamba - Video: Nubus card-Monitor Matrix

I'd start my research backward from the Monitor/VidCard combos available. IIRC, some supported 640x480@60Hz due to the display choice?

@Trash80toG4, Tinker Different would be an excellent place under Resources. Alternatively, I will be happy to host databases, tables, specs, schematics, etc that are newly created and clear on my website. I have good web development skills and I want help doing that. Many sites have not been updated or maintained for a long time. IMHO, those sites are sometimes difficult to navigate and the information is unclear, which can be annoying.

Information for tinkering should be clear and understood in plain language. Excessive use of lingo and being too technical should be avoided.

If you're in touch with the etsy guy, ask him if the display will default to a full screen 640x480 feed. The controller is almost certainly not MultiSync, but may support that lower res VGA input?

Good idea. I will ask. (Update: I have sent a message to the Esty seller, Retro Apple Mods.)

Where did you come up with your 030 PDS VidCard listing?

Some old sites have lists of 030 PDS video cards, such as Gamba, LowEndMac, and SE/30 Forever. I have seen some cards pop up on eBay and other marketplace sites. I populated that list from SE/30 Forever as an example. I am sure more 030 PDS video cards will work, too.