LisaList2

Quote from: berskyboy on September 28, 2026, 11:53:07 AM1. I also wanted to know how to ground the white wire

2. The small green and white wire seem to be grounds?

The white wire from the tube socket does go to the spade connector on the metal chassis as in your picture.

The two thin green and white wires go to the front panel safety interlock switch (near the bottom left corner of the CRT). Many people just disable the switch, so that may be why your wires are cut.

Quote from: sigma7 on September 28, 2026, 12:47:39 PMThe white wire from the tube socket does go to the spade connector on the metal chassis as in your picture.

so the white wire goes to the read circle?
https://www.dropbox.com/scl/fi/lgmzu07e6eve7dusb7v0t/White-Wire-goes-to-Red-Circle.jpeg?rlkey=0wxa7j8uncfm485z00tj1p9ht&st=t4yvxw57&dl=0

Also, do I need to worry about this? (I asked AI about the picture)

⚠️ Crucial Step: Where is the CRT Aquadag Ground Strap?
Because that white wire goes to the neck socket, you must verify the main CRT static grounding strap is still present.
- Look for a bare, uninsulated braided metal wire or a thin tension spring stretched tightly across the black matte coating (aquadag) on the wide, curved part of the glass funnel.
- This braided strap must connect to a grounding point on one of the four metal corner mounting ears of the CRT frame.

Double-check that the bare metal grounding strap is contacting the black glass coating before you reinstall the main plastic outer housing.

CRT televisions and monitors can cause serious injury or death, even when unplugged for days, weeks, or months. Read and follow all precautions before opening any CRT device.

LETHAL HIGH VOLTAGE

The anode (high-voltage) circuit can hold 20,000-30,000+ volts on the tube's second anode, the suction-cup connector on the glass.
Capacitors, including the tube itself, can retain a dangerous charge long after power is removed.
Flyback transformers and the associated circuitry can also deliver painful or dangerous shocks.

IMPLOSION HAZARD

The glass envelope is under vacuum and can implode violently if cracked, scratched, or struck.
Flying glass can cause severe lacerations and eye injuries.
Never carry a tube by its neck. Never apply pressure to the neck or the neck board.
Wear safety glasses or a face shield at all times.

BEFORE YOU BEGIN

Unplug the device from mains power.
Work only if you are trained or experienced with high-voltage electronics. If you are not, do not open the case.
Never work alone. Have someone nearby who can call for help and knows CPR.
Keep one hand in your pocket or behind your back when probing live circuits, to avoid a path across your chest and heart.
Remove jewelry and metal accessories.
Work on a dry, non-conductive surface. Keep liquids away from the work area.

DISCHARGING

Discharge the anode only with a properly insulated, high-voltage discharge tool and a known-good ground connection, following the correct procedure for your specific device.
Never use a bare screwdriver or improvised tool. This can damage components and injure you.
Do not assume the tube is discharged. Verify with an appropriate high-voltage probe.
Recharging can occur after discharge (dielectric absorption), so re-check before touching.

Quote from: TorZidan on September 28, 2026, 02:24:38 PMCRT televisions and monitors can cause serious injury or death, even when unplugged for days, weeks, or months. Read and follow all precautions before opening any CRT device.

hi TorZidan, yup it came unplugged and the CRT was even upside down.  I'm still working bench testing the PSU.  So no power as of yet.  And could have been for a decade or so , but yes I made a screwdriver with an alligator clip and have discharged few vintage CRTs (NeXT Monitor, Mac SE). 

My question was regarding what AI said, and I'm wondering if I'm missing any parts.

https://youtube.com/shorts/K4iUFtFl23A

Quote from: berskyboy on September 28, 2026, 04:05:19 PMI made a screwdriver with an alligator clip and have discharged few vintage CRTs (NeXT Monitor, Mac SE). 

For the benefit of others, that would be a "sufficiently insulated" screwdriver, as a few KV will go through the otherwise insulating handle of many screwdrivers. This kind of non-obvious detail is why the warning specifies "Work only if you are trained or experienced with high-voltage electronics." Working around the CRT is dangerous: proceed at your own risk!

Also, the alligator clip is typically wired through a high value resistor so the current surge is limited.

Note that the high voltage of the CRT stinger will damage/destroy a DMM unless a working high voltage probe is used properly. According to the video board schematic, the Lisa CRT HV is 13KV (and may be higher if there is a fault in the circuitry). DMMs are typically limited to 1KV, some much less.

Quotethe CRT was even upside down.

An upside down CRT might be intended as a warning sign. You've found quite a project!

QuoteMy question was regarding what AI said

It is good you asked. It looks like AI has led you astray a couple of times already, so we should all take its responses as "concepts to investigate" rather than "directions to follow" as worded.

The black coating/paint on the CRT should have a low resistance to the chassis. This connection is made (on some Lisa CRTs at least) via a flat copper spring loop at one side of the CRT. (Different from what AI said it would be)

If the spring isn't there, and you don't have a low resistance from the chassis to the black conductive dag coating, then indeed some other connection is needed.

Quoteand I'm wondering if I'm missing any parts

In your video, I see a Widget hard drive (above the floppy drive), which if still working, you probably don't want to use since a modern emulator will give better performance, be more convenient, and preserve what life is left (if any) in the Widget.

The Widget does not have a power or data cable connected. What are the cables in that area that are not connected?

Given the other oddities, I wonder if you have a full wiring harness... check if there is a card edge connector for the PSU to plug into, another for the motherboard to plug into, and another for the video card to plug into. There should also be a connector plugged into the flyback transformer, the other ends of the thin green and white wires, and wires going to the speaker behind the front panel safety interlock switch. And finally, another (non-ribbon cable) connector in the drive cage area (there are two different types, depending on the type of wiring harness).

You may/probably need to clean and re-lubricate the 400K Sony drive if you wish to use it.

Quote from: sigma7 on September 28, 2026, 04:57:24 PM

Quote from: berskyboy on September 28, 2026, 04:05:19 PMI made a screwdriver with an alligator clip and have discharged few vintage CRTs (NeXT Monitor, Mac SE). 

It is good you asked. It looks like AI has led you astray a couple of times already, so we should all take its responses as "concepts to investigate" rather than "directions to follow" as worded.

The black coating/paint on the CRT should have a low resistance to the chassis. This connection is made (on some CRTs at least) via a copper wide spring loop at one side of the CRT. (Different from what AI said it would be)

If the spring isn't there, and you don't have a low resistance from the chassis to the dag coating, then indeed some other connection is needed.

So I'm not 100% certain what I'm looking for here, here's another look at the CRT

https://www.dropbox.com/scl/fi/e73juylm4yrwcdzws1lj6/Lisa-CRT.HEIC?rlkey=2nnsz4katm1txogbylds112kz&st=1lzh311w&dl=0

And I did created a 60 pin cable after watching Adrian's YouTube Video.

https://www.dropbox.com/scl/fi/fss0cuwubwnschhmr5564/Recreated-Ribbon.HEIC?rlkey=f5fkgyglxtyuvj0dl7lh3i2bn&st=ohtg7269&dl=0

Quote from: berskyboy on September 28, 2026, 05:36:42 PM

Quote from: sigma7 on September 28, 2026, 04:57:24 PMThe black coating/paint on the CRT should have a low resistance to the chassis. This connection is made (on some CRTs at least) via a copper wide spring loop at one side of the CRT. (Different from what AI said it would be)

So I'm not 100% certain what I'm looking for here

1. Use the DMM to measure the resistance from the black paint (on the CRT) to the silvery metal chassis.

2. Look around the perimeter of the CRT for a copper coloured flat spring that goes between the CRT and the silvery metal chassis.

Quote from: TorZidan on September 28, 2026, 02:24:38 PMCRT televisions and monitors can cause serious injury or death

Thanks for posting this warning; I'll repost it to the Troubleshooting area.

Quote from: sigma7 on September 28, 2026, 05:51:19 PM1. Use the DMM to measure the resistance from the black paint (on the CRT) to the silvery metal chassis.

2. Look around the perimeter of the CRT for a copper coloured flat spring that goes between the CRT and the silvery metal chassis.

Here's a video with my measurements using DMM

https://www.youtube.com/shorts/ixwfd6GJof0

Quote from: berskyboy on September 28, 2026, 06:43:04 PM

Quote from: sigma7 on September 28, 2026, 05:51:19 PM1. Use the DMM to measure the resistance from the black paint (on the CRT) to the silvery metal chassis.

2. Look around the perimeter of the CRT for a copper coloured flat spring that goes between the CRT and the silvery metal chassis.

Here's a video with my measurements using DMM

A couple of hundred ohms seems plausible, depending on where you probe the conductive coating.

So that may mean the copper flat spring is in place somewhere, possible at the right side where the chassis is very close to the tube. If you can find it, please post a picture for reference by future troubleshooters.

Quote from: sigma7 on September 28, 2026, 04:57:24 PMAn upside down CRT might be intended as a warning sign. You've found quite a project!

Fun fact: rotating the CRT 180 degrees was a (recommended) regular maintenance item for Tektronix 4050-series vector storage display computers, intended to preserve the life of the storage CRT. I don't think many people actually did it, and for the 4054 and 4054A, you probably would have wanted an engine hoist to help out with the job.

Quote from: sigma7 on September 23, 2026, 07:36:30 PM(If you're not familiar with AvE, you might find him amusing, although some of the vernacular may be a bit opaque if you're not Canadian.)

By the way.  This guy is hilarious!!!

Quote from: sigma7 on September 27, 2026, 06:12:25 PMExcellent. Before you install them, you should check them with the diode test to make sure they look plausibly like transistors. Measure all 6 permutations of red & black to the 3 connections.

I just got the Q1 and Q2 transistors. 

Measurements as follows (I bought 4, 2 spares)

DIODE TEST           
Red to Black            1, 2                  3, 4
Lead 1 to Lead 2      0.537, 0.536   0.530, 0.540
Lead 2 to Lead 1      OL, OL           OL, OL
Lead 1 to case          0.467, 0.471  0.471, 0.462
case to Lead 1          OL, OL          OL, OL
Lead 2 to case          OL, OL          OL, OL
case to Lead 2          OL, OL          OL, OL

I will have time to put them in the PSU tomorrow.

Quote from: berskyboy on Yesterday at 06:47:32 PMI just got the Q1 and Q2 transistors. 

Measurements as follows (I bought 4, 2 spares)
...

Awesome, they look like NPN transistors!

If you have a sensitive scale, then before you install the transistors, you might consider weighing the ones that you have, old and new.

Counterfeit parts are more and more of a problem these days, and I've seen a post or two on other forums complaining of replacement power transistors that weren't what was advertised. When one poster cut open their new transistors' TO-3 cans, what they found was a substantially smaller and flimsier chunk of silicon inside. Now, as manufacturing processes improve, you might expect the silicon to shrink somewhat over a component's production lifetime, but I assume that for a power transistor this is only to a point. A radical die shrink probably isn't so realistic, as I assume you must have some amount of silicon to conduct current.

For the purposes of this project, you might use this information as follows:
- If the PSU still doesn't work (or soon breaks again) and the new transistors were a lot lighter, you might consider the possibility that you got phony parts and try sourcing new replacements from somewhere else.
- Otherwise, if there are problems and the new transistors were roughly the same weight, you might suspect that there is still another fault elsewhere in the PSU.

Specialised equipment like a curve tracer could tell you more about whether the new transistors were likely to behave like the older ones, but I suspect you don't have one of those. (I wish I did!) Lacking that, weight is one of the few comparative measurements that's easy to take.