Trinitron Lost Green
 

This may not be the perfect place for this, but it's pretty close. I recently found my old 2000 Trinitron PC CRT. I hooked it up to the MacBook, and boy was it a great display back in its day. It still is.

I turned it on today after 3 days in service, and green is completely gone. This happened once before on day 2, but then quickly went away. Looks like green has lost a connection somewhere, but where? Jiggling the cable does nothing at both ends. I've never seen something like that happen. Where is green? The entire screen has a blueish tint.

The tube is otherwise healthy as the CRT was used very little.

EDIT: Dang it, I meant red. Here's a photo.

http://i1052.photobucket.com/albums/...psfllkk2js.jpg

The tube is fine, as this picture shows:

http://i1052.photobucket.com/albums/...psjdhqm2al.jpg

The cable is captive, so I'm not sure what to do. I'm not sure it's the cable, because no amount of jiggling has returned red with multiple sources.

Most likely a failed cable. They usually break right at the VGA connector.

If you have access to a multimeter, you can check continuity on the red signal wires (usually one of 3 coaxial cables within the larger cable). If you can solder, you could cut the 15 pin VGA plug off, and replace it without too much work.

Otherwise, you need to signal trace the red signal from the input connector pins to the CRT. The signal path is pretty straightforward, and you have the Blue and Green channels to compare voltages and waveforms against....

I don't know how to do those things, but I want to.

First I assume it is best to check continuity. I have a multimeter. How can I check continuity?

Check for continuity between the corresponding pins of the 15 pin VGA connector and the wires inside the monitor. The pinout of the connector is available here:

https://en.wikipedia.org/wiki/VGA_connector

In particular, you want to see that pins 1 and 6 are continuous through the cable. if you look at the cable end inside the monitor, you will likely see 3 coaxial cables for the RGB signals (and maybe 2 more for sync).

Obviously, you do all this with the monitor unplugged from power.

I look forward to trying this tomorrow.

So the back comes off with the power off, one end of the multimeter goes to the pin (1 for red in this case) and the other end goes to the corresponding wire on the circuit board.

Thank you.

Chances are pin 1 or 6 are open.

The cable usually breaks at a point where it is sharply bend or stressed. Usually at the 15 pin plug, or where it enters the monitor.

Other failures are of course possible (red video amp stage somewhere inside the monitor), but broken cables are by far the most common problem here.

Getting the back off of this monitor is impossible.

There are two screws on the bottom that come out, so the bottom part of the back pops out fine. The top part is secured by something that refuses to go. There are two slots on the top that look like this.

http://i1052.photobucket.com/albums/...psr3s1j3oz.jpg

As you can tell I've tried prying it with a screwdriver while pulling on the bottom part. Definite no go. No screws anywhere around the top. What the heck? It's a CPD-E200. Here's a photo of the monitor back.

http://scrapforum.com.au/forum/tv-mo...itron-cpd-e200

Somehow this guy got it open?!

I'm willing to just replace the VGA connector anyway.

How is this done?

EDIT: I'm going to pick up a free CRT on CL to tide me over in the meantime.

Chop connector off end of cable, leaving at least a 1" stub of cable on the severed connector.

Carefully strip the outer jacket off the stub, exposing all the internal cables and wires.

Use an ohmmeter on continuity mode to "ring out" the different colored wires to the individual pins of the connector. It is here that you will likely find one or both of the red signal conductors (likely a coaxial cable) to be open. Compare against the pinout in the wikipedia link to figure out any that ring open. Make a chart of wire color vs. pin number, as you ring the connections out. Check for continuity between the connector shell and the cable shield.

Strip the cable end coming from the monitor, prep and tin the conductors, and solder onto the new DE15HD plug, using the chart you made. If the cable shield needs a connection to the connector shell, you can make it with a short jumper wire, or a twisted bundle of the braid. Install a backshell and strain relief onto the connector, and you should be good to go.

I will be attempting this this weekend.

First step is chopping off the end and testing continuity to see if the problem is indeed with the connector.

Second is to crack open the housing and solder the wires to the connector. However, I don't own a soldering iron. Which one should I buy? There are many different types.

Also, does the cable shield need a connection to the connector shell (is that the metal part?)? What is a strain relief?

I was thinking, would it be simpler to buy a VGA cable and cut it in the middle, and join the two cables?

A utility knife or x-acto knife and some care will work to remove the outer jacket. The wires inside will need a wire stripper.



A temperature controlled iron around 40W or so. These connectors are a bit cramped to be your first soldering project, though. Practice a bit before attempting. RS used to sell the needed parts at one time, but many of them have closed or eliminated their parts stocks. You need a 15 pin male HD connector and a backshell to fit it.

Usually. Check the cut off end to confirm. Yes, that is the metal outer part of the connector. Solder to it quickly to avoid melting the plastic parts.

A clamp or other arrangement to mechanically fix the end of a cable to a connector, preventing excessive strain on the individual connections. A clamp should come with the connector backshell.

It might be, but the colors of wires may not match, and unless you reshield the splice with copper foil tape or whatever, there is the possibility of interference in the image from stray signal pickup.

I really would like to do this right. Maybe I can practice on and solder the stump to a second connector after I make the diagram.

The connector is sealed on the monitor cable. I don't know how I would be able to open it to see if the cable shield is connected to the connector.

To describe this step-by-step from the very beginning, would that be:

1) Plug soldering iron in. Use a wet sponge to get off old solder and tin the tip by putting a little solder on it.

2) Tin the tiny conductors on the connector and on the stripped little wires. Now they both have solder. Wait 60 seconds to cool. Join them together and at the same time put more solder on the joint (just a tiny bit though by quantity, barely thicker than the wire itself). Wait 60 seconds to cool. Repeat for the other remaining wires.

3) Solder a small jumper wire from the shield to the connector metal part.

3) Plug in to test?

4) Put on backshell and clamp.

Thank you again.

EDIT: In this video, he didn't tin the connectors first. Should I do so anyway?

This guide looks closer to what you're saying.

EDIT 2: This video was very helpful.

I'm going to practice on a spare VGA cable and a spare connector, then check for continuity.

...

How do I check pin to ground?

It is strange. No amount of wiggling will make red return. It disappeared, then came back when the monitor switched resolution. Then it was gone for good when I turned it on the next day.

EDIT: Oh, I assume you meant pin 10 (ground). I will check.