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IBM PS/2 Monochrome Monitor all of a sudden has a white background

haxername

haxername

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https://imgur.com/a/Or2Mkq4

Model 8503
I was using it and it was working just fine, then it just went white on the background (It actually only looks like the bottom half, top half is because of camera).

It still works and I can see everything, But I don't want to keep using it just incase it gets worse. Is this something I can fix and what should I look into. Maybe something popped?
 
Since the tube and high voltage seem to be working, I would go out on a limb and say it could probably be fixed.

First, make sure it isn't an issue with the computer it is connected to. Bad connections happen.

Next, I would probably disassemble and inspect the insides. Clean any potentiometers, check internal connections, check continuity in the video cable, and look for any bad solder joints.

Something that just instantly stops working and does not intermittently work again later, might suggest a bad semiconductor somewhere.

If there is nothing visibly obvious, hunting down a bad component can be tricky, but do-able. From the photo, perhaps something related to the brightness/contrast.
 
Did you accidentally turn up the brightness knob all the way? Or maybe it has dirty contacts and is intermittently shorting out?
 
SomeGuy said:
First, make sure it isn't an issue with the computer it is connected to. Bad connections happen.
Click to expand...
Double checked and its the same thing with another computer
SomeGuy said:
Next, I would probably disassemble and inspect the insides. Clean any potentiometers, check internal connections, check continuity in the video cable, and look for any bad solder joints.
Click to expand...
Slowly taking it apart now. Thank you
SomeGuy said:
From the photo, perhaps something related to the brightness/contrast.
Click to expand...
I think so too, could it be that something is just adding white to the video signal?
 
Those diagonal lines are called retrace lines. It means that the electron beam isn't being turned off fully when the beam goes from the bottom of the screen back to the top. It also isn't being turned off fully when it should be displaying black. Normally you see this if the G2 (often called screen) control is set to high. It could also happen if the cathode voltage is too low, or the G1 voltage is too high. Since it happened on its own, I don't recommend trying to fix it with adjustment.

It could be a bad solder connection, drifted, or open resistor, or a bad capacitor. It's in the age range where any surface mount electrolytic capacitors are likely to be leaking.
 
andy said:
Those diagonal lines are called retrace lines. It means that the electron beam isn't being turned off fully when the beam goes from the bottom of the screen back to the top. It also isn't being turned off fully when it should be displaying black. Normally you see this if the G2 (often called screen) control is set to high. It could also happen if the cathode voltage is too low, or the G1 voltage is too high. Since it happened on its own, I don't recommend trying to fix it with adjustment.

It could be a bad solder connection, drifted, or open resistor, or a bad capacitor. It's in the age range where any surface mount electrolytic capacitors are likely to be leaking.
Click to expand...
What do you mean by an adjustment? Like turning the knobs?
I should be able to replace whichever component is faulty right? Unless, it has leaked and damaged others.
 
Often, in addition to the main brightness control, there's a trimmer pot on the PCB labeled something like "aux bright". I don't know if this is the case for your monitor, however. If so, it's worth checking.
 
haxername said:
Will check when opening
Click to expand...

When open, and you would have the 8503 disconnected from an AC power source when open, do a very good visual inspection of inside (e.g. components and solder joints). You may spot the problem.

Pay particular attention to resistor R425. Why? Because of what I read at [here] for the symptom of "Raster too bright" for an IBM 8503. I am not saying that R425 is the source of your 8503's problem, but given that there is known history of it causing the symptom, it is worth a quick focus. It might not be R425 itself, but one of R425's solder joints. Perhaps first redo R425's solder joints and see if that fixes the problem.
As for measuring R425's resistance with a multimeter, measuring whilst the component is in-circuit can give misleading reading. So I suggest that you remove R425 from the PCB in order to do the measurement. ( Just having one of R425's legs removed from the PCB is enough to effectively disconnect R425 from the circuit).

If the brightness varies when you tap the side of the monitor, that could be indicative of a bad solder joint or dirty potentiometer ('pot').
 
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