If you REALLY want to get into it...
https://www.repairfaq.org/REPAIR/F_monfaq.html

Beware high voltages though, work with one hand in your pocket and the other hand holding a beer, while you yell direction at someone daft enough to twiddle a knob with his knuckles 1/4 inch away from a tube charged to 20,000 Volts...

Edit: Ah the user manual has a circuit diagram at the end though... www.minuszerodegrees.net/oa/OA%20-%20IB ... (5151).pdf

fsmith2003 wrote:

My IBM 5151 monitor which is attached to my 5150 is not working correctly. It does not show anything on the screen and when the brightness is turned all the way up it's just all green with diagonal lines across the screen. Are there any solutions to this that any of you are aware of?

And yes the computer does work. Hooked up to a Tandy monitor it comes up fine.

Err... Tandy monitor is CGA, the 5151 is MDA/Hercules. They share the same connector, but are not compatible. Are you aware of that? If that computer has a CGA card (likely as the Tandy monitor works), then you can not connect a 5151 to it. You need the 5153 or replace the CGA card with MDA/Hercules.

Well somewhat "the point" of buying a Tandy was the better color support at the time, BUT they also did mono monitors, which would have been favoured for business work, spreadsheets etc. It's best to double check though.

Another oddity that can confuse is that there are mono monitors that work on CGA. Usually they're 2 grayscale and drop the other 2 colors. There was a way on some to inverse the colors in case the most important thing you wanted to see was in the wrong pair of colors, but yah it was as much a PITA as it sounds like.

Might be, but he leaves out details which are important. Did the IBM 5151 monitor ever work on that computer? What computer are we talking about at all? Is the Tandy Monitor really MDA/Hercules or rather CGA or even EGA? Etc.

Yes I suppose I should include more details.

The monitor worked just 3 days ago so I know that it does, or did, work with this configuration. The video card inside the 5150 is an aftermarket "hi-res" card that has a switch for selecting mono or color. I do know to change the motherboard dip switches to allow for monochrome or color when using each mode. This is how I am able to use the color Tandy monitor to check that the computer and video card are working. I am able to get a picture in both monochrome and color on the Tandy monitor.

Here is the screen that I am getting so you all can see what I am talking about.

fsmith2003 wrote:

IMG_1596.JPG

Here is the screen that I am getting so you all can see what I am talking about.

It could be either capacitors, voltage regulators, diode (most likely), or flyback transformer. However, I could be mistaken.

Please be careful when servicing a CRT monitor. You can get shocked. My dad serviced CRT monitors at a hospital once, the screwdriver slipped, and got shocked. The nurses said he was lucky that he was at the hospital. Those monitors can hold a lot of volts in the coil for a long time. Also, check the heater to see if it glows in the CRT. I'm about to service an IBM 2115 15" CRT monitor that turns the color straight to pink (still displays text and graphics with no issues) and it looks like oxidation and electronic dust inside the CRT and video display port.