IBM 5153 Streaking Repair

[Great Hierophant]

My IBM 5153 exhibits a problem with streaking with color graphics. Simply put. if a light colored graphic follows a darker colored graphic, there will be a streak of reduced brightness across the lighter color. If anyone has encountered this issue before, I would love to know how to fix it. Other sites talking about this issue suggest checking the caps on the CRT board, but there are a lot of caps inside the enclosure. Last time I checked there were no obvious blown or leaking caps.

 

[nige the hippy]

I've had the cathode drive transistors (often on the tube base board - not sure about the 5153) go duff, or alternatively the drivers to them (next link backwards in the chain) or the pullups, or even the level-adjust trimmer pots oxidise.....
However I'd go with checking / just replacing the electrolytic caps on the CRT base board first anyway, they're probably at-least-a-bit duff (they don't need to leak/blow) the electrolyte disappears over time and the capacitance with it, especially in hot places.
If the drive to the transistors is from a high impedance power source, you'll have the streaking problem, and duff capacitors will raise the impedance.

Hope you follow that!

 

[Lorne]

I didn't check for your symptoms, but I've always found this pretty useful:

http://www.repairfaq.org/sam/monfaq.htm

 

[Great Hierophant]

Way beyond my somewhat feeble electronics knowledge. I wonder if its better to send the monitor to someone who can tune it up or find a replacement. But that site does a good job of identifying the issues with my monitor :

General streaks or lines to the right of bright or dark areas

Red, green, or blue retrace lines (brightness and contrast set near max)

Retrace lines in picture (blue)

Overscan/border blooming