IBM CGA card issue

[maelstrm]

Hello, Federation!

I recently purchased an original IBM CGA card. And, well, it has issues.

The display is "distorted". In that, when the machine boots, what should be white text on black has lines of blue mixed in (where only white pixels should be). What's weird is that, if I take a photo, it looks completely normal.

I'm testing this on a 5160 board and a 5153 monitor. The same issue occurs on a modern composite TV signal. I've checked the 5160 motherboard jumpers, and all settings are correct. The issue occurs in either 40x25 or 80x25 mode. I tried adjusting the composite "sweeper" (variable cap?), but this made no difference.

I did notice that one of the tantalum capacitors is swollen (C4), such that the brown coating is torn and a black sphere is "peeking" out. But it doesn't look charred or "burned". Just swollen. This card has the 3-legged C8 capacitor, which looks normal.

The left side of the card has this, which I guess is the model number: YB 110 6133807 01

The value of the damaged capacitor is 106 | 16K.

Any thoughts? I'm not totally averse to soldering some new components. But if its an IC, I may not be able to source it. :/

 

[modem7]

The display is "distorted". In that, when the machine boots, what should be white text on black has lines of blue mixed in (where only white pixels should be). What's weird is that, if I take a photo, it looks completely normal.

Which suggests that the 'distortion' is something in motion, your camera taking a snapshot.

I'm testing this on a 5160 board and a 5153 monitor.

A known-good 5153 ?

I did notice that one of the tantalum capacitors is swollen (C4), such that the brown coating is torn and a black sphere is "peeking" out. But it doesn't look charred or "burned". Just swollen.

The value of the damaged capacitor is 106 | 16K.

Just like C8. See [here].

As for C4, it is one of many capacitors filtering the +5V line. Does the 'distortion' disappear after C4 is removed?


A

 

[maelstrm]

That explains why a camera won't show it, as the distortion isn't present through the entire refresh cycle.

Yeah my 5153 is good. I have an entirely different 5160 motherboard and different IBM CGA card going to it.

I'll remove C4 on this other (just purchased) CGA card and give it a go. I just hope the problem isn't with one of the IC's.

Thanks for the help.

 

[maelstrm]

That did it. Now it has a pretty clear picture, the "blue tinge" is gone. Gonna order up components and get this cap replaced.

Thanks!!!