68kMLA Classic Interface

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LC Video distortion after recap

Posted by: elemenoh on 2020-08-02 04:06:37 The recap on this LC went OK (no lifted pads), but video is distorted. The area around all the caps was thoroughly scrubbed with IPA several times. I also removed and cleaned underneath the ICs near the cluster of  caps near the audio I/O. Removing the extra VRAM/DRAM doesn't change the symptom. The distortion will change in pattern a bit when switching between color modes and B/W. I haven't noticed any obviously broken traces, but also haven't looked super closely yet. Is there any area of the board that should be focused on to hunt the issue down?

Posted by: superpete on 2020-09-13 12:03:32 Having a similar issue with a lc575. In b/W you can see the lines which makes me think I've done something to an address line.

Posted by: MrFahrenheit on 2020-09-14 11:15:57 What caps did you use?  Electrolytic or tantalum or ?  What was the rating on them?  If they’re tantalum the resistance and “wobble frequency” matters (can’t remember what it’s called at the moment).

Posted by: superpete on 2020-09-14 20:28:37 I used electrolytic. The voltage was a little higher, but otherwise matched the originals.

Posted by: bibilit on 2020-09-14 22:20:08 broken trace probably

Posted by: techknight on 2020-09-16 21:20:44 yea, likely broken trace or via, or when you recapped, you have blobbed solder over to something that you shouldnt have.  Always double and triple check your work, especially if this symptom was created AFTER the recap.

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