Macintosh Plus - Wobbly picture, collapsed height

[joshc]

I have a Plus with a recapped logic board and analog board (work carried out by me).

It worked perfectly before I put it into storage.

I've just taken it out of storage, I think I last turned it on a few months ago.

Now the picture is very wobbly and the picture height has collapsed.

Any ideas as to what is causing this behaviour?

I have checked the ground points and everything is still screwed together as it should be...
 

See videos below



View attachment IMG_0540.mp4



View attachment IMG_0543.mp4



View attachment IMG_0541.mp4

 

[techknight]

They dont play. just show white screens. Should use a service like google drive, or some other uploader/video embedder. 

 

[joshc]

Sorry, they work in Safari but yes don't seem to work in other browsers for some reason

Looks like mp4 embeds are broken on this site maybe.

@techknight Here you go...

https://streamable.com/9h20fk

https://streamable.com/gpmdc6

https://streamable.com/g04h5i

 

[techknight]

thats an open capacitor somewhere. your getting 120hz noise into the horizontal deflection. 

if you have already recapped this board, you should go back and double-check all of your work. And have you replaced EVERY capacitor? including the main primary input filter capacitor? 

 

[joshc]

That seems very odd because after the recap this worked perfectly, its only after being in storage that its had this weird problem.

I replaced all capacitors yes.

I will check them all again...

 

[joshc]

Reflowing the solder joints for the capacitors did the trick. Thanks @techknight

 

[techknight]

Figured. I knew it was an open capacitor somewheres. 

At least you got it going