Mac plus screen too bright weird stretching

[ßœœ]

So I got it fully working but this is a little weird. Brightness wheel doesn't do much to fix, was this caused by removing the RIFAs? 2nd picture shows stretching/bulging at sides of screen

 

[bibilit]

You have got a potentiometer on the side of the AB board for voltage, have you tried turning it down ?

 

[ßœœ]

You have got a potentiometer on the side of the AB board for voltage, have you tried turning it down ?

Haven't yet, I'll do that tomorrow, I just figured I'd ask cause the bulging on the sides looks really weird, can that be caused by the potentiometer?

 

[bibilit]

unstable voltage for sure, yes can.

 

[ßœœ]

Ok so I adjusted it, the diagonal lines and washed out look are pretty much gone now. Although there is an occasional flicker of lines on the screen, possibly due to noise since the rifas are gone. Also the brightness know on the front doesn't seem to so anything, anyone know why this might be?

 

[Johnnya101]

Probably dirty or maybe bad solder joint. I think if you were to remove the back bucket, remove the cardboard shield thing from the analog board, find the two joints for the knob, use a multimeter and see if the resistance changes.

 

[ßœœ]

Potentiometer works, all solder joints also seem to be good. Not sure to be honest...

 

[ßœœ]

Also does anyone know if this is what unfiltered noise looks like, or is it a bad crt?

 

[ßœœ]

Ok so I didn't pay much mind to this before but can someone tell me what's going on here with the flyback? Is this buildup normal? Looks like rust but I don't think it is.

 

[desertrout]

If you're referring to the blobby stuff on top, that's normal: it's a sealant. It appears yours has done what many high-use flybacks of this era have done and turned brown with age / heat / etc. Your also appears to be cracked. All of which suggests this transformer is nearing the end of This could be the source of your flickering. Are you noticing a ringing sound, or an ozone smell?

If you're referring to the bottom, that does indeed appear to be rust and is not normal, but not uncommon either. I suppose there is a chance that it's interfering with the circuit... but given the overall state of it, you might want to keep an eye out for a parts analog board from a Plus / SE / SE/30 that you can source another transformer from.

 

[ßœœ]

Ok cool thanks! I'll wait till the x and y caps get here and see if they make a difference, but if it keeps up ill see if I can get a new analog board, thankfully they aren't TOO expensive, just enough to be annoying.

 

[desertrout]

They pop up on eBay from time to time for decent prices, just set up a saved search with notifications. When looking at the flyback, check the color of the sealant - if it's yellow (and not so brown), it's likely to be in good shape. Or you could ask here on the trading post.