Mac plus Issue

[Retro_GamerC64]

My mac plus screen is too bright and has bright lines going across the screen. I tried adjusting the controls on the back, and the brightness, but it didn’t get rid of it. How can I fix it? The pictures below kinda show it, but I couldn’t get the camera to get a good picture of the CRT.

 

[Byrd]

I'd look first to the CRT adjustment pots, squirt some deoxit or electronic solvent cleaner/lube in and around these.

 

[Retro_GamerC64]

I'd look first to the CRT adjustment pots, squirt some deoxit or electronic solvent cleaner/lube in and around these.

This happened with the brightness, voltage, and cut off in the lowest position it could be.

 

[Retro_GamerC64]

I powered it on today, and now it won’t even make the bong, the screen is just garbled. Could this be caused by bad caps on the analog board?

 

[desertrout]

I powered it on today, and now it won’t even make the bong, the screen is just garbled. Could this be caused by bad caps on the analog board?

Possibly, among other things. Can you share a picture of the screen?

 

[Retro_GamerC64]

Possibly, among other things. Can you share a picture of the screen?

I went and disconnected the LB and plugged it back in and now it is back to what was happening in the above pictures.

 

[goerz]

I went and disconnected the LB and plugged it back in and now it is back to what was happening in the above pictures.

I have a Mac Plus with the same issue. I read on the Dead Mac Scrolls that I should replace resistor R5 (470K ohm, 0.25 watt, 5%) on the analog board. I tested mine and it's 420K ohm: maybe it doesn't mean much, but the drop in resistance is still more than twice its 5 % tolerance. Maybe we found the culprit.

 

[falen6]

i had the same problem with an old SE

recapped the analog board think it would fix it but it is exactly the same

 

[MegaImg]

Their is a Brighness controll on the analog board. Use the nob in the front and put it on high, take the case out and adjust the brightness on the analog board until the lines are not visible.

 

[Retro_GamerC64]

Their is a Brighness controll on the analog board. Use the nob in the front and put it on high, take the case out and adjust the brightness on the analog board until the lines are not visible.

Where is the control?

 

[MegaImg]

Where is the coIntrol?

In the 512K, you have to take the back out, is in the side of the Analog board. You need a flat Plastic tool. Remember, high Voltage. On the white card board attach to the analog board, you will see the Brightness Adjustment.

 

[Retro_GamerC64]

In the 512K, you have to take the back out, is in the side of the Analog board. You need a flat Plastic tool. Remember, high Voltage. On the white card board attach to the analog board, you will see the Brightness Adjustment.

I only saw cut-off and voltage on that side, and neither would go low enough to fix it.

 

[goerz]

I have a Mac Plus with the same issue. I read on the Dead Mac Scrolls that I should replace resistor R5 (470K ohm, 0.25 watt, 5%) on the analog board. I tested mine and it's 420K ohm: maybe it doesn't mean much, but the drop in resistance is still more than twice its 5 % tolerance. Maybe we found the culprit.

So i swapped R5 with a resistor from a working board and the problem didn't go away. Back to the working bench.

 

[MegaImg]

So i swapped R5 with a resistor from a working board and the problem didn't go away. Back to the working bench.

Verify that you don’t have crack soldering points. This is common on this Analog board. Reflow major connector or check with magnification all soldering points for all components.

 

[Retro_GamerC64]

I have a Mac Plus with the same issue. I read on the Dead Mac Scrolls that I should replace resistor R5 (470K ohm, 0.25 watt, 5%) on the analog board. I tested mine and it's 420K ohm: maybe it doesn't mean much, but the drop in resistance is still more than twice its 5 % tolerance. Maybe we found the culprit.

For me that resistor doesn’t have a reading. The legs are also corroded.

 

[MegaImg]

THis is the 512K, but must be similar, you can see top left the Britghness Adjustmen on the analoig board.

 

[Retro_GamerC64]

THis is the 512K, but must be similar, you can see top left the Britghness Adjustmen on the analoig board.

That is cut -off and it didn’t do anything when I tried.

 

[MegaImg]

That is cut -off and it didn’t do anything when I tried.

Got it! If you tap the analog board, any changes...

 

[Retro_GamerC64]

For me that resistor doesn’t have a reading. The legs are also corroded.

Now I got it to read around 4.7Mohms.

 

[MegaImg]

If you tap it and nothing, I have to agree to check / replace resistor R5 (470K, 1/4 %-watt, 5%).