Horizontal lines in crt display, mac 512k—recap?

[mloret]

Just picked up a great deal on a Mac 512k. Fired it up and it works! However there are very faint horizontal lines that show up in the crt display. Will recapping the analog board take care of this? Other idea?

 

[Byrd]

It's most likely the contrast pot up too high, crack open the 512K and you'll see CRT contrast adjustments to dial down a tad.

 

[mloret]

Okay! What's the best way to do this safely? I saw a guy on youtube who did it with a chopstick that he carved...?

 

[LaPorta]

You can do that, or if you foresee doing this on a few of these, there are good plastic sets on Amazon for cheap.

 

[mloret]

Would this work?
https://www.amazon.com/Jonard-TK-AT...M4B&amp&psc=1&amp&refRID=5XN5RE29ACJW57JSTM4B

 

[dochilli]

I use this one:

Adjustment Tips for Electronics Toolkits by jessenator

These are adjustment tips for the common, 4mm hexagonal bit electronics toolkit handles at the following sizes"flat blade 1.0 x 3.0 mmflat blade 1.5 x 3.0 mmhex 2.5 mmhex 3.0 mmhex 3.5 mmhex 4.0 mmCreated specifically for CRT adjustment trim pots on the compact Macintosh analog boards: e.g...

www.thingiverse.com

Can be printed with a 3D-printer.

 

[mloret]

Sadly I don't access to 3d printer.

 

[Byrd]

Seriously, a stick from the back yard will do fine. Just something non conductive that fits in and turns the dial will do.

 

[mloret]

Think it'll break?

 

[Johnnya101]

The board potentiometer won't, as it's made to be turned. The stick shouldn't break either. It's super easy to adjust those analog board pots. I think I have used a wooden skewer once. I bought a set of cheap plastic ones off eBay after that though.

Just take your time in general with these things...

 

[LaPorta]

It shouldn't break, but if you do meet resistance, try wiggling it back and forth...30+ years of dust and such can freeze them, and you don't want to break it.