Prepping a 512K for use

[redrouteone]

I have a Mac 512K, which has been sitting on my display shelf for the past 5 years.

I got busy and forgot about it, and it just sat there. I finally got a set of disks to boot from. I don't want to just plug it in, turn on the power, and stick in a disk.

Sitting for so long it might need caps. Would opening it up and visually inspecting them be sufficient?

I'm sure the drive will need to be cleaned. Any recommendations, other than tracking down a floppy cleaning kit?

 

[uniserver]

i'd plug it in, Slap a disk in, see what happens,

i bet all is well.

i just wouldn't do it in your bunker. Maybe take it out in the garage, just incase a HV filter caps goes. Those can to go bang in a cloud of smoke.

 

[RickNel]

The classic recommendation on bringing up a long-dormant vintage item is to first "condition" the old caps by bringing the thing up on a slowly increased AC voltage - but this assumes you have access to a variable AC supply, which most of us do not. The thing is, if caps are near end of life, they will go sooner or later anyway. So Uniserver's smoke test is probably as good as any.

Rick

PS Krye's next post is very sensible!

 

[krye]

I'd definitely open it up and take a look to make sure caps haven't leaked everywhere before powering it on. That stuff's conductive. You may do more harm than good turning the machine on if there's ooze all over the place. You can short out surrounding components. At least make sure it's clean inside. Make sure the PRAM battery hasn't leaked everywhere too.

As standard practice, I always open and inspect the inside of a vintage Mac before powering it on for the first time.

 

[James1095]

The classic recommendation on bringing up a long-dormant vintage item is to first "condition" the old caps by bringing the thing up on a slowly increased AC voltage - but this assumes you have access to a variable AC supply, which most of us do not. The thing is, if caps are near end of life, they will go sooner or later anyway. So Uniserver's smoke test is probably as good as any.

This applies to linear power supplies, particularly in antique (as in full of vacuum tubes) radio and TV sets. It is *not* advisable to operate anything with a switchmode power supply at reduced line voltage. The better designed ones will lock out and shut down, but some will crank up the duty cycle struggling to maintain output until something blows up.

In ~2 decades of working on this sort of stuff, I have *never* had a problem just powering something up. It is advisable to have a peek inside first to make sure it's not full of bugs, dead rodents, pee, water, metal filings, and other such things but assuming it passes the quick visual exam, plug it in, flip the switch, and be ready to kill the power if you see smoke or sparks. It's not a bad idea to replace caps that are known to fail, but unless they are obviously damaged, I normally check it out first, if it works perfectly, chances are the parts are fine.

 

[uniserver]

I love it when you flip something on and then " fireworks " haha

 

[markyb86]

It is advisable to have a peek inside first to make sure it's not full of bugs, dead rodents, pee, water, metal filings, and other such things but assuming it passes the quick visual exam, plug it in, flip the switch, and be ready to kill the power if you see smoke or sparks.

I love finding electronics full of pee.

My stash of Pentium 3/4 motherboards were in a shipping crate in the basement. The resident border collie here kept having accidents in the living room. eventually they did enough of a number on the floorboards and the pee made its way into the basement, right into that crate of Pentium boards.

When it was too late to realize, I went in there looking for some blank RDRAM sticks, and voila, everything was ruined. Now that dog lives in the kitchen (which there is nothing underground under, and also has linoleum flooring...)

Although this site has its horror stories to scare me otherwise, I always just inspect and power up as well.

 

[Byrd]

When powering up a dodgy looking piece of equipment, I plug it into a surge guard first, and stand back with a stick and turn it on from mains. Funny thing is, machines I've done the "stick test" to usually work fine, but it's the normal clean looking ones that often emit the magic smoke!

 

[RickNel]

@Byrd

stand back with a stick and turn it on from mains.

Great image :lol: Vintage computing meets lion-taming

Rick

 

[Timbo]

I actually like to see some smoke when I turn a dodgy computer on- means trouble shooting is so much easier!

(before I knew any better they used to go straight to the bin when I saw a puff of smoke! )

 

[CelGen]

Plug it in and see what explodes.

 

[volvo242gt]

God knows how long my 512Ke sat dormant. Probably at least 8-9 years. Was in the previous owner's basement for years. Plugged it in, slapped a System 1.1 disk into the drive, and hit the switch. Booted right up, without issues. Most of the 68000 machines were that way. The only ones that weren't: one of the 512K's, which displayed a permanently happy mac icon, an SE that kept ejecting whatever disk I'd pop into it, and a Classic that worked fine for a couple boots, then started checkerboarding. The Plus also had some slight issues, consisting of an analog board that only allowed a vertical line to show on the display. The SE/30's, a couple worked, but had no sound, thanks to bad caps, one powered up, but did the usual SimasiMac, and a third just displayed a blank screen (the one that had the exploded Tadiran battery). Classic II, SimasiMac as soon as it was powered up.

The older 68000 compact Macs seem to be fairly robust, so, pop it open, do a quick visual, then put it back together and power it up. After all, the one that Maceffects Mark owns hadn't been powered up since 1992.

-J

 

[James1095]

I love finding electronics full of pee.My stash of Pentium 3/4 motherboards were in a shipping crate in the basement. The resident border collie here kept having accidents in the living room. eventually they did enough of a number on the floorboards and the pee made its way into the basement, right into that crate of Pentium boards.

When it was too late to realize, I went in there looking for some blank RDRAM sticks, and voila, everything was ruined. Now that dog lives in the kitchen (which there is nothing underground under, and also has linoleum flooring...)

Few things around the house are more corrosive than cat pee. I haven't had it happen often, but I did once have a cat who would pee in specific places as his way of informing me that the litter box was not up to his standards. Once or twice it happened to a box with electronics in it, thankfully nothing too valuable because it looked like the result of a PRAM battery explosion. Yuck!

 

[uniserver]

so did you ever fire this thing up and see what happens?

 

[redrouteone]

No I haven't been tied up with with other stuff and forgot about this.

 

[redrouteone]

Well I finally got a chance to look at the 512K.

Plugged it in, bong,...... nothing on the display.

Looks like I'll need to crack it open and take a look at the analog board and see what's up.

 

[unity]

Well I finally got a chance to look at the 512K.
Plugged it in, bong,...... nothing on the display.

Looks like I'll need to crack it open and take a look at the analog board and see what's up.

First check the overlooked dim dial. It can be turned way down, easy to do when handling actually. Second, give it a smack on the left side. You might get a flicker of life or it may stay on - but if it does, turn it off. It means there is a cracked solder connection. This is very, very common and easy to fix. The most common areas for solder cracks are where cables enter the board. The plugs. They LOVE to crack. Same applies to the motherboard. Though less common, they can crack here too. Some quick soldering will take care of it. The problem is that if you get the screen to work after smacking it, the solder joint can arc just a bit causing a lot of heat and thus melting/burning the plug.

 

[redrouteone]

Checked the dial, it was the second thing I tried. (The first was turning it off and back on again). I also tried slapping it, no go.

 

[unity]

Checked the dial, it was the second thing I tried. (The first was turning it off and back on again). I also tried slapping it, no go.

Well pop it open and check the solder joints at the cables. I bet its the issue. The fact you get the tone means at least the analog is working enough to power the logic board.