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cwsmith's picture
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PRAM battery?

First, check the voltage on the PRAM battery. If it's under 3V (original voltage was 3.6V), replace it. They run about $10 at Interstate Battery, or about $16 at Radio Shack.

Next guess would be the PAV board. This takes your wall current and steps it up (to the CRT) and down (to the logic board and drives) to the proper voltages inside the machine. These are pretty common machines, and I'd guess someone should have a PAV lying around. Pretty light and cheap to ship.

Finally, could be the logic board. That would fairly well total the machine back in the day, but again, I'd be surprised if someone didn't have a spare somewhere. Again, light and cheap to ship.

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PRAM

A dead PRAM Battery can cause a total blackout? It doesn't make a sound at all or do anything when I flip the power switch.

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PRAM?

Sometimes, yes.

PRAM stores more than just the date and time. It also tells the computer what drive to boot from, what your preferred screen resolution is, and other information the machine needs to know before it can boot up.

This was particularly true of the early PPC Macs (601, 603, and 604 processors). My 6500, in particular, will not boot at all with a low PRAM battery. No chime, no video -- nuttin', honey.

With no PRAM battery in place, the PRAM will reset to the default factory settings. So ironically, no voltage at all is better than low voltage. Low voltage will confuse the PRAM. No voltage will just make it forget everything.

Chances are that this machine has been sitting, unplugged, for a decent span of time. Just a week in a closet is long enough to drain a PRAM battery. Further chances are that the battery has never been changed anyway -- and 12 years (since the Classic II was discontinued) is well outside the average 3 to 7 year battery life.

It's worth a shot, at least, before looking for more parts.

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Interesting

Thanks, I'll give it a shot when I can find a T-15 screwdriver long enough for the job. No hardware stores in my town have anything sufficient.

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One minute . . .

Hey,

Just how are you trying to turn it on? This is no joke. Please explain how you have it set up.

William
www.williamahearn.com

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Re: Interesting

mi5terdna wrote:
Thanks, I'll give it a shot when I can find a T-15 screwdriver long enough for the job. No hardware stores in my town have anything sufficient.

Try a Sears. They've got a T15 with a 6" shank for about $7.00 US.

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Setup

Well, I've got it plugged right into the wall using that standard 'generic PC' power cable. I then flip the switch, and get absolutely nothing. No sound, no hums, no monitor. After leaving it plugged in a while I thought I heard a quick noise when I turned it on but I'm not sure. I have tried it with and without a keyboard and mouse plugged in. I have yet to leave it in the 'On' position for more than 30 seconds.

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Dead PRAM battery

There are a few Mac models that will not power on with a dead PRAM battery, one of which is the Performa 475.

Strangely enough, my Gateway Astro also will not power up with a dead CMOS battery just to show that PC's are not exempt from the dead battery scenario.

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Raising Lazarus

mi5terdna wrote:
Well, I've got it plugged right into the wall using that standard 'generic PC' power cable. I then flip the switch, and get absolutely nothing. No sound, no hums, no monitor ...

Given both that you bought it on eBay and that the sale was 'as is', it is not an empty suggestion that you get the case open soon. Replacement of the PRAM battery needs that, but you also need to confirm that the other internals are all there. If you have no Disk Tools floppy from which to boot the Classic II, and there is no hard drive inside, you have a significant impasse. No chime indicates that POST is not occurring (or that sound is turned right down), without which you cannot expect to see the grey raster in the next stage. Be aware also that sound level is software-controlled in the Classic/Classic II, and guess where the sound level setting is stored. Be very, very sure that the PRAM battery needs replacement.

A battery needs to measure at least 3.3V of the original 3.67V in circuit to be useful, and below 2.8V puts a battery into the handicap class for many Macs. Start Manager resides in ROM, and doesn't hand over control to the System before a great deal of checking and initialization has been successfully completed, and not-at-all if there is no valid System Folder residing on a functional startup volume with valid boot blocks pointing to the System Folder.

Any Mac that arrives without 'not DOA' warranty must be opened and inspected for the presence of the right number and distribution of its vitals—and in 102% of cases—to replace the PRAM battery, before there is any attempt to wind it up. It also gives the opportunity to clean out the accumulated detritus of years, especially since the Classic II is ventilated through the floor of the case.

de

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The Classic II doesnt need th

The Classic II doesnt need the PRAM battery to start up, just to keep time/appletalk/memory settings.

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What's in PRAM

Not all Macs need all of the following stored in PRAM:

Status of AppleTalk; Serial Port Configuration and Port definition; Alarm clock setting; Application font; Serial printer location; Autokey rate; Autokey delay; Speaker volume; Attention (beep) sound; Double-click time; Caret blink time (insertion point rate); Mouse scaling (mouse speed); Startup disk; Menu blink count; Monitor depth; 32-bit addressing; Virtual memory; RAM disk; Disk cache

but the cost of the battery, and the effort to replace it—since the case must be opened—is trifling in the total process of bringing a Mac in unknown state back to life.

de

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