Can dead battery cause hard disk trouble?

[onlyonemac]

I have a :lc: (Performa 475).

It had a dead PRAM battery, so I had wired it up to a voltage regulator that I had built, powered from a transformer. I then changed that to a similar regulator, but mounted internally powered from a PP3 battery so I could use it with the case cover on .

This is what happened:

Day 1-Mains powered regulator installed, boots fine three or four times that day

Day 2-Battery powered regulator installed, boots fine two or three times

Day 3-Trouble (see explanation below) booting

Day 4+Same trouble experianced

A week or so later-Will not boot, regulator voltage checked and found to be too low

The perpetual problem is, when booting, the hard disk does strange things. Every second time I boot it, it spins up, then, about ten seconds later when it should start booting, it spins down again and shows me a flashy floppy picture. There is no grating or scraping from the hard disk, and it boots from a floppy OK. When it does boot from the hard disk, it works fine.

I then discovered the "double-flick" thing. I tried that, and now, every time, it does "problem". I haven't since tried it with a regulator/battery, so I don't know if that works, but again it does boot from a floppy.

My question is, would getting a new PRAM battery fix the problem. I say this particularly because the problem only showed up after a while (battery voltage dropping over time).

P.S. Don't say my hard disk's bad, because I haven't got another!

 

[spiceyokooko]

I just do not understand peoples irrational fear of PRAM batteries - it's almost become an epidemic!

The reason PRAM batteries (and any other type of battery of that type) explode, leak, cause damage etc is because they're OLD! It's not because the batteries within themselves are inherently dangerous. Almost every piece of electronic equipment that uses these type of batteries all advise that if you do not intend using the device for any length of time to remove the batteries. That seems a pretty good piece of advice to me and it applies equally to old computers as it does to any other piece of electronic equipment. Yet so few people seem to bother follow this simple piece of advice - and are then surprised when damage occurs.

To solve your problem - replace the PRAM battery with one of a similar type. Most of the PRAM batteries used in Macintoshes are Lithium 1/2 AA 3.6v - these are easily obtained on places like eBay for a couple of bucks. Save yourself a lot of time, trouble and messing about and replace the PRAM battery and remove it if you don't intend using the machine for any length of time AND replace it once it's gone beyond its useful shelf life.

Simple!

 

[onlyonemac]

I know I could replace the battery, I was just wanting to know if that would fix it before I waste my money/time. I have no fear of PRAM batteries, just wanted to know if that would solve it.

Keep posting!

 

[onlyonemac]

I meant to say that I would like to know why it won't boot with a double flick, as I have heard that that works, and I wouldn't have to buy a battery :lol: .

 

[spiceyokooko]

You need to try and understand why the voltage is dropping.

In my opinion from what you're written, the Hard Disk isn't getting sufficient power from the board to continue working and that's why it's spinning down.

From the limited information you've given, if the voltage is dropping and there is insufficient power to keep the HD spinning, you may have bad capacitors, because that's a typical symptom of bad caps.

That's just a stab in the dark from the information you've given - it could be a lot of other things as well.

 

[onlyonemac]

Um... the voltage drop is from the regulator that pretends it's a battery. That's not what powers the hard disk is it?

I can't really give much information as I'm a newbie to old macs.

 

[Charlieman]

If it starts to boot, the PRAM battery is unlikely to be your problem.

It looks like you have a faulty PSU or that something in your 475 is sucking up a lot of power on boot. Have you tried booting from floppy disk?

Edit: Isolate the problem. Fit a new PRAM battery.

 

[spiceyokooko]

Edit: Isolate the problem. Fit a new PRAM battery.

Yep, already advised that!

You can speculate and theorise till the cows come home, at the end of the day you have to start proving or disproving some of these theories and you can't do that if you have 'unknowns' in the mix.

It may well be a faulty PSU, but variable and inconsistent startups are often due to the board capacitors not holding any or little charge and that sucks power out of the board causing inconsistency. You won't know that of course until....you replace the PRAM battery!

Full circle!

 

[onlyonemac]

I'm pretty sure it is the PRAM "battery", as it was when I used the battery-powered regulator for it that trouble was starting, and it was only when that ran down that the mac's hard drive caused trouble every time.

variable and inconsistent startups

The startups are not inconsistent. I have read about people who say it their mac starts up "about every third time, although today it started up twice with no trouble". I did at the time find it strange that my mac always started up fine every second time, with the alternate time causing the exact same trouble every time. It never deviated from this pattern, even when I had left it for days. I even did a cold restart and it did it again :lol: !

Now, when I do the double-flick thing to start it, the hard drive never works properly. I have read in Wikipedia that the double-flick works on this very model. My question is, why does it never work (the mac boots from a floppy and the video does start up, but the hard drive doesn't work).

Finally, I have included a detail of each kind of startup my mac goes through (I have not timed this accurately).

Successful:

0 sec-power switch flicked, fan and hard drive spin up

2 sec-startup chime

5 sec-breif hard drive and fan dip as video starts up, normal fan/hard drive sound restored

13 sec-hard drive starts clicking

15 sec-happy mac, "Welcome to Macintosh"

17 sec-extensions start loading

25 or 30 sec-main desktop appears and mac is now usable

Unsuccessful:

0 sec-power switch flicked, fan and hard drive spin up

2 sec-startup chime

5 sec-breif hard drive and fan dip as video starts up, normal fan/hard drive sound restored

13 sec-hard drive spins down

15 sec-blank grey screen with moveable cursor

17 sec-floppy disk with flashing "?"

Unsuccessful with bootable floppy:

0 sec-power switch flicked, fan and hard drive spin up

2 sec-startup chime

5 sec-breif hard drive and fan dip as video starts up, normal fan/hard drive sound restored

13 sec-hard drive spins down

15 sec-happy mac, "Welcome to Macintosh"

About a minute later-main desktop appears, mac is usable, but hard drive is not present on desktop and is not recognised by "disk first aid" or any other programs on the utility disk

Double-flick:

0 sec-power switch flicked, fan and hard drive spin up

2 sec-startup chime

5 sec-hard drive spins down

6 sec-power switch off (sometimes I do this before hard drive spins down at 5 sec)

7 sec-power switch on again, follow unsuccessful startup from 0 sec

I know this is rather long, and I know I could replace the PRAM battery, but I just want to know why it won't boot when I do the double-flick thing and if there's anything I can do about this .

 

[onlyonemac]

UPDATE:

This morning I tried to boot my mac again. I was actually trying to test a system 6 boot disk that I have been trying to make for a while.

I tried it 3 times with a floppy. Each time, it booted as for a double flick startup, then it proceeded to read the disk. Then, I got this:

xx(

00000F

000001

The second time it booted, I think I briefly saw a :b&w: , but I'm not sure.

On the third try, my hard disk started clicking. That's one time in about 8-10 times sice trouble struck. I couldn't see if it would mount it, however, because I had my bad boot disk in the floppy drive, so insted I got the sad mac. I then, of course, tried it without the floppy, but the hard disk did is usual thing.

I'm not sure what the codes mean, and there was no chord sequence, but I don't suspect the sad mac to be a hardware fault, as it did not happen when I tried it without the floppy.

This is just an update, much help would be appreciated, as it is still not working properly.

P.S. If you could help me make my boot disk, that would be helpful too

 

[Charlieman]

onlyonemac asked:

I know this is rather long, and I know I could replace the PRAM battery, but I just want to know why it won't boot when I do the double-flick thing and if there's anything I can do about this.

Every time that you boot the Mac and it gets as far as looking at the hard disk, the Mac logs the fact (on the disk) that it tried to boot. With System 7.5 (?), Mac OS looks at the log and if there are failed boots, it flags the disk for repair. Boot will be slower.

Given that you only own one Mac, you are asking for trouble by experimenting in this way. Sooner or later, the hard disk will stop booting.

Quick-flick on the power switch is a diagnostic method for identifying whether a Mac might work before replacing the PRAM battery. Having verified that the Mac works, sane people replace the PRAM battery.

 

[onlyonemac]

Quick-flick on the power switch is a diagnostic method for identifying whether a Mac might work before replacing the PRAM battery. Having verified that the Mac works, sane people replace the PRAM battery.

I have heard that people use this on this very model all the time!

 

[LCGuy]

The thing is, yes, it can be done, and it can be used as a long term "fix", however given the extra wear and tear you're putting on the machine...there's no real point in it when you can avoid it by spending all of $7 on a battery.

 

[nvdeynde]

When a hard drive starts spinning up and down at power on, there are 2x obvious reason.

Either the heads are stuck in the parked position and repeated attempts free them.

Other possibility is that the PSU is not giving enough power, probably due to failing capacitors.

Given the age, both the logic board and the PSU need to be recapped.

I don't think that a new pram battery will be enough to solve your problem.

 

[onlyonemac]

I don't think that a new pram battery will be enough to solve your problem.

I thought the same this morning .

Earlier today, I connected another voltage regulator to the battery slot. This one was powered from a small transformer, but had a power jack on it so that it could be mounted internally.

Startup was the same as with an unsuccessful startup from the list above. I tried it three times with the same result.

I don't think that it needs recapping, as there are no signs of cap crap on the mother board. I have tried reseating the hard drive power and SCSI connectors with no change.

Anymore suggestions? :?: :?: :?:

P.S. I don't have time/money to spend on recapping/PSU change/new hard drive, but please suggest anything other than those standard and overmentioned fixes.

:'( :'( :'( :'( :'( :'(

I love my mac!

 

[nvdeynde]

P.S. I don't have time/money to spend on recapping/PSU change/new hard drive, but please suggest anything other than those standard and overmentioned fixes.

The "overmentioned fixes" are the only solution. Electrolyte Capacitors degrade over time: that's just basic chemistry. Leakage is not always obvious, they can also dry out or don't leak at all while they are bad. You need an ESR meter for testing capacitors.

Since your performa 475 is at least 16 years old, it's likely failing capacitors that cause the problem.

You may not like my answer but these "standard" fixes do solve the problem in 90% of cases like yours.

I have rebuild my IIsi PSU a while ago, it's 3 years older than your performa 475, but the PSU was a mess inside with many leaking capacitors.

Also you are looking at the logic board: the problem is most likely the power supply.

If you don't want to go this way and spend money to keep your computers in working condition then I would suggest looking for another hobby...

Sorry,

Nico

 

[onlyonemac]

I can't really even check the capacitor's in the PSU, as I am inexperianced enough with mains voltage circuits. If you can help me there, please feel free to do so. Maybe once I've finished my own PSU project I'll be more confident.

Speaking of other PSUs, is there any way that I can try my computer with a different supply (I don't know about the power connector pin mapping either). If that works, I might want to try recapping my PSU, otherwise I won't bother with that.

P.S. Old macs is not my hobby-I was just given an unloved mac.

 

[onlyonemac]

UPDATE:

I have measured the voltage coming from the PSU. These are my results:

Under no load:

-Blue wire: -4.8v

-Yellow wire: 11.11v

-Orange wire: 5.27v

There is also a tick about twice a second-it seemed to speed up as the supply was running for a while.

Under load when powering mac:

-Blue wire: -5.06v

-Yellow: 12.3v

-Orange: 5.1v

The tick is not present when the supply is under load (I disconnected the fan and hard drive so I could hear if there was a noise)

In both cases, my meter has a 1M ohm impedance.

 

[mcdermd]

Recap it.