MichaelRD

Q: power mac 5500 noise help

I own a very old power mac 5500, something I got used so I can still play one game.  I don't use it very often, typically 2 weeks out of the year and up until now, it's been just fine.  Lately, I've been hearing what sounds like a bad fan noise.  Soooo, thought I'd take the unit apart and go sleuthing.  I found only two fans, one on the logic board and one larger one below the crt.  With the chassis off, I still couldn't exactly pinpoint where/which/or what was making the noise.  I swapped out the hd, thinking that was the obvious cause.  Still made the fan noise upon starting up.  Took out the fan beneath the crt and still the noise.  Took out the logic board, inspected the small on-board fan and didn't see/feel/hear anything wrong.  With the chassis off, with the hd replaced and the crt fan disconnected, the noise does not seem to be coming from the logic board fan.  So, I'm left to wonder; is there another fan which I can't find?  I inspected the unit pretty thoroughly but still can't figure this out.  Is there a fan housed inside the crt unit?  I also disconnected the floppy disk and cd drive; still have the noise.  Hard to believe it's the logic board fan as the sound does not seem to be coming from there but lower, toward the unit's right side (looking at the front of the tube).

 

Anyway, would like to see if I can fix this, but need some help with possible cause.  Anyone still have one of these or have experience to share?  I did some googling but nothing comes up with such an old machine.  I could take it to a mac repair but wonder if it's really worth it.  I have other options to play the game but the whole setup seems better for my older eyes relative to the smaller screen and serial mouse system of the day.

 

Hopefully someone can point me in the right direction.

 

Michael

Posted on Dec 18, 2014 1:54 PM

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Q: power mac 5500 noise help

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  • by Appaloosa mac man,

    Appaloosa mac man Appaloosa mac man Dec 20, 2014 2:58 AM in response to MichaelRD
    Level 5 (4,330 points)
    Dec 20, 2014 2:58 AM in response to MichaelRD

    Michael,

     

    You are lucky to be so brave.  We had a fellow take six SEs apart.  Each one had a single gremlin.  He wanted to make one of the six work without flaws.  He succeeded in killing all of them.

     

    We have older Macs that we let kids take apart for science projects.  Unfortunately, the cost of shipping the old heavy beasts is prohibitive.  If you are near Seattle, WA  USA, there is a recycler that recognizes the value of history and saves a few older machines in their "AS IS" department.  Finding someone like that is getting harder to do each year.

     

    The most likely fan to go bad is the one in the power supply.  Have you overlooked that?  Is that what you mean when you say 'the one under the CRT?'  If so, the power supply will get hot.

     

    Meanwhile, I will check our supply for ideas.

     

    Ji~m

  • by MichaelRD,

    MichaelRD MichaelRD Dec 20, 2014 7:52 AM in response to Appaloosa mac man
    Level 1 (0 points)
    Dec 20, 2014 7:52 AM in response to Appaloosa mac man

    Thanks for taking a looksee, Jim; I appreciate that.  Unfortunately, I'm in Michigan.

     

    The fan 'under the crt' is truly 'under the crt', housed in a metal enclosure and about twice as big as the one on the circuit/logic board.  I thought the logic board one might be the culprit (and didn't want to do any unsoldering unnecessarily) but when I swapped out the hd and disabled the crt fan, the noise did not seem to come from the logic board.  Also, the logic board fan spins nicely, has no resistance at all and wasn't even dusty/dirty--much.  I cleaned everything while I had it all out, just in case, as I thought dirt/dust was the culprit initially.

     

    Btw, the sound is continuous (except for brief interruptions, as noted below); it doesn't JUST sound bad upon startup.  Even when the comp is asleep, the noise is there.

     

    Anyway, that's why I was asking about something else as it doesn't seem to be the fans, based on my initial search.  Is there any other part that might make a similar noise?  Sure does sound like a fan trying to spin.  Sometimes, there's silence, as if the bearings are unchecked, but then the noise continues soon thereafter.  And it might still be the logic board fan; wish it was more positive of a sound/test, though.  I guess I can replace it and see as it looks easily accessible and I don't suppose finding a fan similar in size and specs would be that prohibitive.  Hopefully you'll come up with something I'm unaware of.  Hopefully!

     

    As noted earlier; I CAN do without this machine but the game just seems to play as I remember, almost 20 years ago now, and I guess getting older, I appreciate that type of experience more than the modern/emulation versions.

     

    Michael

  • by Appaloosa mac man,

    Appaloosa mac man Appaloosa mac man Dec 20, 2014 10:44 AM in response to MichaelRD
    Level 5 (4,330 points)
    Dec 20, 2014 10:44 AM in response to MichaelRD

    Hello Michigan,

     

    My second thought after the power supply was the hard drive.  You said you changed that.  Do you have several spare hard drives?  They are becoming harder to find.

     

    The metal cage is the shroud around the power supply so it sounds like you have eliminated that fan as the culprit.

     

    The next issue you raise is noise detection with the idea of a positive sound test.  An automotive engine sound test is to take a long screwdriver and touch the component that you suspect.  Then put your ear to the plastic handle.  The shaft will carry the sound waves and let you pin point the source of noise.  Unfortunately, that method might be very hazardous to your health because of the high voltage wires around the CRT.

     

    I will take a look at an all-in-one quadra that is easily accessible and see if that prompts any ideas.

     

    Ji~m

  • by MichaelRD,

    MichaelRD MichaelRD Dec 20, 2014 10:09 PM in response to Appaloosa mac man
    Level 1 (0 points)
    Dec 20, 2014 10:09 PM in response to Appaloosa mac man

    Hi again, Jim;

     

    actually, I didn't eliminate the power supply; does that go bad with such a sound?  I sort of thought I'd see issues relating to either working or not working, but sound having little to do with that.  I swapped out the old hard drive and replaced it with a completely different one, just to see if the sound remained, and it did.  So, I figured the original hd was still okay.

     

    Btw, if it WAS a power supply, would I see any performance issues and if so, what type?  The comp works perfectly and I have no issues, other than listening to the fan-like-bearing-failing noise.  I'm just trying to head off a sure problem and need some help.

     

    The metal cage I'm referring to isn't around any power supply but an actual fan; just about double the size of the logic board fan.  I took the fan out and cleaned it, finding no issue when manually spinning.  I also totally unplugged this fan (there are two leads) and kept the comp open, letting any heat get out naturally, but listening to see if my sound disappeared; it did not.  So, I concluded this fan was also not the issue.

     

    With all the casing disassembled, I figured I could hear a lot easier where this sound might be coming from and it does not sound like the location of the logic board but lower down and possibly to the crt's right (if facing the unit).  I looked at all the components surrounding the crt and nothing looks like it might 'spin up'.  Hence why I wondered if one of these components might actually fail with such a sound and I'm just not smart enough to know it!

     

    I've heard it's not a great idea to go poking around a crt based system, so I've been hesitant to do much other than listen and look.  Even taking out the fan that cools the area around the crt kept me careful.

     

    I appreciate your help and hope something else comes to mind.  Barring all else, I'll probably have to let it fail and watch/see what cascades from that event.  But!  Sure does seem like a bearing/fan trying to fail.

     

     

    Btw2; I can take some pics of the area(s) in question, if that would help.  Let me know and I can link to my Flckr account or figure out a way to embed them here.

     

    Michael

  • by Jeff,

    Jeff Jeff Dec 25, 2014 9:43 PM in response to MichaelRD
    Level 6 (11,559 points)
    Dec 25, 2014 9:43 PM in response to MichaelRD

    "Lately, I've been hearing what sounds like a bad fan noise."

     

    Would you describe the sound as a clicking or chirping noise?  If the fans aren't at fault, the culprit could be the analog board.  Failing component(s) on it can produce a a similar noise.  Buying and installing a used analog board taken from a retired 5500 could be a waste of $$, if the part has had a lot of hours of use.  If you wanted to find one, you'd need to know if your 5500 is the original or the Rev. B model.  Parts between the two aren't interchangeable.  The original 5500 has internal speakers that are attached to the front bezel.  If the speakers are attached to the sides of the chassis, it's a Rev. B model. To prevent electrical shock (which can be lethal), I assume that you discharged the CRT, prior to removing the chassis fan during testing?  That's one of the first precautionary steps to perform, before removing the power supply, analog board, video board, cooling fan, etc.

  • by MichaelRD,

    MichaelRD MichaelRD Dec 25, 2014 11:55 PM in response to Jeff
    Level 1 (0 points)
    Dec 25, 2014 11:55 PM in response to Jeff

    Hi Jeff:

     

    The sound is more like a fan having a hard time spinning, as if bearings are worn and it's not turning without some friction.  There are times it seems to stop altogether but resumes the noise thereafter.  Just earlier tonight, I started it up and noticed that the noise did not start until just prior to hearing the tube itself start up (if that's the proper term).  It would seem to me that this noise then is associated with the tube and not the board, but that's why I'm asking.  It also makes me think the larger fan I noted is at fault, but I totally took it out (unplugged both leads) and the noise was still there, sooooo...

     

     

    I'd heard about discharging before and am embarrassed to admit I didn't during my earlier foray.  I've googled and now understand and will employ that technique when I have to take the area apart again.  That said, I didn't go anywhere near the anode 'hole'/junction but did take off the board which plugs into the back of the tube.  There's a good bit of room and I made an effort to not touch much when I was moving the fan out.  But thanks for advising me of the proper way and I'll be more careful in the future.

     

    Btw, the speakers are indeed housed on the front bezel, so that makes this uint is an original.

     

    In the end, should it not be an easy swap out such as hd or fan (or some other easily accessible/obtainable) component, I'll probably have to just trash the comp and play the game on a younger model.  I really did think it was going to be a dirty fan and all I had to do was some cleaning or minimally, replacing.  I didn't think it would be this hard to isolate what surely sounds like a fan about to die.

     

     

    Michael