Re: Quadra 950 Power Supply Went "POP!"

[PeterH5322]

In a message dated 8/26/02 3:54:46 PM, [EMAIL PROTECTED] writes:

<<
My guess, at a distance,is "pop and smell" = transformer which finally 
shorted out, hmm -- based on too many years of rock n roll bands and sound 
studio tech work.
>>

None of the Apples I am familiar with, and certainly not the 900/950/9150, 
which I am intimately familiar with, have a linear power supply; all have a 
switching power supply.

Transformer failures are exceptionally uncommon in "switchers".

The most likely component failure in a switcher is a diode or a capacitor in 
the primary side of the power supply (best case) or the switching transistor 
(worst case). Also the MOV, which is a surge current-limiting device.

Since Q950 power supplies are so cheap these days (the postage costs more 
than the supply itself), it is probably not worth the time and risk to 
attempt to repair the supply.


-- 
Quadlist is sponsored by  and...

 Small Dog Electronicshttp://www.smalldog.com   | Enter To Win A |
 -- Canon PowerShot Digital Cameras start at $299   |  Free iBook!   |

  Support Low End Mac 

Quadlist info:  
The FAQ:
Send list messages to:  
To unsubscribe, email:  
For digest mode, email: 
Subscription questions: 
Archive: 

Using a Mac? Free email & more at Applelinks! http://www.applelinks.com

Quadra 950 Power Supply Went "POP!"

[craig o'donnell]

>Re: Quadra 950 Power Supply Went "POP!"

My guess, at a distance,is "pop and smell" = transformer which 
finally shorted out, hmm -- based on too many years of rock n roll 
bands and sound studio tech work.
-- 
 Craig O'Donnell
Sinepuxent Ancestors & Boats
   <http://freepages.genealogy.rootsweb.com/~fassitt/>
The Proa FAQ   <http://boat-links.com/proafaq.html>
The Cheap Pages <http://www2.friend.ly.net/~dadadata/>
Sailing Canoes, Polytarp Sails, Bamboo, Chinese Junks,
American Proas, the Bolger Boat Honor Roll,
Plywood Boats, Bamboo Rafts, &c.
  _

  -- Professor of Boatology -- Junkomologist
  -- Macintosh kinda guy
 Friend of Wanda the Wonder Cat, 1991-1997.
  _
---
[This E-mail scanned for viruses by friend.ly.net.]


-- 
Quadlist is sponsored by <http://lowendmac.com/> and...

 Small Dog Electronicshttp://www.smalldog.com   | Enter To Win A |
 -- Canon PowerShot Digital Cameras start at $299   |  Free iBook!   |

  Support Low End Mac <http://lowendmac.com/lists/support.html>

Quadlist info:  <http://lowendmac.com/lists/quadlist.shtml>
The FAQ:<http://macfaq.org/>
Send list messages to:  <mailto:[EMAIL PROTECTED]>
To unsubscribe, email:  <mailto:[EMAIL PROTECTED]>
For digest mode, email: <mailto:[EMAIL PROTECTED]>
Subscription questions: <mailto:[EMAIL PROTECTED]>
Archive: <http://www.mail-archive.com/quadlist%40mail.maclaunch.com/>

Using a Mac? Free email & more at Applelinks! http://www.applelinks.com

Re: Quadra 950 Power Supply Went "POP!"

[PeterH5322]

In a message dated 8/21/02 8:06:11 PM, [EMAIL PROTECTED] writes:

<<
I've checked all the sites for troubleshooting, too. I wanna fix this thing; 
not replace it, but I need to know WHERE to start looking for the problem. Is 
it probably in the main transformer, or should I give scrutinty to the 
rectifier?
>>

Most PSU problems are in the primary side, with the bridge rectifier being 
one of the main failure points.

Since the Q (and most other Macs of that era) are auto-switching, you will 
find a relay, a bridge rectifier (or four separate diodes) and two large 
electrolytic caps.

When in 240 volt mode, the primary side acts as a full-wave bridge and 
outputs about 340 volts into the flyback transformer.

When in 120 volt mode, the peimary side acts as a full-wave voltage doubler, 
and also outputs about 340 volts into the flyback transformer.

Either way, the inverter sees about 340 volts dc, and outputs various 
voltages including +5, -5, +12, -12, etcetera.
 

-- 
Quadlist is sponsored by  and...

 Small Dog Electronicshttp://www.smalldog.com   | Enter To Win A |
 -- Canon PowerShot Digital Cameras start at $299   |  Free iBook!   |

  Support Low End Mac 

Quadlist info:  
The FAQ:
Send list messages to:  
To unsubscribe, email:  
For digest mode, email: 
Subscription questions: 
Archive: 

Using a Mac? Free email & more at Applelinks! http://www.applelinks.com

Quadra 950 Power Supply Went "POP!"

[Allen Davis]

Crap.

Just sitting around playing some mp3s on my 9600/G4 the other night, the
"new" Q950 sitting quietly doing nothing, when everyone heard a loud
"POP" that sounded exactly like a .22 pistol going off indoors. That was
instantly followed by that "electrical burning smell."

I almost immediately noticed that the power light on the Q950 was off. I
couldn't get the machine to respond to any kind of start-up procedure.

I have recently replaced the floppy drive with a 24x CD-ROM drive (and
was trying to figure out a way to "bolt it down;" I had the side-panel
off the machine. I have also replaced the stock HD with two of my own --
a 20-gig IBM and 180-gig IBM internal SCSI drives.

A little probing with a multi-meter proves that the power supply has
officially "gone south."

I'm in shock.

I know I got the computer free (I only paid the $16+ to have it shipped
from West Virginia). I stoked up all the RAM slots until it was full.
BTW, this thing DOES have a PPC upgrade because it's been running Mac OS 8.5.

I've been searching high and low for a power supply replacement and am
heartily discouraged by what these things cost!!!

I think I'm even more disappointed that the HEFTIEST power supply Apple
ever made pooped-out on me!!! I mean, this thing is supposed to be rated
at a massive 300-watts!!! It even has extra power output ports on the bottom!

I've checked all the sites for troubleshooting, too. I wanna fix this
thing; not replace it, but I need to know WHERE to start looking for the
problem. Is it probably in the main transformer, or should I give
scrutinty to the rectifier??? I know how to discharge the transformer if
it's still holding any kind of charge. I'm an old hand at discharging
the so-called "throwback transformers in the Compact Macs. No biggie.
I've built power supplies from scratch in the past using nothing more
than an old schematic I got from Popular Electronics magazine from back
in 1974.

But I don't wanna use RADIO SHACK parts!!! I have PLENTY of experience
with their components, and I find they're not always top-notch. I can
get parts from other sources.

I really don't want to lose this Q950 because of a bad power supply. I
lost a highly-prized Q840-AV due to a thunderstorm last year, which
prompted me to buy a couple of APS UPSes.

Someone please help!

Allen
-

-- 
Quadlist is sponsored by  and...

 Small Dog Electronicshttp://www.smalldog.com   | Enter To Win A |
 -- Canon PowerShot Digital Cameras start at $299   |  Free iBook!   |

  Support Low End Mac 

Quadlist info:  
The FAQ:
Send list messages to:  
To unsubscribe, email:  
For digest mode, email: 
Subscription questions: 
Archive: 

Using a Mac? Free email & more at Applelinks! http://www.applelinks.com