iMac G5 Power Supply Voltages (i'm a newb)

[theITguy]

i have a friends iMac G5 power supply that i suspected was faulty because her iMac wasn't turning on at all. i've taken the psu out and done voltage tests following this guide here:

http://jimwarholic.com/2010/03/measu...ug-pinouts.php

BUT, after searching about iMac G5 psu's on this forum i've found out that i wasn't testing the voltages correctly, the way i was testing it was just plugging the power into it and then measuring each pin. voltages were either dead on most pins or maybe double the value on some.

could the reason of me getting these stange voltages be because i was testing the stanby power? if so (following this guide) will putting a jumper in pin 15 and 16 power it on so i can test voltages while it is on?

also when using a jumper inbetween pin 15 and 16, do i just have to jump them together for a second to power it on and then again to power it off or leave them linked?

could someone please give me guidance?

[Toasty]

Re: iMac G5 Power Supply Voltages (i'm a newb)

https://www.badcaps.net/forum/showpo...1&postcount=37

Jumper stays in place. 24vsb may read 19-20v in standby but should come up to 24 when jumpered.

Is this an AcBel, Delta, or Celetronix unit?

If AcBel, what is the API number on the case?

[theITguy]

Re: iMac G5 Power Supply Voltages (i'm a newb)

thanks so much for the reply Toasty, i'll test this when i get home!

and how do i find out if it is an AcBel, Delta or Celetronix? this is the first time i've even touched a mac so i wouldn't know sorry.

and if it is AcBel, where would the API number be?

[Toasty]

Re: iMac G5 Power Supply Voltages (i'm a newb)

Label...

[theITguy]

Re: iMac G5 Power Supply Voltages (i'm a newb)

i just did the voltage test with the jumper in it and got these voltages,

1 - 00.0v
2 - 00.0v
4 - 00.1v
6 - 00.1v
8 - 00.0v
9 - 10.6v
10 - 00.0v
12 - 00.0v
13 - 00.0v
19 - 00.0v
20 - 00.0v
21 - 00.0v
22 - 44.3v

what's with these voltages?

and Toasty, it is an AcBel, i can only find 1 number that has API in it:
API4PC46


thankyou so much for your help so far!

[Toasty]

Re: iMac G5 Power Supply Voltages (i'm a newb)

Time to re-cap the unit it seems. Open it up and have a look. Pictures please.

No load on those lines will give false readings, especially when the caps are blown. Takes 15 for a full re-cap sans the 2 mains caps, and a good 45w or better soldering iron.

You'll need a #8 Torx screwdriver to remove the case screws. Check them first though, as some of these use the Security Torx screws with the pin in the middle. There are screwdrivers made for those also. Given the choice between the 2 screwdrivers, buy the Security one.

Toast

[theITguy]

Re: iMac G5 Power Supply Voltages (i'm a newb)

already had it apart, all the caps look good except 1 was slightly bulged, already replaced it though and that never fixed it.

in the first photo you can see the black and gold cap on the right of the board, this is the new one

[lti]

Re: iMac G5 Power Supply Voltages (i'm a newb)

Caps can fail with no visible signs. Out of all the bad caps I have replaced, only two were bulging or leaking. I haven't even tried to work on my parents' old Dell, which has three visibly bad caps and many more that have likely failed. I don't have good enough soldering equipment to recap a motherboard and it is not worth getting professionally recapped.

[Toasty]

Re: iMac G5 Power Supply Voltages (i'm a newb)

Hitano. What series (3-letter code such as EXR or ELR), capacitance, and voltage values?

DMM I assume?

Without an ESR meter, you can't be sure the other caps are good. With all the LTec caps spread about, I'd be very sure more were bad.

[theITguy]

Re: iMac G5 Power Supply Voltages (i'm a newb)

it's EXR 2200 microfarads 10V.

so do you suggest replacing every cap on the board?

[Toasty]

Re: iMac G5 Power Supply Voltages (i'm a newb)

Hitano - EXR - 0.052Ω - 1220mA

Original - LTec - LYZ - (10x23) 0.020Ω - 2365mA -or- (10x25) 0.022Ω - 2400mA

Either way, the replacement chosen is not within spec.

My suggestion would be to replace every cap except the 2 large mains caps which are Rubycon's. I've not seen them fail yet.

Series I use are:

Panasonic: FM, FC
Nichicon: HE, HM
UCC: KY, KZE

As an example using the cap discussed:

Nichicon HM - 10x25 - 0.012 - 2800

[theITguy]

Re: iMac G5 Power Supply Voltages (i'm a newb)

i had no idea ohms cam into specs on capacitors, i only thought you should match the farad values and voltages.

would you mind explaining or maybe post a link explaining these EXR, LYZ, ELR codes and how amps and ohms come into them.

if not that's okay, i'd just like a basic understanding.

[Toasty]

Re: iMac G5 Power Supply Voltages (i'm a newb)

Datasheets for respective manufacturers are the key. That's why I asked for the series code for the Hitano.

Hitano here: http://www.hitano.com.tw/electrolytic.html

Click on the EXR and the datasheet for that series will open. Then find your cap.

Here's LTec: http://www.ltec.com.tw/product_e.htm
-but- they no longer list the original LYZ series. You have to research that a bit (Google) with "ltec capacitors lyz". There's a link to the sheet 2nd one down or so.

This entire site deals capacitors and the problems that have come from the bad ones of several years ago and today. The problems still happen, but the reasons behind it have changed.

A -lot- of reading, but deal with the stickies and FAQ's for a general understanding.

There are TONS of discussions about exactly what you are asking. Here's 2 posts for a good quick read to get you going:

https://www.badcaps.net/forum/showpo...9&postcount=25

https://www.badcaps.net/forum/showpo...9&postcount=27

or the whole discussion: https://www.badcaps.net/forum/showthread.php?t=14079

Toast

[theITguy]

Re: iMac G5 Power Supply Voltages (i'm a newb)

so toast, sorry about the late reply (been really busy lately) but what your saying here is when i'm looking to replace a capacitor i should look up the series code for the capacitor (eg EXR, LYZ) and find out the ripple and impedance of the old one.

THEN

find a capacitor of the same:
-series code
-same capacitance value (farads)
-same voltages
-same impedance value
-same ripple amp value

is this correct?

please correct me i know i have to be really wrong somewhere.

[Toasty]

Re: iMac G5 Power Supply Voltages (i'm a newb)

-series code - No
-same capacitance value (farads) - Yes
-same voltages - Yes - but next higher sometimes yields a better and less expensive cap
-same impedance value - Yes - or better. ESR and impedance are essentially interchangeable for what we do here.
-same ripple amp value - Yes - or better.

See this thread: (PCBONEZ has the silver tongue when it comes to these questions)

https://www.badcaps.net/forum/showthread.php?t=14425

.

[theITguy]

Re: iMac G5 Power Supply Voltages (i'm a newb)

when you say the same or better do you mean a higher value or lower value?

[theITguy]

Re: iMac G5 Power Supply Voltages (i'm a newb)

and okay. so if that's so. i need to find replacements for EVERY capacitor on this board AND they need to match the:
-same capacitance value
-same voltages
-same impedance value
-same ripple amp value

this is more complex then i thought..

i can't even find the first one we discussed, i can't find anywhere a 2200uF 10v (or higher) capacitor with 0.020Ω and 2365mA -or- 0.022Ω and 2400mA

please help

[Toasty]

Re: iMac G5 Power Supply Voltages (i'm a newb)

ESR or Impedance is better when LOWER - 0.020Ω {20mΩ} is better than 0.033Ω {33mΩ}
Ripple handling is better when HIGHER - 2400mA is better than 1950mA

[Toasty]

Re: iMac G5 Power Supply Voltages (i'm a newb)

Any luck figuring it out?

[torgeson5kqs]

Re: iMac G5 Power Supply Voltages (i'm a newb)

I have the same exact power supply and all the information in these posts helped tremendously. I've got the unit to power on when jumpered except there is one voltage that is missing on pin 8. I've replaced Q1 (transistor) which was bad and all the caps that didn't have an ESR within spec using (blue ESR meter) Any ideas on how to get the voltage up for pin 8?

1 - 3.3v
2 - 3.3v
4 - 5.1v
6 - 5.1v
8 - 00.0v ***** This should be 5v
9 - 5.1v
10 - 12v
12 - 3.3v
13 - 12v
19 - 12v
20 - 5.1v
21 - 5.1v
22 - 24.6v