All replacement capacitors in iMac G5 PSU burned up

[nwd]

Re: All replacement capacitors in iMac G5 PSU burned up

For Toasty - no damage on that disc capacitor - just a drip from when the putty was originally applied.

I'm not able to follow the last few technical posts but I gather that it may be likely that other components have been ruined and that fixing this coil will be ineffective for that reason.

-Nate

[PCBONEZ]

Re: All replacement capacitors in iMac G5 PSU burned up

Oh yeah,,,, coffee.. where's the kitchen?

[Toasty]

Re: All replacement capacitors in iMac G5 PSU burned up

Good Morning SUNSHINE!!!

[ran]

Re: All replacement capacitors in iMac G5 PSU burned up

Ran -
I think your best option is to start a new topic for your particular questions and problems. That way you get all the attention from the forum members who can best help you.
<snip>

..will do and sorry!

[i4004]

Re: All replacement capacitors in iMac G5 PSU burned up

first the coffee, then the exhaust pipes on his old car(he'll put used pipes, dunno why) and THEN this!

>Good Morning SUNSHINE!!!



you're serious candidate for gold medal of humor on this forum!

>I'm not able to follow the last few technical posts but I gather that it may be likely that other components have been ruined and that fixing this coil will be ineffective for that reason.

yes, we're speculating about that...for quite a while, actually...

[PCBONEZ]

Re: All replacement capacitors in iMac G5 PSU burned up

..will do and sorry!

I reopened one of your old ones that's related here:
https://www.badcaps.net/forum/showthread.php?t=2737

[Toasty]

Re: All replacement capacitors in iMac G5 PSU burned up

...no damage on that disc capacitor - just a drip from when the putty was originally applied.

Okay! Good.

I'm not able to follow the last few technical posts but I gather that it may be likely that other components have been ruined and that fixing this coil will be ineffective for that reason.

Not at all and not to worry. We are brainstorming and spitballing ideas and theory to figure what is going on, using the info you have provided without any "hands on" for us. Unfortunately, sometimes it requires we go Uber-Geek and lose a lot of people in the dust. Never fear, we'll be right back.............

Think of it as your doctor talking to another doctor. There are words in there that you'll pull your tongue out trying to say.

Has the unreplaced cap been replaced yet?

Did you have any luck finding that coil?

{Post #66} ...says "check voltages" with the PSU disconnected and then connected from the load, what do I need to do...

Using a DMM (digital multimeter - like this***), measure the voltages between the black bunch and the other bunches for starters. Then move on to the individual wires such as the blue and purple ones at the far left. Looking at the wiring harness, you can see groups of colors. They probably all go to the same connection point on the supply.

There are voltages marked on the board from what I see. +12v at the right near the notch, +5.1v down in the middle of those caps in front of the coil. Metering from the black bunch to those points and noting the voltages. Another picture with the wiring harness pulled back away from covering the board and exposing those points where wires are connected would be excellent. Then, when you report the voltages, we can all follow along.

Then, repeat the reading with it hooked up and the computer running so that they can be compared.

{Post #65}...Any chance that it will be a non-AWG gauge...

Yes and No... It probably is a AWG gauge, but might not be a standard or common one. We are used to even numbers such as #22, 20, 18, 16. That coil might use #17. You can get that gauge, as long as you order it in coils of 5,000 feet.

*** DISCLAIMER: Not an endorsement or recommendation of this piece of equipment. Simply a reference to what I'm talking about.

Toast

[i4004]

Re: All replacement capacitors in iMac G5 PSU burned up

back to more important things(all this silly electronics talk...come on):
>Think of it as your doctor talking to another doctor. There are words in there that you'll pull your tongue out trying to say.

you mean like these 2 doctors
http://i4004.net/i4004/?d=python&s=&r=
?
(palin playing one, chapman indeed was a doctor)

[nwd]

Re: All replacement capacitors in iMac G5 PSU burned up

The measurements on the wire were 1mm, .0395in so I think it must be 18 gauge.

I went to an electronics recycler today and looked through a few power supplies. It is a needle in a haystack goose chase to find a matching inductor. I could have opened power supplies all day but they were not keen on that idea and I wasn't really, either.

Unless a supplier can provide a match for the gauge/turns/core dimensions specs I have, I'm reduced to buying a used working PSU as suggested elsewhere and having all the caps replaced on that before something blows.

None of which will solve the mystery of whether replacing this coil will fix the PSU which is what you all have been trying to determine, but I'm stuck.

I will certainly post any developments.

-Nate

[Toasty]

Re: All replacement capacitors in iMac G5 PSU burned up

Good. That makes picking a coil a bit easier.

I too was to the local "Far East Computer Shop" today, looking for broken PSU's & mobo's. They typically collect a pile of broken stuff and the recycler ( guy in a pickup ) comes around once a month to pick it up.

The tech asked me to leave my name and number so that the owner could call me. We'll see what transpires... I may soon have TONS of photos of drippy, leaky, squirting Fuhjyyu's for PCBONEZ and the rest of you.

I'm reduced to buying a used working PSU as suggested elsewhere and having all the caps replaced on that before something blows.

Shame. There was a used one on eBay the other day for $65 including shipping. I don't have any feel for your finances, but that seemed reasonable to me after the time and money you've spent chasing this problem. If nothing else, just to get the system up and running again.

Toast

[i4004]

Re: All replacement capacitors in iMac G5 PSU burned up

hm...hold on.
can he buy new psu and connect it to mac?
that power connector seemed familiar...is it usual atx connector?

and if it's not, why not connect usual atx rails to it?

does mac mobo need some special voltages?

for 65$ he can buy new corsair psu...
sure, it won't fit the mac case, but that's precisely why it'll work at least 10 years more...heh...

afaik, his psu works, so he can easilly find out voltages on that connector...and then he can replace the psu alltogether...

or?

hmmm
http://www.xlr8yourmac.com/systems/A...o_ATX_case.htm
almost...

is this
http://lowendmac.com/video/ports/app...connector.html
even used on that machine?
ie is the passed 28v used?

edit/ seems g5 doesn't have that adc rubbish...

[nwd]

Re: All replacement capacitors in iMac G5 PSU burned up

I've checked into the ATX option - many others have done it. With an ATX extension cable, you can cut off two pins on one end, switch a couple other pins and leave the 24V that powers the display disconnected. Then you need an external monitor which defeats the purpose of the iMac. It is an option, though.

[PCBONEZ]

Re: All replacement capacitors in iMac G5 PSU burned up

Okay so 18 gauge wire.
What is ID, OD, and thickness of core and how many turns of wire?
.

[Toasty]

Re: All replacement capacitors in iMac G5 PSU burned up

See post #65: https://www.badcaps.net/forum/showpo...6&postcount=65

[Toasty]

Re: All replacement capacitors in iMac G5 PSU burned up

After much digging today with the info provided, I'm afraid all the core & coil info won't do any good without the actual "Material #" that the iron powder core is made from. Using the toroid calculator, a T-50 core, 9 turns, the best I could figure it's right about 2.5-3µH. That was using "26 Material".

Toast

[PCBONEZ]

Re: All replacement capacitors in iMac G5 PSU burned up

Thx
I knew I'd seen it somewhere but I couldn't find it.

If the core is not cracked or broken he should be able to coat it with some epoxy paint then then just re-wrap it.
Solid (not stranded) insulated 18 ga wire should work fine too.

[i4004]

Re: All replacement capacitors in iMac G5 PSU burned up

>If the core is not cracked or broken he should be able to coat it with some epoxy paint then then just re-wrap it.
Solid (not stranded) insulated 18 ga wire should work fine too.

yes.

[nwd]

Re: All replacement capacitors in iMac G5 PSU burned up

You guys are pretty amazing.

So I can either paint the core with epoxy paint, then rewrap the core with bare 18 gauge copper wire

OR

Leave the core as is and rewrap with insulated solid 18 gauge copper wire.

Is that correct?

What is epoxy paint?

By "insulated" does that just mean it has a rubber(?) coating around it like the black/brown/blue/purple connection wires on the power supply?

As always, thank you.

-Nate

[i4004]

Re: All replacement capacitors in iMac G5 PSU burned up

>By "insulated" does that just mean it has a rubber(?) coating around it like the black/brown/blue/purple connection wires on the power supply?

yes

>Leave the core as is and rewrap with insulated solid 18 gauge copper wire.

good idea!
<wink>
it's easier to find such wire than to tinker with painting the core etc.

be sure to get solid wire, not stranded...how to tell them apart?
solid is harder to bend and twist...

now, about the capactor (one that you didn't change): i suggest this, though it may look counterintuitive at first:

first just fix the coil, and then monitor the heat(be quick to turn it off is it's still getting hot).
THEN if it's still heating up, change the cap.
repeat the test.

this way we should be able to know what was causing it...
if you change both(ie change the cap, fix the coil) at same time, we won't know what was the cause of coil heat...ie was it coil itself or the cap....


offcourse there are chances neither cap nor coil will solve it, ie tha problem lays on other place...
hopefully this is not so.

btw. why didn't we think of this before?

also, somebody said that particular core type can get permanently damaged by heat?
but it wasn't not the iron type?

[Toasty]

Re: All replacement capacitors in iMac G5 PSU burned up

Not trying to rain on anyone's parade here...

If that cap has not been replaced, you're asking for trouble. See Wizard's post from 2 days ago. Probably the ENTIRE supply should have been recapped.

You can tinker with rewinding the coil all you want. There are some exacting methods to insure this is done correctly. As Wizard tried to point out, it needs to be the correct inductance in this circuit, the amount of turns will not insure that. Wire length, lead length, proper lead tinning, direction of wire wrap, and loop spacing all must be observed. Then it has to be locked in place so the coils won't move.

I'd like to see that coil measured with a proper inductance meter before it gets unwound.

If you decide to DIY, take it out and take lot of pictures from different angles with a ruler in the photo so you'll know if you're close or totally whacked.

If you are really ready to tackle that, there are some sites that will show you how. Look up terms such as: toroid winding guide amateur radio HAM

PDF guide:


More guides:
http://kitsandparts.com/wtoroids.html

Toast

Post #100 in the Thread Expanding Topic