Imac late 2006 psu 614-0380

[Sylvester]

Re: Imac late 2006 psu 614-0380

I'll get a pic taken tomorrow, I've already had the cover off to measure the mains cap voltage and didn't notice any signs of blown components.

[Sylvester]

Re: Imac late 2006 psu 614-0380

The component next to the mains cap is Q13 K2843.

Next to the 3 caps D16 F20JC10

Another Q2 next to the 2 blue caps K2842

Resistor not sure could be white brown white gold green or grey brown grey gold green, I've attaced a pic of it

The value of the 3 caps are 2200uF 16v x2 and the other as mentioned 1000uF 16v

[Sylvester]

Re: Imac late 2006 psu 614-0380

Pretty sure its white brown white, anyway the dmm shows it to be 0.3 ohms not 91.9 ohms

[Toasty]

Re: Imac late 2006 psu 614-0380

Measured out of circuit...? I think you need a new DMM

White-Brown-White-Gold-Green -is- 91.9Ω @ 0.5% --> REALLY tight tolerance

Resistors go up in value when failed / burnt. This does not appear damaged in any way, especially being a wirewound.

T

[Sylvester]

Re: Imac late 2006 psu 614-0380

measured out of circuit, checked dmm with another resistor, correct value on same scale.

[Toasty]

Re: Imac late 2006 psu 614-0380

Do you have a cap you can sub in for the main cap?

T

[Sylvester]

Re: Imac late 2006 psu 614-0380

No, an oddball value to sub

[Sylvester]

Re: Imac late 2006 psu 614-0380

Quickest to source is 120uF 400v

[Toasty]

Re: Imac late 2006 psu 614-0380

Too close to 390v, needs to be 420v. If you had one to hand, it would be worth a try, but to order, get the correct one.

Again, you can sub 2 in series just to try.

T

[Sylvester]

Re: Imac late 2006 psu 614-0380

420v not easy to source this side of the pond, but we'll get one!

[Sylvester]

Re: Imac late 2006 psu 614-0380

100uF 450v any good?

[Toasty]

Re: Imac late 2006 psu 614-0380

Yup, that's close enough. Voltage can be higher. Capacitance one step down is fine too. Not trying to tune a radio here, just get rid of ripple. What one are you looking at?

T

[Sylvester]

Re: Imac late 2006 psu 614-0380

Need to order this one, prob friday

http://uk.rs-online.com/web/p/alumin...itors/7497256/

[Toasty]

Re: Imac late 2006 psu 614-0380

What series is the original? Elite uses a 2 letter code such as PW.

The Rubycon handles 800mA @ 120Hz. If you can get the 150uF @ 450v which is 8mm longer (40mm vs. 31.5mm) and same diameter (18mm), it gets you another 190ma of filtering.

http://uk.rs-online.com/web/p/alumin...itors/7497265/

T

[Sylvester]

Re: Imac late 2006 psu 614-0380

Its a pw series the others are lyz

[Sylvester]

Re: Imac late 2006 psu 614-0380

The 150uF wasn't in stock, got the 120 uF, will replace tomorrow, tried to check the resistor with another dmm still no reading? May be difficult to obtain a replacement.

The positive leg of the 120uF cap snapped off as it was moved.

[Toasty]

Re: Imac late 2006 psu 614-0380

If you short the leads together, does the meter read zero or nearly zero? Try different scales to confirm.

"tried to check the resistor with another dmm still no reading"

??? You said it was 0.3 ohms ??? (Post 23)

If the resistor is in fact open, then doing the cap will have no effect. You will need to replace the resistor first.

The leg snapping off the cap confirms that the cap leaked electrolyte and that ate through the metal.

T

[Sylvester]

Re: Imac late 2006 psu 614-0380

Replaced 120uF/420v cap with 120uF/450v and refitted resistor, mac powered up (no screen fitted), haven't checked voltages as yet.

The resistor is a mystery, on my 2 meters, 0.3 ohm, on another autoranging dmm it didn't show any value? What's your thoughts on the resistor?

[Sylvester]

Re: Imac late 2006 psu 614-0380

I've just looked at the last figures, seems to be a slight difference in readings,

I'll need to recheck the bridge readings, but the cap is 343v dc off and 386v dc running, out is 12.1v dc.

Replaced the 2200uF and 1000uF caps as well with panasonic fm's.

Got some rtv non corrosive to repot everything and hold the shield in place

[Toasty]

Re: Imac late 2006 psu 614-0380

Excellent. Cap voltages are spot on for standby and boost. That was the culprit.

Elite PW series is one to watch. Replace on sight perhaps.

On the resistor, I don't have a clue as to why except that perhaps the meters are way off or the batteries are low. I would get some resistor values together from low to high and test each meter and compare.

Congrats on getting this fixed.



T