iMac G4 20” logic Board caps list?

[JimMack]

Just picked-up a non-working 20” iMac G4. Does anyone have a list of the logic board’s electrolytic caps & possibly a cap map? I plan to recap the logic board & power supply once inside. Not alot available online for this rare 1.25 GHz 20” model. Thx

 

[mcbeav]

This is a few months late, but I'll share my list. I just recapped my PSU, and logic board. I did NOT recap the LCD yet, and I don't have what looks like a tiny 2mm SMD cap listed. I didn't replace mine because I missed it, and I'm not 100% sure it is an SMD cap. It looks like it, but I don't know the values of the cap. I will eventually go back and replace it. If you know the value of it, I'd love to know, so I don't have to reopen the iMac to get the values of it.

I don't know if there are different variations, but I have the same 1.25Ghz 20" model, so it's possible there could be some variation with your PSU, or board revision, I have no idea, but here is what I had.

PSU
*The PSU is 2 separate PCBs connected by wires*

Board 1

Location	Capacitance	Voltage	Width	Height	Type
C15	120uf	400V	16mm	36mm	Radial

Board 2

Location	Capacitance	Voltage	Width	Height	Type
C52	1500uf	16V	10mm	27mm	Radial
C53	2700uf	16V	12.5mm	30mm	Radial
C59	470uf	16V	8mm	15mm	Radial
C51	220uf	35V	8mm	15mm	Radial
C55	220uf	35V	8mm	15mm	Radial
C44	10uf	50V	5mm	6mm	Radial
C67	1uf	50V	5mm	11mm	Radial
C38	47uf	400V	16mm	25mm	Radial
C39	22uf	50V	5mm	11mm	Radial

Logic Board

*Some of the silk screen was worn away, so the location numbers might off a number, but I believe they are correct. You won't mistake where they are supposed to go*

Location	Capacitance	Voltage	Diameter	Type	Notes
C295	47uf	16V	6mm	SMD
C349	100uf	35V	6mm	SMD
C338	100uf	35V	6mm	SMD
C339	100uf	35V	6mm	SMD
C354	100uf	35V	6mm	SMD
C355	100uf	35V	6mm	SMD
C356	100uf	35V	6mm	SMD
C269	47uf	16V	6mm	SMD
C245	47uf	16V	6mm	SMD
C19	47uf	35V	8mm	SMD
C1081	220uf	16V	6mm	SMD
C13	100uf	16V	6mm	SMD
C26	100uf	16V	6mm	SMD
C85	47uf	16V	6mm	SMD
C126	47uf	16V	6mm	SMD
C1080	220uf	16V	6mm	SMD
C220	150uf	16V	10mm	SMD	Polymer Low ESR OSCON Cap
C343	150uf	16V	10mm	SMD	Polymer Low ESR OSCON Cap
C357	150uf	16V	10mm	SMD	Polymer Low ESR OSCON Cap
C351	150uf	16V	10mm	SMD	Polymer Low ESR OSCON Cap

*I replaced all of my caps except the tiny one mentioned at the top of the post, but the 4x 150uf @ 16V caps are polymer OSCON low ESR caps. These probably don't need to be replaced. They certainly aren't going to leak, they are NOT electrolytic caps. I assume they used these caps for a reason, so I replaced them with the same low ESR polymer OSCON caps, but like I said, they almost certainly don't need to be replaced. I figure if I'm going to replace the caps, I'm going to just take care of all of them while I'm in there.

 

[JimMack]

Thx brother. I appreciate your help- great stuff. I’d like to help you identify the value of the tiny 2mm cap you referenced above. Specifically, what board is it located on & its location on the board. Cheers!

 

[mcbeav]

Thx brother. I appreciate your help- great stuff. I’d like to help you identify the value of the tiny 2mm cap you referenced above. Specifically, what board is it located on & its location on the board. Cheers!

It's on the logic board. It looks like a cap and has 2 values, but there is no series identifier on it, and I can't find any replacements with the same values. You could obviously use a cap rated for a higher voltage but that has me questioning if it's for sure a cap and not something else. It's near the ports on the logic board, I've circled it in the photo

 

[JimMack]

Thx. I’ll check my logic board & check the cap to see if I can provide the value. It may take a few days, since the unit is in storage. More to come.

 

[JimMack]

C12 is definitely a cap with pos/neg indicators (pic attached). I read it as 22uF, 4V, 3MM diameter SMD. Good luck with the recap. Cheers!

 

[mcbeav]

C12 is definitely a cap with pos/neg indicators (pic attached). I read it as 22uF, 4V, 3MM diameter SMD. Good luck with the recap. Cheers! View attachment 86881

You're the man! Thanks brother I really appreciate the help!

 

[JimMack]

It’s the least I can do. Thank you for the comprehensive caps list.