IIfx PSU...is it really?

[LaPorta]

My IIfx works well and the PSU was just recapped by me. All is well. The question I have is this: the metal case of the PSU says "Macintosh II Power Supply" on it. I also noticed that I have never seen the fan throttle up or down...which to my knowledge it is supposed to do in the IIfx as necessary. So, do I have a IIfx PSU or one that was stolen out of a II? I don't know if they all say Macintosh II PSU or if a real one says IIfx.

 

[volvo242gt]

I don't remember seeing IIfx written on the Sony branded PSU I had in an fx that I bought from RE-PC in Seattle, WA. I do know that the PSU was dead, so I took the Mac II PSU I was using in another fx that I'd upgraded from a II, and used that instead.

 

[trag]

@LaPorta Did you make or access a parts list for the Mac II power supply? My IIfx was working the last time I powered it up, but it's got to go some time...

 

[LaPorta]

Yes, I did make a full list of the electrolytics in the Sony PSU. Does that help you?

 

[LaPorta]

Well, I'm fairly certain now that I have a Mac II supply: there is no thermostat that I can find. I was reading Pina's Mac II Repair secrets, it appears there were fan thermostat control kits made for these things to upgrade them. What do you think the chance of me finding one from someone on here is?

 

[broccoliwithattitude]

I had a macintosh II. At time they offered to upgrade your machine with a IIfx board. Everything else remained the same. I have run a macintosh IIfx with a II PSU and never had a problem so I guess it’s fine having that in (-:

 

[LaPorta]

Oh I have no doubt it is just fine....I'd just rather not have the thing sound like a jet aircraft whenever I use it.

 

[joshc]

You can put a resistor in line with the fan to reduce its speed, in the Mac II supply. Or try the mod described in that book so its temperature controlled.

Or, put up a WTB post for a IIfx supply. I am pretty sure my IIfx supply does not say IIfx on it. I cannot compare directly with my II supply because that's an Astec and the IIfx has a Sony unit, but I know the IIfx one is much quieter than the wind tunnel version they used in the II/IIx.

 

[volvo242gt]

I wonder which would be louder... A II power supply or a G4 MDD... The II fan was loud, but, bearable. Similar to a 7500 in a hot room. Turn the radio up a little bit, and the noise disappeared. The G4, however, much louder with a dual processor card. Not too bad with a single processor board.

 

[ktkm]

I had to check my IIfx PSU since I never noticed any difference from my II PSU. I took some photos as well.
I can’t tell them apart (component-wise) from the inside, except the fan and grill is larger on the IIfx PSU.

The II PSU has Apple Part Number 699-0389, whereas the IIfx has 699-0393.

To reduce noise, I was considering a Noctua fan.

Top (IIfx)
Bottom (II)



II PSU



IIfx PSU

 

[LaPorta]

I'll have to look inside my case....very similar inside the PSU.

Here is the question: is there something extra attached to one of the fan leads on the IIfx supply? If so, what is it and what does it look like?

 

[volvo242gt]

^looks like the fan in the fx supply is mounted with the wires going the other way than in the II and IIx supply. Also seems like the grille and fan itself may be the only differences, other than the part number. Boards look the same between the two, at least in the photos.