Recap and open IIfx power supply

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Recap and open IIfx power supply

Does anyone have anything that explains how to recap  and open an Apple Mac IIfx power supply?

 

I have searched high and low and cant find anything.

 

Thanks!

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Carefully inspect your

Carefully inspect your motherboard before you go to the trouble.  From what I've read most of these units have suffered catastrophic damage from leaking components like electrolytic capacitors and may not be repairable.

 

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softwarejanitor wrote
softwarejanitor wrote:

Carefully inspect your motherboard before you go to the trouble.  From what I've read most of these units have suffered catastrophic damage from leaking components like electrolytic capacitors and may not be repairable.

 

 

Thanks! Already went through my IIfx as its brand new and works perfectly. After using it for about amonth I heard a loud pop. Everything still works perfect except I think one of the RIFA caps went kablooey!

 

So I want to fix it

 

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retro_bill wrote
retro_bill wrote:
softwarejanitor wrote:

Carefully inspect your motherboard before you go to the trouble.  From what I've read most of these units have suffered catastrophic damage from leaking components like electrolytic capacitors and may not be repairable.

 

 

Thanks! Already went through my IIfx as its brand new and works perfectly. A

You're lucky if a RIFA cap blew and didn't take something else out with it.  Those are easy to replace.  You don't really need any guide to do it.  Just open up the power supply, look at the values printed on them, buy replacements, de-solder the old ones, solder the new ones in.

 

I'd inspect any electrolytic capacitoes for signs of bulging or leaking and replace them.  Other than that look for signs of any parts that look like they are burned or have been getting hot.

 

Anyway, from what I gather, you are lucky to have a IIfx that still works, as many of them have failed over the years.  That era models II -> IIfx are apparently very susceptible to motherboard failures.

 

 

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Removed my brand new power

Removed my brand new power supply.

 

Opened it up and everything still looks brand new.

 

Where is the RIFA?

 

How do you get the PCB out of the case to do the RECAP?

 

THanks!
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I don't see any RIFA caps in

I don't see any RIFA caps in there.  Honestly if that power supply is working I wouldn't recommend doing anything to it at all.  Re-capping may be more dangerous than leaving it.  I don't see any evidence any of the electrolytics in there are leaking or bulging.  Are you sure what you smelled came from the power supply and not somewhere else?  Because I don't even see anything in there that looks like it has gotten hot.  Does the power supply smell like burnt now that you have it open?

 

 

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This PSU is too new to have

This PSU is too new to have RIFA caps, considering they stopped using this brand 1988. But if it did, one would be in C101's place, which looks like the mains RF filter capacitor (X2) that sits directly between the line and the neutral. Your Y1's are probably the yellow capacitors in the top right corner. Also RIFA caps don’t usually go pop, they go BOOM and then you have this thick brown stinky molasses everywhere.

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softwarejanitor wrote:I don't
softwarejanitor wrote:

I don't see any RIFA caps in there.  Honestly if that power supply is working I wouldn't recommend doing anything to it at all.  Re-capping may be more dangerous than leaving it.  I don't see any evidence any of the electrolytics in there are leaking or bulging.  Are you sure what you smelled came from the power supply and not somewhere else?  Because I don't even see a

 

 

I do not smell anything in the power supply and cant see anything wrong and the IIfx works perfectly.  I heard a pop and and smelled something but the only thing that no longer works after the pop is the BlueSCSI. Other than that I can not see anything wrong and there is no smell to be found anywhere in the IIfx.

 

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persistent

Rifa metallized-paper capacitors have a very persistent, "sticky" smell after they explode, something like burning hair. In one case I had a smell in the corner of the room for months.

If the smell is now gone, it must have been some other material that burned, perhaps a transistor or diode, or even a tantalum capacitor.

Are you sure that every function of the computer still works? What about the serial ports? (They are one of the few users of negative supply voltages like -12.)

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He said at least one SCSI

He said at least one SCSI device wasn't working...  might have blown it, or something on the motherboard.

 

It depends on whether other SCSI devices work.

 

 

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softwarejanitor wrote:He said
softwarejanitor wrote:

He said at least one SCSI device wasn't working...  might have blown it, or something on the motherboard.

 

It depends on whether other SCSI devices work.

Replaced the BlueSCSI with a SD2SCSI and works great! So SCSI is working. As far as I know everything seems to be working.

 

 

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I would leave the PSU alone

I would leave the PSU alone if everything is working. Just remove the hot melt silicone from the vents of the electrolytic capacitors.

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retro_bill wrote
retro_bill wrote:
softwarejanitor wrote:

He said at least one SCSI device wasn't working...  might have blown it, or something on the motherboard.

 

It depends on whether other SCSI devices work.

Replaced the BlueSCSI with a SD2SCSI and works great! So SCSI is working. As far as I know everything seems to be working.

 

The evidence of what you are saying seems to point to something on the BlueSCSI itself being what burned and caused the smell if it is the only thing that is suddenly not working.  You might look at it to see if any components show signs of failure.

 

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CVT wrote:I would leave the
CVT wrote:

I would leave the PSU alone if everything is working. Just remove the hot melt silicone from the vents of the electrolytic capacitors.

 

I'd concur.  Probably better not to mess with it too much.  It's really pretty clean other than all that hot glue.

 

 

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