IIfx won't turn on

[Mike Richardson]

IIfx won't turn on

Tried brand new PRAM batteries in both slots with no success.

Bad power supply? Bad motherboard?

 

[Anonymous Freak]

More description!

What happens when you push the power button on the back? Anything at all?

 

[Mike Richardson]

Absolutely nothing seems to happen.

It is getting power to the power supply, which is plugged into the motherboard. The batteries are inserted correctly and are verified 3.6V each.

 

[Unknown_K]

Yank all cards except video, disconnect the hd and try to boot from a floppy.

Personally if I get a dead system I strip it completely apart and make sure nothing looks bad, then reassemble the basic parts to see if it does run, then if it does put each component back in as needed. Look for leaking caps, overheated parts, missing parts, loose parts, etc.

Could be something as simple as a screw inside shorting out some chip lead, blown power supply fuse, batteries inserted backwards (which was what happened to the dead IIfx somebody sent me last year), cable plugged in backwards, etc.

You will also need a decent handheld digital meter to test things as you go along, I am tempted to get a device to test capacitors.

 

[Mike Richardson]

I pulled all the cards, pulled one floppy (it's a dual floppy with hard drive). The hard drive connects to a SCSI card, not onboard, so it was pulled with the card.

I didn't notice any leaky caps although usually in my experience that manifests it's self as bad/no audio rather than complete failure.

Batteries were installed fine and tested with a meter for 3.6V. I have a basic meter that can test voltage, resistance, etc.

Keyboard is good. Good 120V AC power coming in. Tried a few things like powering on/off and pressing the button, etc. (sometimes makes other Macs work that are kind of flaky).

Motherboard is full of RAM.

I have no other PSU to test with. Maybe I can get a hold of a Mac II/IIx or another IIfx to see if it's the PSU.

 

[Unknown_K]

Open the PS and look for a blown fuse.

 

[KC13]

Pull the ROM SIMM and clean the contacts. That was a common problem with IIfx's.

 

[trag]

Pull the ROM SIMM and clean the contacts. That was a common problem with IIfx's.

Nah, it'll power on without the ROM installed. It just won't do anything afterwards.

A failure to power on is either a fault in the power supply or a localized fault in the motherboard power-on circuitry.

 

[elbaroni]

Does that not make the ROM the problem? I had this problem with my SE/30 a while back. It recurred several times — each time I just took out the ROM simm, wiped the contacts and cleaned the socket. Betcha it works.

 

[Unknown_K]

The original post was from back in January.. problem solved yet?

 

[equill]

Does that not ... Betcha it works.

elbaroni! Good day. Where's yer bin? Not the one yer chucks stuff inna, but yer recent history. Welcome, o Prodigal.

de

 

[elbaroni]

Good day to you too, sir. I had to put all my old macs away for a while, but now they're out and I've got an XCEED card for my SE/30 coming...

 

[trag]

A (physically) dirty ROM may prevent booting and may prevent getting to the point where anything is displayed on the screen, however, it is very rare (I really mean never) that it will stop the machine from powering up. That is, the hard drives spin, there is electricity flowing. The power supply has activated.

The power-on process is independent of the CPU and will operate even if one removes the CPU and the ROM.