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IIfx acting funky, can't get it to boot right

M

MysteryManBob

6502
I just got my hands on a new IIfx upgrade board (not the one that just sold on eBay for 600, I actually lost that) from an old Apple dev I met on Facebook. The thing was pristine but of course I recapped it to eliminate variables, and after getting all the parts together it's not booting. Instead what happens is the power supply comes to life, and the two floppy drives start firing off like crazy and chirp wildly for a second. There's no boot chime or death march chord, and the speaker/psu/drives all worked fine when this was still just a IIx.

Any suggestions? I'm getting desperate to get the thing working. I haven't found anyone else online with this issue and all the books including dead Mac scrolls couldn't give me anything either...

 
I'd try disconnecting everything (including floppies and HDD) except one bank of RAM and the video card.  Remove the ROM SIMM, clean the contacts with a pencil eraser, and place back.  Try the board out on an insulated surface to make sure it isn't shorting out on the case shielding.

 
joethezombie said:
I'd try disconnecting everything (including floppies and HDD) except one bank of RAM and the video card.  Remove the ROM SIMM, clean the contacts with a pencil eraser, and place back.  Try the board out on an insulated surface to make sure it isn't shorting out on the case shielding.
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image.png

no raster, no chime, still not getting anywhere, I'm gonna start reflowing pass-thru legs that may have gone cold because until I get more ram to play with I can't really do anything 

 
Kind of off-topic but don't all IIfx motherboards have two PRAM batteries - I can only see placement for one on your board?  Certainly the IIfx will not boot without good PRAM battery(s) installed.

 
The other battery is there in the picture, barely peeking out from behind the last (first?) SIMM.

Could you post a hi-res picture of the MB from directly overhead and also one of the ROM and SIMMs with the part numbers showing?

Did it come with electrolytic caps?

Did you replace all the caps, including the axials?

Did you wash the board?

 
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Byrd said:
Kind of off-topic but don't all IIfx motherboards have two PRAM batteries - I can only see placement for one on your board?  Certainly the IIfx will not boot without good PRAM battery(s) installed.
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Juror22 said:
The other battery is there in the picture, barely peeking out from behind the last (first?) SIMM.
Click to expand...
yea two new batteries are in there, this actually came with its factory batteries completely intact. I rushed them out and got these in here. again the board was totally clean and pristine as I received it. a minute ago I discovered one of the caps I replaced had a lifted pad and broken trace, so I bodged it to its nearby connection to a resistor. the only thing that changed was that now when I press the button it powers on the first time instead of the second or third. still it didn't help the main issue I'm having and I'm kinda back to square one

 
Alright, I can just see the other battery hiding there!  I'd agree with Juror22, time to (dish)wash the board or at least clean well around the caps you've replaced with isopropyl alcohol.  You'd not expect much capacitor leakage from a IIfx as only a few axial caps exist, but it can happen.

I'd also go over the board with a magnifying glass to see any manufacturing defects - I assume the board was never in use?

Can you test the IIfx ROM on another Mac - fingers crossed you have a spare IIsi or SE/30 to trial?

JB

 
Byrd said:
Alright, I can just see the other battery hiding there!  I'd agree with Juror22, time to (dish)wash the board or at least clean well around the caps you've replaced with isopropyl alcohol.  You'd not expect much capacitor leakage from a IIfx as only a few axial caps exist, but it can happen.

I'd also go over the board with a magnifying glass to see any manufacturing defects - I assume the board was never in use?

Can you test the IIfx ROM on another Mac - fingers crossed you have a spare IIsi or SE/30 to trial?

JB
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the board was one of the last off the production line and never actually used in a machine, so I'm assuming this is the latest revision. I don't know how much I wanna put this thing through a vigorous wash, as much as I don't have a problem with washing boards, I was really banking on this working as smoothly as it is unused and new. I'll start cleaning all around where I did my work, but what manufacturing defects should I be looking for on this thing?

 
8 chips so no parity meaning they are not for a PC. Speed is 80ns which is fast enough for a IIfx (they made 100ns RAM for a specific printer and those are too slow). And the chips look like the sticks are 1MB each.

Amiga accelerators from GVP Inc. used 64 pin SIMMs as well which are not compatible with any other system and I don't know how to tell them apart.

I have some 1MB IIfx RAM in the basement will go find them tomorrow and take a pic.

 
Unknown_K said:
8 chips so no parity meaning they are not for a PC. Speed is 80ns which is fast enough for a IIfx (they made 100ns RAM for a specific printer and those are too slow). And the chips look like the sticks are 1MB each.

Amiga accelerators from GVP Inc. used 64 pin SIMMs as well which are not compatible with any other system and I don't know how to tell them apart.

I have some 1MB IIfx RAM in the basement will go find them tomorrow and take a pic.
Click to expand...
oof, that's a relief, I almost bought some of that accelerator ram to stick in this machine to try

 
image.pngslightly off topic, here's the whole system. once the machine is actually working I'm going to be doing a video on it. I've been dying to get this actually running for weeks now.

 
The RAM wasn't where I figured it was so will take a day or more to look for it (I did find some old VRAM I was looking for).

 
Well you should get death chimes with no ram installed at all, so pull it all and see if that gets you anywhere?

You can try exercising the reset and interrupt switches a bunch of times.   I once had a stuck one, took 3 days of troubleshooting and a bunch of voltage readings to find that problem.  Now I make sure to hit those up before anything else!

What is worrisome is the floppy drives firing off like crazy.  That doesn't sound  too good. :/

My original 1MB SIMMs look pretty similar to what you have posted, except everything is flipped 180deg.  I suppose different SIMM designs exists rather than a standard single design.  Try looking up the datasheets on the chips and compare that they are functionally the same.

IIfx-1MB.jpg

 
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