IIfx resurrection

[PacificState]

I recently purchased a Mac II that had been upgraded to a IIfx - it has the original case but an upgraded motherboard, and both an 800K and 1.44MB drive - and have been trying to get it running again:

- Firstly, I installed new batteries and turned it on to get a chime

- However, I was using a 15 pin -> VGA adapter -> cheap HDMI converter and was unable to get any recognized signal

- The power supply then blew up about 5 minutes later; as might be expected, the RIFA cap has split in two

Based on that, I'm going to recap the PSU / replace the fan (based on https://longview.be/macintosh-iifx-astec-power-supply.html), and recap the surface mount electrolytics on the motherboard - but was wondering if there's a good way to connect a IIfx to a HDMI monitor? It appears to have both a 820-0198-A7 Mac II video card, and two other cards I can't identify (pictures below if you can help!). Thanks in advance!

 

[finkmac]

with regards to the fan, that post you linked.. their power supply says "699-0389"... that's a II/IIx power supply. not variable speed, and rather loud.
check your power supply. IIfx should be 699-0393. in my experience, it runs fairly quiet.

the two mystery cards appear to be a video card of some sort, and an ethernet card.

 

[PacificState]

Thanks! Unfortunately, mine is indeed the 699-0389 - presumably as it started life as a II. I'm not sure if there's a particular benefit other than the fan?

Otherwise, I appreciate the pointer to the card. I do have an OSSC and BMOW sync adapter, so I might try those next once the PSU is repaired.

 

[ClassicGuyPhilly]

Good luck, always need to cheer on another IIfx on its way back to life!

 

[PacificState]

So the power supply is now recapped, with a new RIFA and fan. Few things for reference:

- The cap listing in the link I posted above seems slightly off; you can actually buy a new pack of caps for this PSU Console5 (https://console5.com/store/macintosh-ii-power-supply-cap-kit-astec-aa13780-699-0389.html / https://wiki.console5.com/wiki/Macintosh_II).

- I had forgotten where all the star nuts went; it turns out they're used to secure the power supply board to the case where the holes have metal rings.

- I used a Noctua fan, which a.) doesn't match the M3 case mounting, and b.) uses a three pin connector. For the first issue, I used M3 press nuts that I inserted with a soldering iron (which I had to hand as I've used them in 3D prints), and for the second I crimped on a KK254 header (Molex 0022013027) to one of the adapter cables that came with the fan.

 

[chrisrueckert]

@PacificState great write-up, thanks! I'm going through the same process right now. Regarding the fan: I noticed only 5V on the PSU plugs for the fan, though on your picture, I saw your new fan is a 12V fan. Does it actually work?

 

[PacificState]

I was definitely confused when I put it all back - there’s 5V on the main board which is used to power the LED (even though IIRC this is labeled as for the fan!), and ~9V on the ‘riser’ board which is actually the fan connector (I’m not sure this is the expected voltage, but it’s what I got after the recap - I didn’t dig more). If you’ve kept the original fan, it should also be marked as 12V, for confirmation.

I’m about to replace the motherboard caps, including C1 - note that you should apparently change this as it otherwise fails with a bang.

 

[willmurray461]

If your motherboard has a tantalum installed at C1, I'd replace it with an electrolytic part. Either that or use a 25V rated tantalum.

C1 is attached to the 12V line, and it's often advised to de-rate tantalum capacitors by 50% of their rated voltage. Running them close to their rated voltage degrades their lifespan, which can lead to shorts that cause fires and (small) explosions. C1, like the rest of the caps, is a 16V part, hence why it fails frequently. IIRC, the other caps all connect to 5V, so 16V parts should be fine.

 

[PacificState]

Thanks; I actually went like-for-like and swapped in a 25V tantalum at C1 and two 25V electrolytics elsewhere. I still can't figure out why the mix of capacitor types was chosen, though!

 

[PacificState]

So, it works! I was able to boot to Finder with a few caveats:

- The motherboard and PSU are missing the screws. From https://68kmla.org/bb/index.php?thr...screw-size-repairs-1989-memory-and-box.46770/, these are part number 426-3401, and replacements with captive lock washers seem hard to find. If anyone can recommend a source, please let me know!

- I'm connecting the IIfx to my Dell HDMI monitor through an OSSC and a Mac Sync-inator (https://www.bigmessowires.com/mac-sync-inator/); I can only get (fairly poor quality) output from one of the cards (where the refresh rate is 35kHz), and no output / out of range from the other (with a 58.14kHz refresh rate). I'm more familiar with 15kHz support for Amigas - can anyone recommend an LCD that might support these cards properly?

 

[Callan]

Haven't seen any with washers, but with a little blue loctite these should work :

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

Another great place to look for hardware is Boltdepot.com, but they don't seen to have any m3.5 screws unfortunately.

Bah... just noticed he linked mcmaster-carr in the other thread. Sorry!

 

[Byrd]

I'm connecting the IIfx to my Dell HDMI monitor through an OSSC and a Mac Sync-inator (https://www.bigmessowires.com/mac-sync-inator/); I can only get (fairly poor quality) output from one of the cards (where the refresh rate is 35kHz), and no output / out of range from the other (with a 58.14kHz refresh rate). I'm more familiar with 15kHz support for Amigas - can anyone recommend an LCD that might support these cards properly?

It's a bit of a gamble but maybe try to look out for a LCD that's happy outputting 15kHz with the assumption that it might work with a higher range of oddball refresh rates like yours, see link below. Alternately if this IIfx is a keeper the Apple 13" Trinitron is what you want and it's quite square and easy to store.

List of modern monitors that support 15 kHz analog RGB signals - 15 kHz RGB Video

15khz.wikidot.com

 

[chrisrueckert]

The power plug on my riser board does not drive the original nor a new replacement fan with 12V anymore. Is this power source controlled by a temperature regulator that only enables voltage upon reaching a certain temperature limit?

 

[PacificState]

If it’s the original II power supply, it has no temperature control. What voltage do you get when you measure?

 

[chrisrueckert]

I measured 10V. After checking the plug to the fan again I noticed it would not sit properly on the pins. After crimping a new one, the fan is now working. Thanks for all the help here!

 

[q700fan]

It's a bit of a gamble but maybe try to look out for a LCD that's happy outputting 15kHz with the assumption that it might work with a higher range of oddball refresh rates like yours, see link below. Alternately if this IIfx is a keeper the Apple 13" Trinitron is what you want and it's quite square and easy to store.

List of modern monitors that support 15 kHz analog RGB signals - 15 kHz RGB Video

15khz.wikidot.com

The AOC 27b2h supports old Mac video input great. And 15khz too (even though the manual claims it doesn’t).