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The quest to revive a Umax Pulsar S900 (image thread)

CircuitBored

Well-known member
Let's do this all over again! This is the combined edition of my two previous posts about my Umax Pulsar (AKA Umax SuperMac S900) revival project, which were both lost in "the event".

I picked up the Pulsar (left) along with some other machines/ goodies from @joshc just last month. It was in a pretty sorry state, missing its front door and not showing any video when powered up.

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I set about gutting it and inspecting it for obvious troublemakers. Nothing jumped out at me immediately besides the fact that this thing was absolutely filthy in a way I've never seen before. It was coated with a strange black residue that turned to goop and smelled awful when I wet it. Here's a sample of the general before/after cleaning of this machine.

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The CPU heatsink was extremely clogged up and appeared to have been home to some sort of insect at some point. It responded very well to a scrubbing with warm soapy water.

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After scrubbing the whole machine to within an inch of its life I put it back together. I hit the power button and hoped for the best. Still nothing. The Pulsar was chiming but still not showing video. Deciding that the video card was likely causing trouble I removed it and gave it a cleaning. It's the original IxMicro Twin Turbo 128M.

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I slapped it back in the Umax and gave it another try. Still nothing. Then I remembered that the video card has a socketed ROM so I pulled it and took a look. It had the blackest pins I've ever seen. I spent about an hour scrubbing each pin with extreme care as they are extremely fragile. I accidentally bent one by dropping the chip half an inch onto my desk. After I put it all back together, crossed my fingers, hit the power button and...
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It lives! It booted an OS 9 install disc very happily. Sadly the installer could not see the hard drive so I began the dreaded task of futzing with SCSI jumper settings. After a few hours nothing was working so I resorted to cleaning the HDD's control board. What do you know? It worked! After installing OS9 I noticed that only 64MB of the installed 256MB was being recognised. The machine was still being flaky at times so I thought "surely the RAM doesn't need cleaning too?" I was incorrect. I scrubbed the DIMMs and, lo and behold:

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256MB of wonderful (and frustratingly rare) fast-paged DRAM. Oddly this machine was being recognised as a Power Macintosh 8500, which as far as I'm aware is not quite correct. Reinstalling OS 9.1 instead of 9.0 fixed this minor issue.

I wanted to install the original Umax version of OS 8 on this machine but it simply would not boot the install CD, which I successfully tested in two other Macs. I have since established that anything pre-OS 9 simply will not work on this system. Weird. Installing OS 8 from an external drive "worked" but threw up a "this disk is not for this Mac" error on first boot.

Beside this odd flaw the Pulsar runs really well once it's booted. There are a few gremlins: it often won't chime on first press of the power button, sometimes (1/20 boots) the ethernet port doesn't work until a reboot. Beside this the system runs stable as a table once booted.

I was somewhat unhappy with the condition of the case. Originally I had planned to design and 3D print a new front door but I quickly realised just how frustrating this was going to be without actually having access to the aforementioned door. I optimistically decided it would be prudent to track down an S900 with a case in nice shape but dead internals. Right, because Macintosh clones are a dime a dozen...

Then something strange happened. While browsing FromJapan I stumbled upon a listing for... a Umax Pulsar in great shape!

...with a PowerMac G4 inside it. Weird.

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The somewhat bent-looking logic board set off some alarm bells in my head but the PCI Firewire/USB card plus a GeForce 3 Ti sealed the deal. Sadly the hinge on the door was broken but I figured it was better to have a damaged one than no door at all. I bid on it, won it, and began the tense waiting game while it made its way over from Japan. Postage was not cheap.

It somehow made it to the UK in one piece. Look at that lovely door flapping in the wind.

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Here are the complete units side by side. Note that the EU-spec Pulsar's script reads Umax UmaxPulsar whereas the Japanese version simply reads Umax Pulsar.

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At this point I noticed a rather lovely inscription on the inside of the door. The previous owner was good enough to tape the broken hinge piece to the back of the door - ace!

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Then I removed the side panel and the smile on my face was replaced with an expression that words cannot describe. Here's a side-by-side of my stock Pulsar and the freakish Pulsar-G4. I recommend viewing the second image full-size so you can properly soak in the insanity.

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Loose wires, cable adapters, general chaos reigns.

I removed the expansion cards and the logic board fell out. I guess those were load-bearing cards.

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I tested the board in a nearby G4 and it does not work. Shocker.

At least the front panel had some more goodness in it. There's a very nice DVD recorder and a UHD floppy drive, which is extremely rare. The blanking plates from the front panel were a good get too.

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Another structural marvel: a PCI slot cover holding up... something?


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The logic board had been fixed in place with double-sided tape. There were some screws in there but they appeared to have been used as spacers rather than mounting hardware.

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After recovering from the shock of this disastrous case mod I set about moving the lovely new body panels onto my scruffy original Pulsar.

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She's looking fantastic! I was even able to get the USB/FireWire card working, although I have been warned that this may cause conflicts with further PCI additions down the road. Did I mention that the package from Japan also included a NIB keyboard and mouse? I guess these ADB peripherals never found much use on the USB-only G4. The keyboard is Japanese-spec, which actually fits in quite nicely with certain trends over in mechanical keyboard land. It's a rather nice rubber-dome board but if only it were mechanical...

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So what's next?

Well, it's starting to seem like this machine needs a recapping. It works really well once it's warmed up but only once it has warmed up. Beside that, this is a great old runner with a very interesting provenance. I recommend reading about the history of the Supermac and Umax, it is a great story. Here's a link to a great site with all you need to know about Umax.

I have a Sonnet G3 upgrade on the way, having sourced one extremely quickly thanks to the venerable @Bolle. I'm on the hunt for some more DRAM but, as mentioned above, it is extremely hard to find 64 and 128MB DIMMs for these machines nowadays. If you have a line on some then please let me know! I'm tempted to upgrade the video card to something with 3D acceleration but I just love the name Twin Turbo and would struggle to part ways with it. I have a PCI SATA host in the works but I really need an IDE host so I can hook up the DVD and UHD-floppy drives.

All in I would call parts one and two of this endeavour a resounding success. I have a working example of a fantastic and extremely rare machine and it is soon to be full of all sorts of exciting upgrades. It'll be taking up a whole episode of its own when I finally reboot my YouTube channel.

I hope you enjoyed my account of this adventure! Please do comment with your thoughts or any handy S900 trivia you might know.

All the best and welcome back to 68KMLA,

P
 
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CircuitBored

Well-known member
It appears that something strange has happened with the images on this thread. I am looking into fixing this!

edit: fixed!
 
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joshc

Well-known member
As I think I said in the last thread, I'm so glad you were able to breathe new life into this machine. I didn't have the time to dedicate to it, so it's great to see it running again. I do think the mid 90s Macs are teetering on the edge of what needs a recap - when I couldn't get it working, I wondered if the caps may be at fault. Might I also suggest double checking the voltages from the PSU are good? Anything awry there won't help.
 

CircuitBored

Well-known member
Benchmarks! Here are the results from MacBench and Speedometer respectively.

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A mere 650 times the power of a Quadra 601... I am honestly amazed that this hard disk made it through the test and even got a good score. It sounds worse every time I boot the computer.
 

trag

Well-known member
I've had a couple of S900 boards turn flakey on me. I looked at recapping one, once. There are a lot of 47uF caps on that board. Vastly more than on a Mac II series machine.

In my case the machines eventually would not boot. I thought it might be a problem with the CPU slot as I had the MB in a PC case and there was no support for the top edge of the CPU card and it seemed like removing and reseating the CPU card helped the problem, some times.

One of these days I need to try recapping one and see if that brings it back to life. I hope so because there is no source for the CPU slot connectors.
 

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iJol

New member
Hello together,

I've got two Umax S900 a few weeks ago, one with a faulty power supply. Tried to it, but it still doesn't power on.
I've found a website with ATX conversion for the Umax S900, but the new ATX style PSU's don't have the -5v rail and there are no adapters with the third P10-connector available.

Does the S900 need the -5v rail?

May anybody can help.

Regards,
Julian
 

trag

Well-known member
Here's an article on creating -5V from the -12V line. Basically, implement a 7905 voltage regulator with the -12V line as source.

If would be interesting to try the ATX conversion and just leave out the -5V line and see what happens or doesn't work. I can't figure out what needs it. Serial ports maybe?

 

iJol

New member
Here's an article on creating -5V from the -12V line. Basically, implement a 7905 voltage regulator with the -12V line as source.

If would be interesting to try the ATX conversion and just leave out the -5V line and see what happens or doesn't work. I can't figure out what needs it. Serial ports maybe?

SCSI doesn't work properly, I've tried it. I get a Happy Mac but it's not going any further. I get the chime and the screen comes up and then it sticks on the Happy Mac.

I can't use the power button on the Umax, I have to touch the Ground- and the Power On-Cable to get the computer started. Don't know, if I did something wrong by crimping the cables or my PSU is crap (just a cheap ATX PSU from Amazon)
 
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iJol

New member
Here's an article with the pinouts for the S900 and the old ATX pinout. You might double check that you got the ground and the 5V standby in the right place on the S900's 3 pin connector.

http://www.kennedybrandt.com/supermac_insider/support/psconversion.html
That's the pinout I've used, but my S900 has a slightly different pinout - my J26 connector don't have a purple wire, just a red one for example. I think I try to get an old-style ATX PSU on eBay and try it with it, because I've used a modern one.
 
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CircuitBored

Well-known member
I got a CPU upgrade! It's a 400MHz Sonnet G3 courtesy of @Bolle

Here are some benchmarks:

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You might notice that the disk speeds are now even more ridiculous than the CPU speeds. That's courtesy of the PCI SATA card and SSD now inside! I am finally free of the horrendous noise made by the original hard drive.

I'm still toying with upgrading the video card but the only thing left which really "needs" to be done is replacing the slightly noisy PSU fan. This "Mac" is now quite something to behold!

I am still on the hunt for an IDE host card - let me know if you have one!
 

trag

Well-known member
That's the pinout I've used, but my S900 has a slightly different pinout - my J26 connector don't have a purple wire, just a red one for example.

The wires' position on the connectors is what matters. Not the wire colors.
 

trag

Well-known member
I got a CPU upgrade! It's a 400MHz Sonnet G3 courtesy of @Bolle

Here are some benchmarks:

I'm still toying with upgrading the video card but the only thing left which really "needs" to be done is replacing the slightly noisy PSU fan. This "Mac" is now quite something to behold!

I am still on the hunt for an IDE host card - let me know if you have one!

Nice testing on the G4 upgrade.

I'm going to put some Converted Radeon 7000 up for sale one of these days. I replaced the serial Flash chip with the full 1Mbit chip so they should work just like the Macintosh version. I'm not quite sure what to ask for them though. I'm leaning into the neighborhood of $50 + shipping.

I have 40 Acard 6280's in the attic. One of these days I need to convert them into the M version. Sigh. Still can't find a flat workspace. Only converted the R7000s because I was able to use the soldering station in the lab at work.
 

CircuitBored

Well-known member
I'm going to put some Converted Radeon 7000 up for sale one of these days. I replaced the serial Flash chip with the full 1Mbit chip so they should work just like the Macintosh version. I'm not quite sure what to ask for them though. I'm leaning into the neighborhood of $50 + shipping.

I have 40 Acard 6280's in the attic. One of these days I need to convert them into the M version. Sigh. Still can't find a flat workspace. Only converted the R7000s because I was able to use the soldering station in the lab at work.

The CPU upgrade was definitely worth it! The Pulsar boots first try a lot more reliably now.

Wow! Forty Acards!! I'd definitely take two of those and a Radeon 7000 if you ever get round to putting them up for sale but I'm in the UK so shipping might be problematic...
 
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