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UMAX SuperMac C series CacheDoubler

Fizzbinn

Well-known member
I thought I'd post some pictures of the UMAX SuperMac C series CacheDoubler card I got off eBay not too long ago, there doesn't seem to be many pictures out there. The CacheDoubler has 1MB of "inline" cache running at 80Mhz, double the logic board bus speed that L2 cache installed there runs at. Some interesting history on this at SuperMac Insider.

Mine's not working in my C500/180 but taking a closer look I'm pretty certain a capacitor has been knocked off... If anyone else has one of these I'd appreciate it if you could confirm it has a capacitor installed at C1 and the C&V values of the cap.

IMG_1859.jpg
IMG_1860.jpg

The CPU clock jumper block is a bit confusing to me, I think "0" means jumper in place but when I received it there was only a jumper on J4 which doesn't match up with the CPU options in the key/the 240Mhz CPU that came with it. I have J3,J4,J7 jumpered in here (the one on J3 has an open top):
IMG_1861.jpg

The way it fits in the case is kinda neat, there is a little hole that accommodates one end of the logic board L2 cache connector that would otherwise block the install. Some before and after pictures below.

With the original 180Mhz CPU and 256k L2 cache card:
IMG_1854.jpg

Now with CPU and cache removed:
IMG_1855.jpg

CacheDoubler (with 240Mhz CPU) installed:
IMG_1856.jpg

From the other side, where you can see the logic board L2 cache connector sticking through:
IMG_1858.jpg
 
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trag

Well-known member
I hope you can get it working. It looks like all the other caps on that board with that size pads are 47uF/16V.

It doesn't seem like a single missing decoupling cap would stop it from working. These things are about 20 years old. It might be time to recap the whole thing.
 

Fizzbinn

Well-known member
I hope you can get it working. It looks like all the other caps on that board with that size pads are 47uF/16V.

It doesn't seem like a single missing decoupling cap would stop it from working. These things are about 20 years old. It might be time to recap the whole thing.

Yeah... I think I am going to start with replacing all the CacheDoubler caps with tantalum 47uF/20V caps I have on hand, I see signs of leakage on at least one of the other ones (fingers crossed C1 wasn't some vastly different capacitance or voltage than the other two). I guess it could be something with the logic board caps, but it works fine with the 180MHz and 240Mhz cpu boards when they are directly installed.

Also I forgot to mention that "DARKSTAR" is a pretty kick ass printed on code name for the CacheDoubler board! Makes me think of other boards with cool printed on names... I think the 6300/100 board I have is labeled "Afterburner" :cool: I know folks like to dunk on that series but compared to the 6200/75 board it was a pretty decent improvement (600e vs. L1 cache limited original 603) but I digress...
 
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Fizzbinn

Well-known member
Sigh. Recapped the CacheDoubler but no joy, even worse I get nothing with the original CPU back in now. I guess the power supply could have given up the ghost at a crappy time, need to figure out how to test it...
 

trag

Well-known member
@Fizzbinn That's a good hypothesis. If the power supply was already struggling, adding the cache doubler might have been a little too much load. Then the failure progressed to the point where it won't support the system even without the cache doubler.

It doesn't seem like the cache doubler would add that much load, because the SRAM chips aren't all that power hungry, but I think I saw one or more CPLDs on there and they could draw some current.

Occasionally there are 100uF/6V capacitors in that physical size used by some of Apple's motherboards. I haven't seen any on the clones, but I haven't looked at the caps on every piece of clone equipment. :)
 

Fizzbinn

Well-known member
So first test has the power supply 5v trickle, as tested through the ADB port, working just fine so not sure what to look at next with the power supply other than a broad brush take-a-part and capacitor check/replacement.

In parallel I think I want to figure out a way to power via an ATX power supply. From SuperMac Insider's ATX (PC) Power Supply Conversion for S910/S900/J700/(C600) guide it looks like it should not be too hard (C500 uses same logic board as C600). Hopefully this will help me know if the issue is indeed power supply related (unless anyone has a stock working UMAX SuperMac C500 power supply they would be willing to sell!)

I'll likely start another thread on the UMAX SuperMac C500 power supply, it doesn't seem like there is much out there about it. ...one odd thing I noticed is mine does not have fan installed, hard to tell exactly but I think in the other C500 pictures that I've been able to find on system auction listings that show inside the case it looks like there is supposed to be one...

I'll pick up here once I have a workman power supply.
 

trag

Well-known member
In parallel I think I want to figure out a way to power via an ATX power supply. From SuperMac Insider's ATX (PC) Power Supply Conversion for S910/S900/J700/(C600) guide it looks like it should not be too hard (C500 uses same logic board as C600).

I wrote that article a couple of decades ago. Ignore the bit about the Mini-fit BMI connectors. They aren't compatible. But the good news is that the regular old Mini-Fit Jr. connectors are more readily available now, than they were when I wrote that article.

Also, if you need the AT style connectors, I found them at peconnector.com, https://www.peconnectors.com/power-pc-connectors/hws9498/

but it looks like Mouser has them too:

https://www.mouser.com/ProductDetail/Molex/90331-1003?qs=y2iaK3rfSTkq/9MUBWfwaw==

I think htese are the proper pins for the housings: https://www.peconnectors.com/index....ch&search_in=all&search_str=HWS1309&x=16&y=20

At Mouser: https://www.mouser.com/Search/Refine?Keyword=08500105

But that's just one of many pins that Molex says works with that housing: https://www.molex.com/molex/search/partSearch?pQuery=&sType=s&query=2478
 

Fizzbinn

Well-known member
I wrote that article a couple of decades ago. Ignore the bit about the Mini-fit BMI connectors. They aren't compatible. But the good news is that the regular old Mini-Fit Jr. connectors are more readily available now, than they were when I wrote that article.

Also, if you need the AT style connectors, I found them at peconnector.com, https://www.peconnectors.com/power-pc-connectors/hws9498/

but it looks like Mouser has them too:

https://www.mouser.com/ProductDetail/Molex/90331-1003?qs=y2iaK3rfSTkq/9MUBWfwaw==

I think htese are the proper pins for the housings: https://www.peconnectors.com/index....ch&search_in=all&search_str=HWS1309&x=16&y=20

At Mouser: https://www.mouser.com/Search/Refine?Keyword=08500105

But that's just one of many pins that Molex says works with that housing: https://www.molex.com/molex/search/partSearch?pQuery=&sType=s&query=2478
Thanks!!!
 

Franklinstein

Well-known member
Neat. I'd like to find one of those. Also some of the '040 L2 cache cards in the same style.

As for the power supply on these, on my attempt I just cracked open both the stock and a suitable ATX unit and resoldered harnesses between them: no fuss, no muss, and everything looks stock (except for the new PSU being black with a big fan on the bottom). The stock units (at least as far as I've seen on various S900s) are Seasonic so they're well worth recapping if you're into that.
 
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