Power Computing Power Base 200 Problems

[CC_333]

Hi,

I have a seemingly uncommon PowerMac clone here, and I can't get it to boot.

I had it in storage, and something made a nest inside and ruined the logic board. I accidentally came across a replacement one a couple years later, but it had a red x drawn across it, which I assume means it is broken.

And broken it is! I can get it to chime, but nothing I do will allow it to go beyond that. No video. Nothing.

I don't think it's the memory, but who knows.

The CPU card is okay, because it won't chime if I take it out.

Obviously the board I got is at least as broken as the original, but at least it's intact with minimal corrosion and remnants of nests and stuff.

I tried transplanting some of the capacitors (which are known to be at least partially functional) to see if that would help. It did not.

I was even going to go as far as swapping the soldered down, surface mount ROM chips from the other board (those are also known to be good), but I gave up on that after wasting several hours removing them from the old board.

I also speculated that perhaps the power supply is at fault. Since it's the only compatible one I have, I unfortunately can't verify that hypothesis.

Any Ideas?

If I can't get it fixed, I'll hunt around for another, hopefully working replacement logic board.

c

 

[macinbot]

I'm pretty sure that all the Power Computing line used standard ATX power supplies and pinouts. If you can find a standard PC ATX power supply it should work straight across. I had two Power CC machines (PowerTower 180, PowerBase 180) and they were fairly flakey. This is when they were only a few years old. I personally don't think that they were built for the long haul. They did have the BEST marketing of any Mac or PC of that era hands down though.

 

[coius]

PRAM battery. If it's dead, it will not output video. I used to have one of these and a dead PRAM battery prevented the video from being displayed. Also, make sure the CPU card is fully seated (despite being based off the 6400/6500 this used a CPU DaughterCard).

If it doesn't work then, try swapping out RAM modules. Most of them from the 7xxx/8xxx/9xxx series should work. i didn't put a module in mine that didn't work, even 64MB DIMMs. However, 128 will NOT work as those capped. I think that has 3 RAM slots right?

Also, make sure that secondary Riser with the PCI slots is fully seated. That contains the video card for that system. If that doesn't seat, no video.

 

[CC_333]

I'm pretty sure that all the Power Computing line used standard ATX power supplies and pinouts.

I'll give that a try.

I had two Power CC machines (PowerTower 180, PowerBase 180) and they were fairly flakey. This is when they were only a few years old. I personally don't think that they were built for the long haul.

I guess not, but it worked fine and was fairly stable before the nest invaded.

PRAM battery. If it's dead, it will not output video.

It worked fine from the day I got it with a dead PRAM battery. Maybe I'll try that.

If it doesn't work then, try swapping out RAM modules.

I'll try that.

Most of them from the 7xxx/8xxx/9xxx series should work.

Good! I have a 7500 which should work.

Also, make sure that secondary Riser with the PCI slots is fully seated. That contains the video card for that system.

I know. I'm fairly sure it's seated (I even tried spraying contact cleaner/lubricant in the connector to make sure it was a good connection).
I will post back with my results.

c

 

[CC_333]

Hi,

So far, I've tried a PRAM battery and seating the PCI riser firmly. No change in status was noticed.

Next, I have to try a new power supply (I may borrow one from another computer), and swapping RAM.

This model has no built in RAM, does it? Perhaps that may be causing problems somehow. Wouldn't I hear the death chime, though?

I'm afraid I may have to declare it dead if the power supply and/or RAM doesn't fix it.

In the event that happens, I'm going to have trouble finding parts for it.

c

 

[coius]

how about the CPU? Original or was it upgraded. The daughter card can't be from the Mach V machines as those will not work (such as the late 9600). The CPU itself could be causing your issue and I assume your reseated it as well. and you made sure it was all the way down?

Also put a PCI Video card in it. your onboard video could've died. It's rare, but it can happen.

So you could take the 7500 CPU daughtercard and throw it in, and then if you have a PCI video card throw that in. if it's got a G3 upgrade, make sure the settings around right for the CPU. Also keep in mind that if the CPU expects a certain bus speed, and it doesn't match the PowerBase, the powerbase may not work or start. Especially if the timing is messed up, It may barely sync enough to cause the chime, but get unstable immediately after. You never know.

 

[CC_333]

how about the CPU? Original or was it upgraded.

It's original-- PPC 601 at 200 MHz.

Also put a PCI Video card in it. your onboard video could've died. It's rare, but it can happen.

I tried that by using a PCI card from a beige G3. No change.

So you could take the 7500 CPU daughtercard and throw it in,

I tried that, too. It didn't work.

if it's got a G3 upgrade' date=' make sure the settings around right for the CPU.[/quote']G3s have nothing to do with this machine, except that the video card I tried happened to be from a G3 Power Mac.
I'm getting a bit frustrated by this machine. Nothing I do seems to fix it.

I just tried a known working ATX power supply, and it behaves the same way as before: chime, and then nothing. About the only thing the new P/S did was make the machine quieter!

Also, I examined the board near the memory slots, and found a row of small-ish chips where I'd imagine a fourth memory slot would've gone. That must mean that there is some built in memory, which explains why it still chimes when all the slots are empty.

I think I need a new logic board (or some component lever repairs dome on the current one). I highly doubt the CPU card is at fault.

Either that, or maybe I could just sell it and be rid of it? Opinions??

c

 

[coius]

Just out of curiosity, are you using a VGA monitor through an adapter on the machine? or an apple DB-15 monitor on DB-15 port? If using an adapter, change the adapter or use an apple monitor that doesn't require an adapter.

 

[CC_333]

Hi,

I'm using a known good Apple HiRes RGB monitor via the DB-15 port. I have also tried various VGA CRTs and LCDs (using the VGA port; no adapters) with no luck.

Having tried all of the suggestions mentioned in this post with no results, I think there's something wrong with the logic board, and it'll have to be either repaired or replaced.

Until then, I fear it's like repeatedly beating one's head against a proverbial brick wall.

I welcome any and all other suggestions besides those already mentioned.

c

 

[trag]

Apple CPU cards will not work in the PowerBase. The PowerBase chip set requires a couple of CPU signals which aren't present on the Apple CPU card connector.

It's hit or miss whether third party upgrades will work in the PowerBase. It depends on whether the upgrade is late enough (new enough) to have implemented the signals that the PowerBase requires.

That will not solve your immediate problem, but it will save you from wasting time on CPU cards which can't work in the PowerBase.

I would check the 3.3V power on the logic board. I had a logic board once which had a similar problem. It turned out that there was an internal short in one chip between the 5V and the 3.3V supplies and the clock buffer to the PCI bus runs off of the 3.3V supply. No PCI bus clock, no PCI devices. No PCI devices, no video. So, good chime. No video -- or other PCI dependent activity.

I found the shorted chip, once I knew what to look for, because it was very hot. But it could also be an internally shorted capacitor, or similar. Take an ohmmeter to a powered-down board between 3.3V and Ground. It should be, IIRC around 500 ohms. Check the resistance between 5V and 3.3V and 12V also. I don't remember what's typical there, but the values are kind of an average of all the leakage across the chips, so take some measurements on some known good board -- like a 7500 or similar and compare. The ballpark should be about the same.

 

[CC_333]

OK, I'll do that.

If I find that some chip is at fault, how do I repair/replace it?

In the event that repairs are necessary, is there somebody on this forum who would be willing to do them for me for a fee?

c

 

[CC_333]

OK, I'm digging my thread up from the dead to close it up (it's been so long, I forgot this was here!). I know this isn't good practice, but it's my thread???

Anyway, in the ensuing 7 years since I originally posted this thread, the PowerBase has basically sat on a shelf, collecting dust, and waiting for me to figure out what to make of it. Hack in a PC motherboard? Find a replacement stock motherboard??

So, here we are in 2019, and I decided the other day on a whim to search for Power Computing-related stuff on eBay, as I have off and on this whole time. Lo and behold, I see a logic board from a PowerBase at a good price. I couldn't buy it fast enough, because I probably will never see one like that again!

I had some downtime today, so I installed it, and I've *finally* confirmed that the logic board was indeed the problem! I can also confirm that both the power supply and PCI riser (and thus the graphics subsystem) are in fact working fine. I should test the CPU card, but since the new-to-me logic board also came with a CPU card which is 40 MHz faster, there isn't much of a point other than to pinpoint the cause of the original failure. Be that as it may, it's all academic now that I finally have everything working.

So a very belated thank you to all who helped me out here. It's nice to finally bring closure to this long neglected project.

c

 

[trag]

Glad to read you got it working.   I was looking through the thread to see if your original board had the original CPU card, and you said it did, up there somewhere, but you also wrote that it was a 200 MHz 601 card.   I hope you meant 603...

 

[CC_333]

I saw that, and I'm pretty sure I was in error, because it's definitely a 603.

c

 

[CC_333]

OK, so new problem.

It boots and everything, but ADB is 100% dead. It worked yesterday?

What happened?

c

 

[CC_333]

I feel like a total dunce! :scrambled:

I was looking at the old, thought to be defective logic board I recently bought a replacement for tonight, and decided I'd try it out, but with the RAM and L2 cache from the new logic board. I figured since it was dead anyway, I didn't have much to lose. But I had a hunch that maaayybe it would work with the new RAM, L2 or CPU.

So, I took the thing and, first, put the original 200 MHz CPU card in the new board, to check that it works. It did! OK, so that eliminates that variable....

Then, I took the "old" logic board and put it in. I then swapped over the RAM and L2, plugged in the 240 MHz CPU card (because why not?), and.... lo and behold, my hunch was right! IT WORKS!! And it even has fully functional ADB (and PS/2)!

For TEN YEARS I thought it was the logic board that was bad, when it turns out it was actually bad RAM and/or L2 all this time!

At least I got an upgraded CPU out of the deal!

Sheesh!

c

 

[Compgeke]

I'm not terribly surprised. I have a PowerComputing something or another 200e here that also had bad L2 when I got it. In my case, I wouldn't even get a bong though, just turn it on and nothing. Ultimately ended up just throwing a spare G3 upgrade I had in it and it's been going ever since. 

Wonder if it's just coincidence or if maybe there's a defective thing with some of the L2s PowerComputing used. 

 

[CC_333]

Maybe. We may never know though, because I've long since misplaced the original L2 module. If I ever do find it, perhaps I should test it?

Actually, will it work without the L2?

Anyway, I have another odd issue (this showed up on the other board too): only two of the three RAM slots seem to be registering in System Profiler. Instead, there's two slots with 32 MB each, plus one that says "builtin," which reports having 8 MB. If that were all, I'd just figure I have a dead RAM module or something, but the total installed RAM is 96 MB?! 32+32+8 ≠ 96!

Any ideas as to why this is so?

c

 

[Compgeke]

It’ll work fine without the L2, it’ll just be quite sluggish. Think like a PowerBook 1400/117 if you’ve ever used one of those. No idea on the ram.