Stupid powermacintosh 7600s

[matthewgeek123]

Hi
I am new to this mac thing and need some help.
I have a powermacintosh 7600/120 (120mhz) which I got given without a keyboard, although with a mouse. When I try to start it I hear the fan and hard disk start and the LED goes but nothing comes up on the screen and I cannot hear a startup chime. Do I need a keyboard to start properly? If it doesn't have a keyboard does it decide that it's running headless and not show picture?

I have replaced the PRAM battery (with a couple of button cells) but that makes no difference. I also pressed the CUDA reset button and that also did nothing, although I might have done it wrong.

Any help appreciated,
Matthew

 

[Hrududu]

You don't need a keyboard to boot up. Check your RAM and the video memory. You might also verify the processor is seated properly.

 

[DeltaMac]

Check the voltage from your PRAM battery. The original is 3.6 volts, and some old PowerMacs might not boot properly if the voltage is less than 3.2. Your pair of button batteries may not be providing that much.

Try reseating the RAM. Put RAM back in the slots one at a time, then try a boot after inserting each card.
You should also try reseating the processor card.
You can reset the logic board by removing all power, along with removing the PRAM battery. Unplug the power supply connector from the logic board. Press and release the power button, then wait at least 10 minutes before reinstalling the battery. Connect to power, then try to boot.
That logic board reset will reset the PRAM, so you won't need the keyboard to do that reset.
You should look for an ADB keyboard that you can use, as you won't get much use out of it without a working keyboard. However, it SHOULD still boot with video without a keyboard, but what will you do with it then?

 

[bunnspecial]

These can be funny about RAM. I have no experience with the 7600(although I do have a 7350, which is more or less the same thing, although I've yet to boot it) but have been playing a lot recently with some other x600 series Macs.

You will notice that you have RAM slots labeled A1, A2, A3, and A4 along with corresponding slots labeled B1-4. These computers are designed to "interleave" memory between like numbered slots in the A and B banks. If the memory is completely mismatches(i.e. one is a 32mb and one a 64mb) it will not attempt this. If, however, the RAM is "close" the computer may try to interleave but may not be successful. This can cause problems.

I'd suggest starting by pulling all the RAM out of one ban-either A or B. If it still won't boot, take it down to one stick, and even try that one stick in several slots. If this gets it to boot, you can then start(carefully) rebuilding the RAM. I recommend sorting by manufacturer, capacity, and timing and only putting sticks that mach in all of these aspects together for interleaving. If you can't do that, purposely re-install the RAM to avoid interleaving. Fill up bank A, then put chips of a different capacity than their partner slots in B.

I'll also mention that if it doesn't chime, it probably wouldn't hurt to make sure the speaker is actually connected . This has caught me a few times. If you are attempting to use an LCD monitor or other VGA monitor via one of the dongles, be sure the switches are set correctly. If you installed a video card with VGA out(something I often to so that I can avoid dongles) make sure it's seated firmly-you may need to pull it out and reseat it a few times to help clear corrosion, or may just move it to another slot. I find it can take a couple of variables out when trouble shooting if I an Apple CRT with the correct DB-15 connector on it.

 

[matthewgeek123]

Display adapters

Hi
Thanks for the thoughts.
I decided that I should probably start with simple first and look at my DB15 to vga adapter. I found a black version of it on the internet which implied that it was for DB15 moniters and vga computers. Here are some photos:
https://www.dropbox.com/s/pe6pieluyjm1mhr/IMG_1341.JPG
https://www.dropbox.com/s/sxnatmlhrepkcy4/IMG_1344.JPG

There are no switches or other text on it.
Are these the correct adapters?, if not I need some tips on what ones to get.


I also made sure the speaker was in (it was) and tried some external speakers but still couldn't hear a ding of any sort.

EDIT:
I have got a video card in there, would that distract the onboard ports? It still gives me a black screen when using the card.

Another edit:
It looks like one bank of memory has 5 slots and the other one has 3. There is also a different slot between the two rows. EDIT: NOPE - noob mistake; I can now read text on a circuit board. But still, what are those other slots? There's a couple more behind the ram banks.

Thanks,
Matthew

 

[DeltaMac]

The one offset slot is for a cache DIMM. That might not have anything in it. Two banks of 4 RAM slots - look at the markings on the logic board again. The odd cache slot is certainly in a strange position.
4 slots by themselves are the VRAM slots. They need SOMETHING in the slots, and might only have two cards in place.
One more slot, parallel to the RAM slots, but on the far end, is the ROM chip. Depending on model, it could be removable, or might be soldered to the logic board. If removable, reset that card, too.
Try removing any PCI cards.
The adapter that you have MIGHT not work on modern VGA monitors. It was sold for use with Apple's 21-inch display, and you may be missing a signal (sync-on-green, IIRC?) with newer VGA displays, and the adapter is ONLY useful with the single-resolution displays, and will not work on any other display except that 21-inch Apple display. I suggest that you look for the ones with DIP switches, or selector knobs, which are much more likely to work.

 

[bunnspecial]

Here's a diagram of the logic board from the service manual.

Only remove sticks in the slots marked as above. You can remove and reseat the VRAM, Cache, and ROM, but don't leave them out.

And, again, you might see if you can pick up an Apple-branded CRT with a DB-15 connector locally. They tend to be cheap as they will really only work with old Macintoshes, and can take out a lot of variables when troubleshooting. If you want to use a VGA monitor(let's face it, most people would rather use a flat panel these days) and have PCI slots-which you do-the best solution is to find a Macintosh PCI video card. The Rage 128 should be cheap($10-15 on Ebay). Even though we often joke about these cards on here, they many times better than the built-in video and really are fine for OS 9 and earlier. They can pretty comfortably drive a 1280x1024 display at millions of colors-something not possible with the on-board video.

 

[matthewgeek123]

Hi
Thanks for all the answers
I just want to check, will it run (and beep) without a screen? I just looked a the video card and it's fan wasn't spinning which can't be a good sign. I have no idea about my adaptor and am going to ask the person who gave me the mac if they have the screen.
I had a quick look at my ram. Here is what I found:

Bank A
1.64mb - ram direct.
2.16mb - ?
3.? - paccom
4.64mb - nanya written on chips.

Bank B
1.64mb - ram direct
2.16mb - ?
3.? - paccom
4.64mb - nanya written on chips

Thanks for any answers
Matthew

 

[bunnspecial]

You should get a chime even with no display connected.

I'm not sure about what you mean by the "fan on the video card." These don't have a discreet video card normally(unless one has been added) and unless it's a flashed PC card none of the cards that will work in this system have a fan. The only fan I'm aware of offhand is the one in the power supply. I don't know if these have a second fan right over the RAM like the G3 desktops, and can't go and check my 7350 now. If you have a PCI video card installed, take it out(to eliminate as many variables as possible) and use the onboard video.

In any case, your RAM pairing looks correct. Even so, a single bad stick can keep it from booting. I managed to kill a stick of PC-133 the other day with an inconvenient spark from the logic board(loose cap) and the computer refused to boot with that particular stick installed. In that case, the computer gave 3 beeps. I've seen similar things happen many times in many different Macs. I've had many that would do nothing(not even give an error beep) when a perfectly serviceable RAM stick that the computer just didn't like was installed.

I'd still start with the RAM. Again, remove all but one stick and try to boot off it. Try it in multiple slots. If still don't get anywhere, try a different stick(you may have inadvertently grabbed the bad one on your first try). You have 8 sticks that are nearing 20 years old, and Macs can be so funny about RAM that it's worth eliminating as many variables as possible-hence my suggestion to use only one stick.

 

[matthewgeek123]

Video card

Yes, a video card had been added, the sticker says ATI rage theater.

Matthew

 

[bunnspecial]

Yes, a video card had been added, the sticker says ATI rage theater.

Matthew

As a first step, I'd(again) recommend removing it and trying to boot again

As far as I know, that particular card was only made in a PC version, and I don't know if they can even be flashed to be Mac compatible.

 

[matthewgeek123]

Hi
I have just removed the video card and tried rebooting, again no difference:\

Matthew

 

[DeltaMac]

Fans in video cards tend to pack in dust, etc. You can try to turn the fan by hand, to see if it even moves. Blow it clear, if you think it is worth doing.

 

[Ih8reno]

I have a Rage Theatre card in my B&W, got it used so I don't know if it was flashed or not but it is compatible.

 

[Hrududu]

Remove the cache DIMM. I have a feeling that may be your villain right there.

 

[matthewgeek123]

Hi
Thanks for all the answers, they really helped.

I reseated the CPU card and tested the speaker and now I get a startup chime. I have pulled the RAM out and tried reinstalling one at a time etc but got no further.

The cache dimm is either very stuck or has a locking mechanism I am overlooking but I cannot get it out. Is there a trick to removing it?

I also noticed that the rom simm is empty and I am thinking that it might be the problem. Should there always be a rom simm there?

I also think I don't have the original apple CPU card, instead one branded "newer tech". Will this effect much?

Thanks,
Matthew

 

[keysersoze]

I've got a couple extra 7600 logic boards sitting around doing nothing-- if you decide that the mobo is the issue and you want another just PM me.

 

[bunnspecial]

Hi
I also think I don't have the original apple CPU card, instead one branded "newer tech". Will this effect much?

Thanks,
Matthew

NewerTech processors have a very good reputation. As long as there aren't any problems with the card, you should be okay.

With that said, it would be good if had an OEM Apple CPU card to install just to eliminate all variables. Do you have any other x600 era machines that you can borrow a CPU from?

One other thing-any time you remove something-whether the CPU card or whatever else, it's a good idea to take a pencil eraser to the contacts and follow up by cleaning with alcohol. Once it's dry, insert and remove it from the socket a couple of times. Both of these processes can help to break up corrosion in the contacts, which is a constant enemy of computers of this age.