7500 Power Supply Woes

[macuserman]

I have a 7500 machine that was robbed of it's power supply by the previous owner and a few other parts. In trying to track down a powersupply cheaply for it I came across a 7200 for sale on marketplace it was a pretty good deal $80 including shipping so I figured that's perfect I will get my powersupply and a few other bits. Well it came today and what do you know the PSU connector is short by two pins!!! Ahhh!!! Does anyone know what the difference is and if I can jerry rig up the missing two pins or is the whole thing completely different?

Thanks in advance!

 

[macuserman]

My 7200 is a 22pin connector, and this 7500 board is a 24pin connector, info on the web is quite confusing about this most say they are all the same, which clearly they are not since well I have proof right in front of me.

 

[macuserman]

Alas it looks like I have a habit of answering my own questions, but anyhow I'll still share the info here in case anyone else ever needs it. I did find one other thread on here which gave me this helpful link with the actual pinout: https://modelrail.otenko.com/apple/power-mac-7200-power-supply



I decided to just grab the relevant info out of that link and put it here in case that link ever dies. Anyhow so that didn't solve my problem but did give me the 22 pin pinout.

I did some searching on ebay for examples and it appears that my problem might be that what I actually have in my 7500 case is a 7300 board part number: 820-0858-B which is easy to identify because the connectors for the power supply are straight and plugin from the top instead of being right angled and plugging in from the side. Pulling up quite a few auctions for motherboards and counting the pins on the connector shows me that most at least all of the examples I found, of 7200, 7500 and 7600 board all have the right angle 22pin connector. It appears I've just been incredibly unlucky in having a 7500 case without a true 7500 board in it. Looks like there is a mighty cheap 7600 board in Florida on ebay that is selling as a "working pull" with the right 22pin connector so I've ordered that and we'll see if I can't resurrect this machine after all. Just costs me another $36 dollars and another week of waiting for it to arrive so I can try it out...

 

[joshc]

Well, I learned something today. I actually thought all of the 7xxx series (except 7100) shared shared the same PSU pinout, but clearly not.

Thanks for posting the information, hopefully it will be useful to others.

 

[trag]

I'm pretty sure that the original poster's '7500' motherboard is actually a '7600' motherboard.

The only difference between the two is the power supply connector.

The 7500 and 8500 (and 9500) all use the same power supply connectors as the 7200. I've tested this in practice.

If the case says "7500" on the front, then someone probably swapped the logic board at some point.

 

[macuserman]

I'm pretty sure that the original poster's '7500' motherboard is actually a '7600' motherboard.

The only difference between the two is the power supply connector.

The 7500 and 8500 (and 9500) all use the same power supply connectors as the 7200. I've tested this in practice.

If the case says "7500" on the front, then someone probably swapped the logic board at some point.

I think I have to disagree with you on that, I'll post some pictures of them all side by side as soon as my other board arrives, but I've looked up a lot of pictures of these machines and the 7300 is the only one with the 24pin connector in any of the photos I've found.

Here's a picture of the 7300 board with the straight 24 pin connector.


Here's a picture of a 7200 with the 90 degree 22 pin connector:


The 7500/7600 boards have the 22 pin 90 degree connector like this:


These are just shots I pulled from the internet, but it shows what I mean as far as the two different styles, if you have an unmolested 7200, 7500, or 7600 and you pop it open I'm very confident your going to find the 22 pin 90 degree connector and only the 24pin straight on on a 7300. Not that google is proof, but if you google 7300 and look at the photos they all have that straight 24pin connector vs the other style.

 

[trag]

I think I have to disagree with you on that, I'll post some pictures of them all side by side as soon as my other board arrives, but I've looked up a lot of pictures of these machines and the 7300 is the only one with the 24pin connector in any of the ph

if you have an unmolested 7200, 7500, or 7600 and you pop it open I'm very confident your going to find the 22 pin 90 degree connector and only the 24pin straight on on a 7300. Not that google is proof, but if you google 7300 and look at the photos they all have that straight 24pin connector vs the other style.

this 7500 board is a 24pin connector

Your statements are inconsistent. If your '7500' has a 24 pin connector, then clearly the 7300 is not the only one with a 24 pin connector.

So, how did there come to exist what looks like a 7500 board with a 24 pin power connector? One possibility is that it is a 7600 logic board.

I have some small uncertainty regarding the 7600 and it's power supply connector, but if you have what looks like a 7500 board and it has half of the video chips on-board (as opposed to 8500 with all or 7300 with none) and a 24 pin power connector, then I'm fairly certain that's a 7600.

There was no other difference between the 7500 and 7600. They didn't change the ROM. They didn't change the chipset. They didn't change expansion connectors.

The only thing that changed between the 7500 and the 7600 was the power supply connector.

Then on the 7300 they eliminated the video In (out? can never remember which the 7500/7600 had) and the ROM changed to the same as the original 8600/9600.

The 7300, and both versions of the 8600 and the 9600 all use the 24 pin connector.

 

[macuserman]

Your statements are inconsistent. If your '7500' has a 24 pin connector, then clearly the 7300 is not the only one with a 24 pin connector.

So, how did there come to exist what looks like a 7500 board with a 24 pin power connector? One possibility is that it is a 7600 logic board.

I have some small uncertainty regarding the 7600 and it's power supply connector, but if you have what looks like a 7500 board and it has half of the video chips on-board (as opposed to 8500 with all or 7300 with none) and a 24 pin power connector, then I'm fairly certain that's a 7600.

There was no other difference between the 7500 and 7600. They didn't change the ROM. They didn't change the chipset. They didn't change expansion connectors.

The only thing that changed between the 7500 and the 7600 was the power supply connector.

Then on the 7300 they eliminated the video In (out? can never remember which the 7500/7600 had) and the ROM changed to the same as the original 8600/9600.

The 7300, and both versions of the 8600 and the 9600 all use the 24 pin connector.

I think all of the confusion is in assuming the board in my 7500 case is the original board which I'm quite confident it is not. These machines get mish mashed all the time, shoot I'm about to drop a 7600 board I ordered off ebay into a 7200 case and swap onto it the cover that says 7500.....

This case was completely gutted only thing left in it was this board and it came from my dads massive pile of computers which he swapped around any way he wanted to get things working. Really no reason to base all of this on the idea that the board in here is original, it could even be that the top cover was simply swapped and that's why it has the wrong label on it. I do have the board numbers and I'll post them up shortly it would be more helpful to try and verify using those I would imagine if anyone has any board numbers they can post that they are confident belong to the various models.

There was no other difference between the 7500 and 7600. They didn't change the ROM. They didn't change the chipset. They didn't change expansion connectors.

The only thing that changed between the 7500 and the 7600 was the power supply connector.

This is a very interesting claim, I'd love to see a photo inside your machines showing that this connector is different between the two.

-Ivan

 

[macuserman]

Your statements are inconsistent. If your '7500' has a 24 pin connector, then clearly the 7300 is not the only one with a 24 pin connector.

I was posting as I discovered things here and originally I was assuming that I had a genuine 7500 board which is why there are early comments in this thread saying that my 7500 has 24pin connector. However, as I discovered later I'm reasonably confident that is a false statement and I have a 7300 board here not a 7500 board. Anyhow I hope you don't mind the debate, I just would rather get to the bottom of things definetively so that there isn't misinformation left hanging around for the guy who comes along.

Still haven't found a pinout for the 24pin connector either, lots of info for the 22pin but no info on what those extra two pins are for that I can find yet.

 

[trag]

Don't mind at all and I hope I did not sound confrontational. I'm trying to be investigative and informative.

Easy enough to tell if you have a 7600 or 7300. The 7300 eliminated the video processing capability that the 7500/7600 had which means one or two of the main ASICs on teh board are missing, but a few were already missing because it isn't an 8500/8600. So it can be difficult to determine if the right one is missing.

Easier, if the board is out of the case, is to flip it over and look at the four ROM chips. They are about 1.1" X .5" and have 22 pins down each long side.

On the 7600 they'll be labeled 343S0169 through 343S0171 (might be 341 instead of 343, I can't remember). On the 7300 they'll be 34xS0280 through 34xS0283.

 

[mg.man]

FWIW... I have an original 7300/166 and a 7600 'board. Here are pics of the 7300 Power Connector...



...and here are images of the 7600 Power Connector...



So... 7300 = 24 pin, "upright" and 7600 = 22 pin, rt-angle.

HtH

 

[joshc]

Here is the information from the Apple service source manuals for these models... I was hoping this would clear it up, but both of these diagrams seem to have the same edge 90 degree connector !?

The following drawing shows the Power Macintosh 7200 logic board.




The following drawing illustrates the connectors on the Power Macintosh 7300, 7500, 7600 and WS 7350 logic boards.

 

[mg.man]

I was hoping this would clear it up

HA!! Clear as mud maybe!!! See my pics... that's a "real" 7300 and "real" 7600... different connectors. Could there have been multiple board revisions on the 7300???

 

[macuserman]

Don't mind at all and I hope I did not sound confrontational. I'm trying to be investigative and informative.

Easy enough to tell if you have a 7600 or 7300. The 7300 eliminated the video processing capability that the 7500/7600 had which means one or two of the main ASICs on teh board are missing, but a few were already missing because it isn't an 8500/8600. So it can be difficult to determine if the right one is missing.

Easier, if the board is out of the case, is to flip it over and look at the four ROM chips. They are about 1.1" X .5" and have 22 pins down each long side.

On the 7600 they'll be labeled 343S0169 through 343S0171 (might be 341 instead of 343, I can't remember). On the 7300 they'll be 34xS0280 through 34xS0283.

343S1141-02
343S1141-02
343S1154-A
343S1155-A

Are the part numbers from the back of the board, I will say it does not have the connector on the board for the AV inputs, not sure about any other chips it is missing though. I have seen pictures online of a 7300 that had the connector though as well initially I thought that was a clue, but then changed my mind later.

Like this board here on ebay which says it is from an 7300 and has the 24pin connector but then also has the AV input socket right by the PCI slots.

APPLE POWER MACINTOSH 7300 LOGIC BOARD 820-0858-B | eBay

SOLD FOR SPARES ONLY.

www.ebay.com

Where my board which is pictured here this is the actual board in question does not have it.

 

[macuserman]

So... 7300 = 24 pin, "upright" and 7600 = 22 pin, rt-angle.

This is what I was thinking after doing my digging around. Would you mind sharing your board number on your 7300 to compare with my board in question? My board has part number 820-0858-B

 

[trag]

I agree. I believe that Ebay listing is wrong and that is a 7600 board. Actually, I'm pretty certain that's an 8600 board. The two extra chips near the center are usually missing on the 7x00 series.

You appear to have a 7300 board, but it's interesting that your ROMs are different. If you are able would you please post a photo of the back of the board, possibly with close up of the ROM chips.

I've never seen one that didn't have the 0280 - 0283 set before.

 

[mg.man]

Would you mind sharing your board number on your 7300

Let me go open it up again... Stay tuned...

 

[macuserman]

I agree. I believe that Ebay listing is wrong and that is a 7600 board. Actually, I'm pretty certain that's an 8600 board. The two extra chips near the center are usually missing on the 7x00 series.

You appear to have a 7300 board, but it's interesting that your ROMs are different. If you are able would you please post a photo of the back of the board, possibly with close up of the ROM chips.

I've never seen one that didn't have the 0280 - 0283 set before.

Hmmm so your thinking that link I posted above is a 7600 because it has a 24pin connector and a A/V connector?

For whatever it's worth this is the actual listing I purchased that is claiming to be a 7600 board that has both the AV connector and a 22pin right angle connect that will be here Friday.

Apple Computer 820-0752-a Circuit Board 8200752A for sale online | eBay

Find many great new & used options and get the best deals for Apple Computer 820-0752-a Circuit Board 8200752A at the best online prices at eBay! Free shipping for many products!

www.ebay.com

I'll get you some pictures of the back of the board in question in a little bit.

Let me go open it up again... Stay tuned...

Cool, also just out of curiosity does your board have the AV input connector or no?

 

[mg.man]

Here are pics of my board...


...and part number detail...

does your board have the AV input connector or

Um... not sure, but don't think so...

 

[macuserman]

Um... not sure, but don't think so...

No it doesn't it's the double row of pads/holes right above your third PCI slot between the PCI slot and the CPU card toward the port side of the case. It appears we both have the exact same part number and are both missing the AV input port. Which makes me pretty confident that I've got a 7300 board as well.

The only real question I have is if the 7300 did have an option to ship with the AV input slots and it appears it does if we go off the ebay auction I posted earlier which shows a 24pin connector and has the AV input. It has the same board number as our two boards if you look at his close up shot. https://www.ebay.com/itm/224511722927?hash=item3445f105af:g:rKkAAOSwyx1gWPeF

I'm satisfied that the 7300 had a 24pin connector, and 7200, 7500,7600 all seem to have the 22pin connector in the examples we have seen so far, but Trag still seems really confident that the 7600 has a variant with the 24pin connector at the very least if not all of them for some reason since as he was saying that link I posted earlier was probably a 7600. So with that in mind I suppose it's possible that there are some 7600 boards with a 24pin connector? Although so far I haven't seen any boards claiming to be a 7600 that had it.