PM 5400 / 5500 Damage? Compatibility?

[pizzigri]

Ok, I apologize- it was not clear what were you asking. In reality, using a 630-6300 board in a 5-6400/5-6500 enclosure that also provides a 3.3v rail should not pose a problem as that pin is NC in most logic boards.(there are threads which detail this and how to make sure that indeed the pin is NC).
You can radily isolate the pins with Kapton tape for eade of mind in this case.
The thread you linked is of the problem the other way round, or how to fit a LB needing the 3.3V in an earlier enclosure that does not provide it.
ladtl, I’m not sure what you’re asking with the coin cell mod, many of us use adapters to replace the dangerous and expensive 3.6v pram batteries with standard cr2032a ?

 

[Phipli]

In reality, using a 630-6300 board in a 5-6400/5-6500 enclosure that also provides a 3.3v rail should not pose a problem as that pin is NC in most logic boards.

But it is absolutely critical that you verify this. Don't, whatever you do, assume that the pin is isolated as you would be shorting your PSU if you just plug the board in and it isn't isolated.

 

[ClassicMacintosh]

Ok, I apologize- it was not clear what were you asking. In reality, using a 630-6300 board in a 5-6400/5-6500 enclosure that also provides a 3.3v rail should not pose a problem as that pin is NC in most logic boards.(there are threads which detail this and how to make sure that indeed the pin is NC).
You can radily isolate the pins with Kapton tape for eade of mind in this case.
The thread you linked is of the problem the other way round, or how to fit a LB needing the 3.3V in an earlier enclosure that does not provide it.
ladtl, I’m not sure what you’re asking with the coin cell mod, many of us use adapters to replace the dangerous and expensive 3.6v pram batteries with standard cr2032a ?

OK, so, need to work out whether the pin is connected on the board. Does anything need to be done on the PSU side if connected/NC?

With the coin cell mod, got some Meowtoast but they seem to only be for compact Macs. What I'm asking is, can one just wire a coin cell battery to + and - on the board?

But it is absolutely critical that you verify this. Don't, whatever you do, assume that the pin is isolated as you would be shorting your PSU if you just plug the board in and it isn't isolated.

Is there a guide anywhere to safely verify this?

 

[Phipli]

Is there a guide anywhere to safely verify this?

Use a multimeter to measure the resistance between the pin in question and ground. If it is less than about 20 ohms, you need to mod the board.

 

[pizzigri]

Here are a couple ideas. The first photo is which pin needs to be isolated (or checked); tape the pin on the other side as well. the second photo is a simple adapter I made (the other board is for a relay, ignore it).

 

[LaPorta]

Flux as a term for TB? Never heard that one!

 

[Phipli]

Flux as a term for TB? Never heard that one!

Might have it wrong, could be other conditions.

 

[ClassicMacintosh]

Use a multimeter to measure the resistance between the pin in question and ground. If it is less than about 20 ohms, you need to mod the board.

Thanks, still have a lot to learn. So I put the multimeter on ohms, touch one side to the pin, and the other side to ... where is the best point?

Here are a couple ideas. The first photo is which pin needs to be isolated (or checked); tape the pin on the other side as well. the second photo is a simple adapter I made (the other board is for a relay, ignore it).

Great! That gives some direction for the future. Also have a couple of other computers with this battery style that would be great to replace with coin cells. That adapter is 1 side to + and 1 side to - on the board, right? No extra components?

 

[pizzigri]

No, I just salvaged a coin cell holder from an old PC mainboard and recycled the leads from the old battery - check for green corrosion first. i can post the gerber if you want but it’s really trivial.
also I use some adhesive velcro underneath the pcb to use the hookpad on the LB….

 

[GRudolf94]

On pre-PCI boards such as the 6300 you got, the 3.3V pin may or may not be wired to ground, depending on a couple components having been fitted or not. If not, it's just not connected and is safe to use in a natively PCI machine such as yours. Else, it'd short 3.3 to ground, and then you have to either modify the harness, or tape over that pin on the edge connector, etc. If memory serves me right it's the center pin on the bottomside but don't take that as gospel.

 

[pizzigri]

It’s the third pin from the edge of the board on both sides of the connector , as I pictured on the above image… it’s of a 630 that I tested in a 6500 harness and power supply.

 

[ClassicMacintosh]

Thanks all, please excuse my lack of understanding, still learning over here. So the multimeter (on ohms setting) goes on the third pin from the edge of the board, where is the ground pin to put the other multimeter probe on?

 

[pizzigri]

…they say an image is worth a thou words… any pin that connects to a black wire is GND. The pin that carries 3V in a 6500 harness would be the one where I wrote “3V”. This is a 6200 harness.

 

[ClassicMacintosh]

Ok! And more newbie questions - does it have to be plugged into the PSU to check this? Or can it be done with the board out? I put the red probe where you have GND marked, and the black probe on the pins adjacent to it (and 2 across - both black ones). Getting 0L. Swapped red for black, and tried the other side. Not plugged into power though.

 

[Phipli]

Or can it be done with the board out?

Do it with the board out only.

 

[Phipli]

Getting 0L.

This means there is no connection.

Make sure you check both sides.

 

[ClassicMacintosh]

So, measured top 3rd pin from the edge with 1 probe, and touched other to 4 & 5 (both black wires in the above photo). Repeated the same on the bottom, 0L. Changed ohms to 200, 20k, etc, no difference.

Did the same on a spare Performa 580CD board, and same results. Assuming I'm doing it correctly and they're both OK to use, without mods, if need be?

 

[ClassicMacintosh]

So, recapped the 6300 board and plugged it in - chimes and boots to ? screen. Next step is to do the same with the 580CD board and see how it goes.

Guessing this is now the world's slowest PM 5500!

There were a couple of alarming "snap" or "crack" sounds from the back of the CRT that lessened each boot - something to be concerned about?