SE/30 PDS adapter w 5v power

[nickpunt]

Something I noticed over in Japan is this SE/30 dual PDS adapter, specifically with a daughterboard to supply 5v power. I've wondered about this need for additional power for accelerators (ofc needing the adapter card in addition to this) and those of us who try to cram in a bunch of PDS cards. Feels like this idea could be incorporated into @Bolle's ethernet+pds riser or anyone else working on these adapters.

Items on Yahoo Auctions JP

https://buyee.jp/item/yahoo/auction/m1083836784?conversionType=top_page_search

https://buyee.jp/item/yahoo/auction/g1083854929?conversionType=top_page_search#group=nogroup&photo=1

Builder website:

丸真商店Top

 

[Daniël]

It's there to supply 5V and 12V rails from an external DC brick to the PDS cards. Whether that's truly necessary is another thing entirely. Maybe the weaker PSUs in some SE/30s can't deal with a load of PDS cards and accelerators, but then why wouldn't you refurbish or replace the PSU, or have that done, if you're going to spend the money on expensive upgrades? This feels like a rather clunky solution, when compared to fixing/replacing the PSU.

 

[Melkhior]

From DCDMF3:
- Table 15-13 Power budget for a Macintosh SE/30 and Macintosh IIsi expansion card
Voltage, V Current load, A
+5 1.5
-5 0.1
+ 12 0.15
-12 0.1
* Note: For thermal considerations, the total power of the expansion card should not
exceed 7 W
That's not a lot - you can't even use the full 1.5A@5V (7.5W) if you want to stay in the thermal budget. I suspect the IIsi has more margins, as you get 2.5W for the adapter, and then it presumably support NuBus specifications (so another 10W or so).

It's very possible for a power-hungry accelerator, even more so for a combination of cards, to blow the power budget - and cause the SE/30 to overheat. I would advise double-checking if a fully loaded SE/30 is straining its power supply and/or thermal limits.

 

[cheesestraws]

Agreed; the power issue is only half of the problem. The heat issue is the other. And let's remember that Apple's cooling has never been ... stellar.

 

[Phipli]

If only people would stop replacing fans with lower powered/performing ones with an expensive advertising budget.

I'd generally recommend playing with another machine on hot days because if it is 30°C vs 20, you have significantly less ability to cool the machine.