I assume the Key-switch had an Open-Closed connection (Closed locks out the keyboard and mouse) and a Reset connection built in (closed causes a hardware reset). I've not run across such a combination; good luck on finding that one... But no, they have no bearing on the PSU; rather than find an exact replacement have you thought about: 1) having that one repaired (it is old school tech and a TV repair place should be able to fix it), 2) replacing the insides with a new, and smaller PSU, or 3) finding a similar "box" and grafting the wiring harness?
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Amiga 3000T Power Supply Connector
This is a description of the power supply connector ON THE MOTHERBOARD of the Amiga 3000T
series.
PIN Description PIN Description
1 TICK 13 FAIL
2 -12V 14 +12V
3 -5V 15 +12V
4 GND 16 +5V USER
5 GND 17 GND
6 GND 18 GND
7 GND 19 GND
8 GND 20 GND
9 +5V 21 +5V
10 +5V 22 +5V
11 +5V 23 +5V
12 +5V 24 +5V
Taken from the Amiga 3000T Schematics in the back of every Amiga 3000T manual.
These voltages are found on standard AT power supplies. Tick is not found on modern PSU’s and a motherboard jumper (J300 on an A2000) sets it to internal
Pictures can be found here:
http://www.allpinouts.org/index.php/File:Connector_amiga3000tpower.pnghttp://aijaa.com/img/b/00601/5622021.jpghttp://amigakit.leamancomputing.com/catalog/product_info.php?products_id=998http://media.bestofmicro.com/Power-Supply-Fundamentals,8-2-312626-13.jpg