Amiga A3000T PSU tester hack.

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Don't Panic. Please wash hands.

    Here is an adapter cable that I made up while I was bord, it's been cold here in Idaho U.S.A. I made an adapter cable to use a pc PSU tester on the Amiga. This will work on the tower computer only. The pc motherboard uses the same male connector that will fin to the Amiga 22 pin PSU. I just soldered the pc PSU wires to the proper pins on the salvage connector.

    To remove the connector from the pc mother board is to use a heat gun, get it hot enough that the solder melts and then pull it with a plyer, wiggle it and it will come off like a bad tooth.

    Caution, it was too cold to do this outside, so I did this in my computer room, and it set off my smoke detector. The digital PSU tester does not show the -5v, and the Amiga doesn't use 3.3 volts. the other tester has LEDs and does show -5 volts.

    Is this a good way to test PSUs NO, but it's what's available on eBay and cheap. See my posts on what test equipment I use to test PSUs.

    Quote from A3000T

    Is this a good way to test PSUs NO, but it's what's available on eBay and cheap.

    ..and may therefore confuse people. Just because something is "cheap", it doesn't mean that it's money well spent. There is a clear difference between tools and toys, and these are clearly not tools. Thanks for posting this as a negative example.


    Jens

    -Jens

    I use the digital display tester on my load box, I have a pass-through cable to connect it to just to monitor the voltages. I use my Fluke and O-scopes for measurements. Just to see what testers do, I will sub each of the voltages with my bench power supplies and very the voltage and see if they give an alarm.

    -Jens

    I use the digital display tester on my load box, I have a pass-through cable to connect it to just to monitor the voltages. I use my Fluke and O-scopes for measurements. Just to see what testers do, I will sub each of the voltages with my bench power supplies and very the voltage and see if they give an alarm.

    Update on the PSU Testers. They are all junk; the digital tester could be useful as a multi voltage voltmeter. It does detect high and low voltages by blink voltages. The others are all led and resistors, just a bunch of green lights. I use the digital tester; I have a pass-through connector to the tester on my PSU load box this way I can monitor the voltage on one device.

    +5V low voltage blink 4.6vdc, high voltage blink 5.5vdc.

    +12V low voltage blink 10.6vdc high voltage blink 13.4vdc

    Any of these conditions you should not use the PSU.

    WARNING do not connect the A3000T PSU directly to any tester without the adapter cable.

    Quote from A3000T

    +5V low voltage blink 4.6vdc

    Since most (if not all) 3.3V devices use a low-drop LM1117-type voltage regulator, the minimum voltage on the 5V rail should be 4.85V, with ripple not dropping below that at any time. That means if you have 50mV ripple, your average voltage should be 4.9V or higher, otherwise those 3.3V regulators start to oscillate and potentially damage 3.3V chips permanently.


    Jens

    -Jens

    The picture is from the Amiga 3000T which does NOT have 3.3v that is why it shows LL and +12v2 is not present as well.

    This topic is using the PSU tester(s) on the A3000T (with adapter cable) not on a windozzz machine!!!

    Blinking voltage is a warning, blinking LL or HH is danger! There was NO instructions with any of the PSU testers.

    Quote from A3000T

    The picture is from the Amiga 3000T which does NOT have 3.3v that is why it shows LL and +12v2 is not present as well.

    I was not referring to 3.3V from the PSU - that's not available on any Amiga PSU.


    I'm referring to the minimum input voltage of modern Amiga expansions that generate 3.3V locally: Those have a minimum input voltage of 4.85V. That's why modern, expanded Amigas have a more demanding, stricter 5V rail specification.


    Jens

    I still don't know which voltage you referring to. Please give a pin or an output regulator you referring to or the voltage on the tester.

    Again, the 3.3V I'm referring to are not on the PSU and not on the Amiga main board. They are only locally on modern expansions (like Y2K and later) that use 3.3V chips.


    Jens

    Combine this with post#8, and you have a stricter requirement for the 5V rail - got it now?


    Jens

    Please don't make yourself too much work posting in this thread, as it only acts as a negative example of how to NOT judge if a PSU is suitable for an Amiga. With the amount of activity and pictures, people may think that iComp endorses such toys, when we actually don't.


    Jens