A1200 power supply/input question.

dabone

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I've got a 1200 that I'm using a atx power adapter with.
Sometimes I'm having stability issues with my Apollo 1240/40mhz accelerator. The Voltage at the atx adapter for the 5v is 4.97, I'm getting a .13 volt drop from the amigas power supply connector to get 4.84 on the internal pins of the power jack, by the time is crosses the board over to the floppy connector I'm down to 4.69. I read somewhere about a mod using the floppy power as a input for power, or is there something else I could try?
(I was thinking of using a larger gauge wire under the board to take power from the power jack over to the floppy, but don't know what kind of damage this may cause).


Later,
dabone
 

Powerpie5000

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I assume your still using the A1200 i sold you? I have no idea what the motherboard revision was as i never opened it but i know rev 1D4 and 2B boards usually need the timing fix mod to work with 040 and above CPU's. What board revision did that A1200 have anyway?
 

dabone

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It's a 1d.4, and yes I did the timing mods.

My worry is that the accelerator is only getting about 4.6 volts to it.
I thought the 040's were picky about getting a correct 5volts.

Later,
dabone
 

Zetr0

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@dabone

4.6volts is just to low.

I would say that the PSU you are using is either poor quality or on its LAST of last legs.

- solution -

Get rid of it and get a new one, it doesn't have to be expensive, just of a reasonable quality =)
 

Chinners

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4.6volts is just to low.

So, I guess the 3.6 measured at the floppy of my A600 is WAY too low :)

Get rid of it and get a new one, it doesn't have to be expensive, just of a reasonable quality =)

Can you recommend one? i.e. which one have you had success with? I tried with one, and it kept turning itself off after 10-15 mins
 

Zetr0

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4.6volts is just to low.

So, I guess the 3.6 measured at the floppy of my A600 is WAY too low :)

OMG!!! :blink:

your amiga booted at 3.6volts ?!?!?

_________________________________


Okay - I can recomend a type - A good quality 350watt (or more) ATX -

Trying to use a cheap mATX is going to end in a knighmare -

I would suggest one spends about £15-25 on a decent PSU.


I use and would recommend a Q-TEC: ADT-350: 350w Swtiching ATX PSU (have a look at my album)

The PSU Board itself is small enough to fit into either an A4000D psu housing or an A2000 (although you could also fit a small family of 5 in an A2000 PSU)
 

dabone

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@dabone

4.6volts is just to low.

I would say that the PSU you are using is either poor quality or on its LAST of last legs.

- solution -

Get rid of it and get a new one, it doesn't have to be expensive, just of a reasonable quality =)

The output at the supply is 4.97 volts, I've tried 3 different supplies, (I'm work for a computer dist, and have access to lots of different supplies)
I've used a spi, enlight, and thermaltake.

The problem is voltage drop off from the power jack and loss in the amiga itself. (I'm guessing more the power jack/connector)

So at the atx to amiga adapter I get 4.97, directly inside the 1200 on the power jack pins I get 4.84, then on the floppy connector I'm getting 4.69.


Later,
dabone
 

rkauer

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Then it's time to solder a wire inside your Amiga!

Locate the +5V, +12V and ground rails in the power jack and solder a dual mini-Molex connector (the ones used to feed the floppy drive). One for the drive itself and another to hook into the floppy power connector in the motherboard.
 

dabone

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Then it's time to solder a wire inside your Amiga!

Locate the +5V, +12V and ground rails in the power jack and solder a dual mini-Molex connector (the ones used to feed the floppy drive). One for the drive itself and another to hook into the floppy power connector in the motherboard.


What about just running some larger wires under the board from the power jack to the floppy connector?

(I don't like the idea of running wires from under the board and then having to split them, I prefer a cleaner method if it will work.)


later,
dabone
 

rkauer

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You mean wires under the motherboard? Not advisable since they can be hit by a trough-hole pin, perforate and short-circuit something.
 
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