22 Feb 2007

How to calibrate EIII power supply


Thanks to Dr C., here is the complete calibration procedure for the EIII power supply.

READ CAREFULLY AND COMPLETELY BEFORE ATTEMPTING ANYTHING !!!

IF SOMETHING IS NOT CLEAR OF EVEN OBVIOUS IN OUR EXPLANATION,
JUST STOP !

Required equipment :

a) - Small isolated crewdriver compatible with the power supply adjustable
b) - Digital voltmeter with correct batteries (to be sure the voltage
reading is accurate)
c) - PCB cleaner (KF-F2) for example
d) - Black permanent marker (the kind to be used to write in CDs)
e) - EXTREME PRUDENCE, TAKING YOUR TIME AND THINKING OVER WHAT YOU DO.

PREPARATION

Put the Emu in a very stable position and well lighted

TAKE AWAY THE MAINS PLUG (220V), THE METAL PARTS OF THE POWER SUPPLY ARE ON
LIVE, EVEN IF THE POWER SWITCH IS OFF, AND THESE ARE LETHAL VOLTAGES.

Take off the top cover

See the adjustable on the power supply.

Using the permanent marker, trace a mark to be sure to find how it was
adjusted.

Verify if the screwdriver is compatible.

Set the voltmeter to voltage measurement, continuous current, at 20 V
caliber (for example).
Put a probe on one of the yellow cables of the card cage connector (not on
the power supply connector, see picture) and the other on the chassis, for
example.

Put the power plug on and put the machine on.

You must see a voltage around +5 V on your voltmeter. If not, something is
wrong. Verify where you have plugged the voltmeter and retry.

If yes, shut the machine down and take the power plug off the machine.

STATUS : Machine "OFF" and power plug away.

Put some PCB cleaning product on the adjustable and turn the adjustment
around with the screwdriver (to clean the inside of the adjustable).

Put the adjustable completely leftwise (anti clockwise) or more : like a
volume potentiometer to the minimum).

Go have a beer for 15 minutes, the time it dries.

Put now the cursor of the adjustable half way from the minimum and the
trace you have made with the marker.

Check everything, voltmeter probes in place, cat away, etc...

ADJUSTMENT

Power the Emu. You must read quite a low voltage (around 3 V) and the hard
disk doesn't even start.

This is normal

Gently turn the adjustment, clockwise, and the voltage should climb. If
not, something is WRONG.
As well, if you get to the trace you have done and the voltage is still
low, DO NOT OVERPASS THIS TRACE !!!!

The hard disk should start spinning around 4 - 4,5 V

Increase the adjustment until you read : 5,05 V. Not 5,5V, I say : 5,05 V.

Once you are at it, shut the machine down, do not attempt to perform any
bank load or anything else, the machine didn't start accurately whit its
normal sequence, so it will be crappy and you may even crash everything,
datas and hardware.

Take the screwdriver away, the voltmeter, put the cover and restart your
machine.

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