[H-GEN] Wanted: Powermac 7200/120 power supply

[Tim Callaghan]

[ Humbug *General* list - semi-serious discussions about Humbug and
Unix-related topics. ]

On Mon, 4 Oct 1999, Bradley Marshall wrote:

>
>Does anyone have a spare PowerMac 7200/120 power supply that
>they can part with?  I have a suspected dead power supply here..

You'll find these pretty hard to come by, since they are what Apple call
an exchange part, meaning that you buy a new one and send the dead one
back to Apple, and in return get a pretty massive discount for the part.
For example, to buy it new would set you back about $350 ex tax RRP, but
to do the exchange would cost about $195 (tax irrelevant)... Apple do this
for almost all of the more interesting or useful parts of their computers.
For your information, the Apple part number is 661-0920, and this is used
in the PM7200, 7300, 7500, 7600 and Workgroup Server 7250, except the
200MHz versions of these models. They have a beefier power supply.

If you take the machine to any Apple reseller, they should be able to test
the machine and tell you exactly what the problem is. My first tip is to
check the PRAM battery. If it's reading below about 2.8 volts, replace it,
because that could well be the problem. Other things to check are SCSI
termination and IDs (although these would normally not cause a no-power
symptom), verify that the RAM is NOT EDO, as EDO memory will kill these
machines (like, damage the logic board). Use only 5 volt Fast Page Mode
DIMMs.

These are the steps that Apple recommend following when a 7200 has a no
power fault:

1 Reseat ROM SIMM (if present).

2 Reset Cuda chip.

3 Reset logic board.

4 Replace power supply.

5 Replace logic board.


The Cuda switch is a micro switch on the motherboard. There is only one,
and it is labelled "CUDA" or "CUDA RESET". To reset the Cuda chip, press
and hold this switch for 10 seconds.

This is what Apple says about resetting the logic board:

Whenever you have a unit that fails to power up, you should follow this
procedure before replacing any modules.

1 Unplug the computer.

2 Remove the battery from the logic board. (See Take Apart for
instructions on how to remove the battery.)

3 Disconnect the power supply cable from the logic board and then press
the Power On button. (See "Logic Board Diagram" later in this chapter to
locate the Power On button.)

4 Wait at least 10 minutes before replacing the battery. Make sure the
battery is installed in the correct +/- direction.

5 Reassemble the computer and test the unit.

Note: This procedure resets the computers PRAM. Be sure to check the
computers time/date and other system parameter settings afterwards.

I personally recommend resetting the Cuda chip whenever you reset the
logic board, just for completeness.



>
>Or, if not, does anyone know where to get a convertor so I
>can use the monitor on a standard pc?  The specs would be HD15
>male to D15 female, from what I can tell.

I hate to advertise my place of work, but we can do them for about $50 I
think. However, the markup on cables and adapters is pretty huge, so I
would be inclined to be flexible on pricing. ;)

>
>Thanks,
>Brad
>-- 
>Bradley Marshall
>Sysadmin
>Plugged In Software
>

Hope this helps.

cheers,
Tim Callaghan
Service Technician
Mac's Place

+---------------------------------------------------------[Tim-Callaghan]-+
| On a le desire, on se dit il faut agir, mais cette                      |
| lachete inavouable nous rend bien trop gouvernables                     |
+---[Stereolab]-----------------------------------------[emrys at uq.net.au]-+


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