Date   : Wed, 15 Nov 2006 20:46:11 -0000
From   : robincommander@... (Robin Commander)
Subject: Master 128 Power Supply

Ah, you beat me to it :-)

One point I forgot to mention, and is also not made on your excellent web
page Sprow, is that these capacitors have to be installed the right way
round, so if replacing one make sure you orientate the new capacitor
correctly. Depending on their location (in an electronic sense as opposed to
a physical sense) within the PSU, a capacitor which is incorrectly
orientated may explode when power is applied.

Regards,
Robin


-----Original Message-----
From: bbc-micro-bounces+robincommander=blueyonder.co.uk@...
[mailto:bbc-micro-bounces+robincommander=blueyonder.co.uk@...
] On Behalf Of Sprow
Sent: 15 November 2006 20:25
To: bbc-micro@...
Subject: Re: [BBC-Micro] Master 128 Power Supply

In article <455B7428.1080307@...>,
   Richard Gellman <splodge@...> wrote:
> Flick the switch... nothing. Dead.  Take machine apart, all the 5v lines 
> read 0.1 volts on the voltmeter. Try powering up supply separately, 5v 
> lines now read 5v. Try reconnecting PSU to M128, switches on fine. Looks 
> of confusion abound. Drink consumed, though sadly no alcohol present. 
> Reassemble M128, and slide it back into position. Power on. Dead. 
> RAMPANT looks of confusion now. Go to unplug unit, M128 suddenly powers
on.
>
> Its almost like the PSU has developed a random time delay before it is 
> willing to provide power to the system.

A known problem. It's just taking a long time to startup, the larger the
load the longer it takes (which is why in isolation it starts up instantly
and appears to work fine), due to dry capacitor.

See
 http://www.sprow.co.uk/bbc/howto.htm#powersupply
along with a host of other frequently asked questions,
Sprow.


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