Re: System Saver IIgs -- ID of burned part?

["Mark Cummings" <NOTfigjams@primus.com.au>]

Mitchell,

I thought you'd be the one answering the questions, not asking them ! :)

Sorry I don't have one that I can look at, but if you are able to provide
more info on what is written on it, that may help.

If it's across the mains input (Active and Neutral, or Active and Earth, or
Neutral and Earth), then it is not a capacitor, but more likely a MOV (Metal
Oxide Varistor). These are used to protect spikes on the mains from getting
into your equipment. They may have a voltage rating on them. In my country
they are normally rated at 275VAC for our 240V Mains, but in US they would
more likely be 130VAC. There is normall 1, 2 or 3 of these in a Suppression
type Power Supply, and they are normally near to a couple of coils of thick
enamel wire around one or two toroid cores. The better ones have 3 MOVs
placed across each all 3 Active, Neutral & Earth inputs. If they are cracked
it would indicate a hit from lightning on the lines. If the are blown, they
no longer do their job and the next hit may fry your machine. Your
"Kensington System Saver" might just as well be called a "Kensington Fan" :)

I am restoring my own system saver, it's a Applied Engineering Conserver
(made for the US market). I have to build my own circuit and circuit board
because the one I have was gutted and just a 240V fan and bodgy power switch
was put in. The circuit I have copied and modified uses 3 MOV's, one big
20mm and two smallewr 12mm units. The ones I have are medium blue in colour
with a diagonal hump across each face of a coin (3/4" dia) sized disk.

If the disks are across the 12V supply parallel to the fan, then they could
be capacitors, but 3 sounds unlikely, normally 1 or 2 different value caps
would be all the is used for noise supression. Also capacitors use different
methods to specify the value. like 103, or 0.1, or 1uF or even coloured
blobs of paint. This is different ways to specify it's value, It normally
states a voltage under that too, like 35 or 50.

Regarding the use of other fans, yes if they are the same voltage and type,
ie 12V DC 100mA. If they are different current (mA) or wattage (W) it may
load your supply more or less. If the current or wattage is less on the new
one, then that should be no problem, but you may get less CFM airflow
through your machine.

Anyway, let us know what's written on those disks or a picture might help
too. What is it's dimensions etc...

Mark


Mitchell Spector <a_specto@alcor.concordia.ca> wrote in message
3b2ee077.13731649@newsflash.concordia.ca">news:3b2ee077.13731649@newsflash.concordia.ca...
>     I just opened up my Kensington System Saver IIgs to have a look
> inside (I've been wanting to replace its noisy fan for years) and just
> found something I wasn't expecting. The orange disc-like part at
> location 'V1' (there's also one at V2 and V3) split open and the
> plastic cover above it is badly scorched and burned. It looks to be
> some sort of large capacitor, resistor or regulator--I'm not sure,
> only that I've seen these on other electronics only much, much
> smaller in size. It has two points that solder to the board, probably
> a postive and negative contact.
>
>     The fan, LEDs and power-outlets seem to be working just fine, so
> I'm wondering what this bit of electronics does and how safe is it to
> continue running with it blown. Is it a fire hazard? I have absolutely
> _no_ idea when it blew, it could have been last week or it could
> have been 10 years ago.
>
>     Incidentally, can I use an ordinary 12v DC fan (say from a AT/XT
> powersupply) if/when I get around to opening it up again? The
> existing fan is huge, probably about the size of a refrigerator fan!
>
> Mitchell Spector
> a_specto@alcor.concordia.ca
>
>