Help: Power Supply Died

[romeo.a.gatan]

I own a UNIX 7300 with 1 Meg and a 20Mb drive.  About three weeks ago,
my 20Mb drive died on me.  So I replaced it with a used one I got from a
friend.  It ran for about that length of time, then the whole system
went down on me.

Anyway, I opened the box and looked at the Power Supply board and
noticed that one component burned out.  This thing was in terrible
shape.  So bad that it looked like a raisin.

Anyway I need to find out what this component is.  It is marked as
RV1 on the board and it sits right next to C4.

Can anyone help?

Roy Gatan