Hello Gary,
For what it's worth...
That same capacitor, 285-1222-00, was also used in the military version of
the 2235, It was used directly across the incoming AC lines just before the
full wave bridge rectifier as part number C904, and it did not have a
resistor in series with it..
I have a few partially stripped military 2235 mainboards, and they are all
missing C904, so I would guess that it must have been a component that had
problems.
Other 22XX scopes I looked at use a .0022 uF (2200 pF) 250 V capacitor for
C904.
tom jobe...
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----- Original Message -----
From: "Garey Barrell" <k4oah@...>
To: "Tekscopes" <TekScopes@...>
Sent: Thursday, September 18, 2008 7:55 PM
Subject: Re: [TekScopes] 2215 Problem
Stefan -
It's not right across the line. It's in series with a 470 ohm 1/2W CC
resistor (which now measures 19 ohms) and looks like a "snubber" across
the AC line "after" a series inductor. There's an MOV (250VAC) and a
.001 cap across the line just after the fuse on the "line" side of the
inductor. This unit is rated for 220 primary power, although it's never
been used on anything but 120VAC.
73, Garey - K4OAH
Glen Allen, VA
Stefan Trethan wrote:
I'm assuming this was the x-capacitor (across the power line)?
If so the very same thing happened to me and a fluke 8842a. It had just
come
from singapure, and worked just fine for a few hours beforehand.
The cap leaked a nasty brown liquid (and acrid smell). It stained my
fingers
for days. The cap was actually inside a Schaffner brand mains filter
module.
Anyway, if it was the x-capacitor, you should replace it with a rated x1
capacitor for mains filter purposes.
ST
On Thu, Sep 18, 2008 at 11:06 PM, Garey Barrell
<k4oah@...>wrote:
I was using my 2215 for an hour or so the other night, and moved over
to
the desk to look at something else. About 30 minutes later I heard a
"sizzle - pop" and smoke comes rolling out the back of the cabinet!
Both sides! I walked over and turned up the Brightness, and had a
trace. So I shut it off, took it out of the case and did a close
inspection. Nothing! I couldn't find my small TORX bits (don't ever
move.......) but everything looked fine. So I turned it back on,
measured the supply voltages and all were right on..... Scope seemed to
be operating normally!?!?!
Today, I found my little TORX bits, and removed the inductor (the
HUUUMMMMMM) from the back panel and lo and behold, on the main board
underneath the inductor cover was what remained of C926, fanned out
like
a Rolodex. P/N 285-1222-00, 0.068 uF @ 250 VDC, 20%. This is a tiny
rectangular 1/4" x 3/4" by 1/2" high epoxy thing. Of course none of
the
million and a half capacitors that I have will even come close to
fitting mechanically.
So. Anyone have a source for these things, or perhaps have an "extra"
one.
help.....
--
73, Garey - K4OAH
Glen Allen, VA
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