I was in RF before retiring.

1. Notice the #10 or such wire that the cap is attached.

The large diameter has lower inductance and higher DC and AC current.
2. Since the cap is in series (and yes legs wiggle mean it is dead) Only AC
current flows. The value of the cap and the inductance of the total
lead set determines what frequency it is shunting. The inductor Z
when it turns on and turns off produces spikes. Switching hot does as well.
3. Notice the ones in parallel to the rectifiers (diodes). They keep RF
current from inside the diode which might arc on the internal die and kill
the unit. Down in the bottom right is a RF high voltage arc with a set
of arc points that are used to limit the output RF arc. If these eat back
then the voltage increases and can cause more problems. But normally,
this is a source of RF noise that can harm transistors and diodes.
4. The module below the bridge is a filter. Likely an RC but with the
'V51' that tends to indicate an AC item. So resistor for better control.
5. The resistor R2 is a minimum load.

Replace the caps - keep their leads short. Higher voltage is just fine.
Get the same value as in the spec - that is the 'frequency' it shorts...


Hope that helps.

Martin


Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member.
http://lufkinced.com/


Jim Chandler wrote:
dave wrote:
I just bought an old miller dialarc HF "whiteface" vintage. while
getting ready to test it, and cleaning it out, I noticed some of the
leads on the tiny capacitors in the main rectifier bridge are loose,
kind of like how quarter-inch round rod would rattle around inside a
piece of half-inch water pipe. they're "probably" bad, because of that
alone, I'd guess, but, umm, what exactly is the electrical function of
those four tiny things supposed to BE? like "what're they doing for me?"

here'a an extreme closeup of one of the 'loose leads' capacitors, next
to one of the four "big honkin" diodes in the bridge.
http://www.image-upload.net/files/53...or_closeup.jpg

here's a page from the owners manual, where they're descibed...
http://www.image-upload.net/files/5385/parts_blowup.jpg

and here's the parts schematic, for the same machine.
http://www.image-upload.net/files/53...0schematic.jpg

electrically, I'm a "real slow learner", so, thanks for your help,
guys :-)

toolie

they're probably to provide a DC path to ground for AC spikes.

Jim


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