Re: Dead MMC. was: AAAA! My coil...

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Yurtle Turtle by way of Terry Fritz <twftesla-at-qwest-dot-net>" <yurtle_t-at-yahoo-dot-com>

What type resistors do you have? Is it possible that
you are blowing resistors, and that this is damaging
your caps? I blew a resistor on my MMC and it burned a
hole in the perfboard and burned my cap. Didn't appear
to hurt the cap, but it left so much carbon on
everything I replaced it anyway.

http://www.hot-streamer-dot-com/adam/burnt_mmc.jpg

Adam

--- Tesla list <tesla-at-pupman-dot-com> wrote:
 > Original poster: "Chris Roberts by way of Terry
 > Fritz <twftesla-at-qwest-dot-net>"
 > <quezacotl_14000000000000-at-yahoo-dot-com>
 >
 >
 > Well, crud.
 >
 > After reading the list posts and seeing that most
 > everybody agreed on
 > raising the resistors away from the perfboard, I
 > raised the resistors off
 > the perfboard by about 1/2 of an inch. I then put a
 > small square of plywood
 > underneath the one resistor that is in the spot that
 > keeps getting blown,
 > to better insulate it. I then fired it up.
 > Instantaneously, there was a
 > spark in that area, and I shut it down again.
 > However, I noticed that the
 > carbon mark was only on the top of the wood, not on
 > the bottom or sides
 > indicating an arc. I didn't pay much attention to it
 > at first, and thinking
 > it was solely the resistors fault, I took out the
 > blasted one and didn't
 > put in a new one. I figured the charge would just
 > bleed into the other
 > adajacent resistors. When the coil was fired up
 > again, it worked okay for
 > about 20 seconds, then a loud 'pop', and I
 > recognized that special type of
 > orange glow by the MMC. I rushed over, blew out the
 > small fire, and took
 > the coi! l in for the night. Rrrgh... there is a
 > beautiful (sarcasm) black
 > crater about 1/4 of an inch diameter in the top of
 > the cap that the failed
 > resistors were right underneath. So my coil is now
 > declared dead untill we
 > can get another cap.
 >
 > However, since there was no evidence of an arc, and
 > the cap failed seconds
 > after I removed the resistor, and since every other
 > cap and resistor are
 > doing fine, could the problem be the cap? It might
 > have been that the cap
 > was shorting out, dumping the charge across the
 > resistor, and when the
 > resistor was removed it simply carried the current
 > itself and blew up. Any
 > ideas?
 >
 > Also, (sorry about so many questions) someone told
 > me that with 2 strings
 > of 6 geek caps, the mmc is not suited to handle the
 > voltages at the peak
 > voltage. (9000VAC r.m.s. voltage, much higher peak
 > voltage) however, the
 > geek group recommended the current setup, so am I
 > okay as is or do I need
 > to redo my mmc completly? (I thought I was doing
 > fine, now I'm confused
 > again). Thanks.
 >
 >
 > -Chris
 >
 >