If you have an old house that has fuses rather than circuit breakers,
look for corroded fuses. I have seen fuses get corroded and give
intermittent problems even though they may be screwed in tight. Also
poor connections at the outlet. Loose screws on the outlet wires and or
loose screws at the fuse panel.
These type of poor connections often "cure" themselves temporarily when
high current is drawn through them. They arc and weld themselves closed
enough to conduct for awhile.
My first bet however would be poor connections at the power pole to the
drop to your house. Had that problem here. Had intermittent noise on the
line and would keep tripping the UPS supply. It was fast enough that it
could not be seen with a voltmeter on the line. I finally convinced the
power company that they had a bad connection at the transformer. Sure
enough there splice was partially burned and looked awful.
I have some large air conditioners that draw a lot ac power among other
thing in the house. They all ran fine but the arcing would cause high
noise on the line intermittently.
73
Gary K4FMX
Thomas Hix wrote:
I am my wits end with a recurring problem, and I am hoping maybe some of
you may be able to help me.
The last two amps I have had both seemed to be arcing internally somewhere.
The first amp I had problem with was an Emtron DX2SP......The high
voltage meter would deflect downward slightly and there would be the
sound of an arc inside the amp......you know a buzzing sound that sounds
just like a small arc to ground.
We took the amp apart and for the life of us we could never find an
arc......I sent the amp to a friend who is a major repair shop for amps
and rigs, and it would never do it at his shop.....never.
We got it back, and it started doing it again here.....slight deflection
of the high voltage meter and the buzzing sound inside the amp.
I got disgusted and sold the amp......and then I bought a like new Alpha
77SX with 2 8877's.
I used it a few weeks and no problem.....I was getting about 4kw out
with 100 watts drive (into a dummy load of course) and the amp just
worked wonderfully.
Then a couple of weeks back, it started doing the same exact thing as
the Emtron DX2SP had done.......the high voltage meter would deflect and
the arcing sound was there just like in the Emtron DX-2SP.....I had the
Alpha taken to my friends shop.....He took it completely apart and
checked everthing....every wire....every connection for any break or
sign of arcing.....nothing....he even checked the oil filled
capacitor.....it was fine.... and he ran it for 3 weeks, and he never
once had any sign of arcing or any meter deflection......nothing....once
again, the amp ran beautifully at his shop and he used it on the air for
3 full weeks.....nothing.
He brought it back home to me Sunday......we hooked it up, and there it
was again......it was once again making the arcing/buzzing sound inside
the amp, and every time it did it, it was making the high voltage meter
deflect downward at the same time the arcing/buzzing sound would happen.
OK that is 2 different amps that had the same exact symptoms while at my
location hooked to my 240 line.......both amps were making the
arcing/buzzing sound inside the amp and both were showing a downward
deflection on the high voltage meter.......both amps worked wonderfully
with no sign of arcing/buzzing and no high voltage meter deflection when
hooked up at my friends shop.
That can only bring me to one conclusion.....there is something wrong
with my 240 line?????
My question to the group is this......Could a problem with my 240 line
cause these amps to make an arcing/buzzing sound inside the amp that
sounds just like something is arcing to the cabinet without this
actually happening.....I can see where if I have a bad connection or
something like that inside my breaker box or even on my 240 wall outlet
I might see a deflection on the high voltage meter, but could that also
cause there amps to make a noise like something is arcing inside the amp???
I tell you this has really got my goat......I cant imagine what a bad
240 volt connection could do to there 2 amps that would make an arcing
sound inside the amp, but there is no arcing to be found??? We have
looked inside the amp with all the lights out at night when any arc
should show up, but we can not see any kind of arc.....so I am thinking
there is some component inside the Emtron DX-2SP and the Alpha 77SX that
will make that kind of arcing sound.....even though it does not
arc......when it loses either ground or voltage on the 240 line for a
split second.
I am a handicapped person so I cant check out my 240 line myself. I live
in an old house and there is no telling what can be wrong with the 240
line.....but I need a starting point....some things to look at when I do
get someone to come and see if they can get this thing figured out.
I am open to any suggestions and or diagnosis.......I NEED HELP! This is
driving me nuts.
Thanks!!!
73
Tom......W4TH
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