[Amps] Need Diagnostic help

["Thomas Hix" <w4th@hotmail.com>]

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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