[Amps] Need Diagnostic help

[Don Havlicek]

Tom,
Have you measured the 240v lines at both your shack and your friend's?
My best guess is that your 240v line is either ultra-high in voltage, or 
the ground is NOT connected correctly and the two 'sides' are NOT equal 
in voltage.
Don
N8DE

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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