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wingnut2001
Joined: 25 Aug 2010
Posts: 37
Location: Horse City of the world!
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| Posted: Sat Sep 11, 2010 1:43 am Post subject: |
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bottom line....somebody start making quads LOL
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jaredjaric
Joined: 05 Jun 2007
Posts: 228
Location: Philippines
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| Posted: Sat Sep 11, 2010 2:03 am Post subject: |
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| zGman wrote: | Try this link for an overview....
http://en.wikipedia.org/wiki/Fourier_series
Basically, as I understood it (so very long ago), a square wave
can be thought of as a construction of various frequency sine/cosine
waves. This has some real consequences, as the sharper the "corner"
of the square ware, the higher the amplitude and frequency of the
'component' sine/cosine waves. Tranformers are designed to work
at a nominal frequency, based on the magnetic permeability of the
core, etc etc..... So - running a square ware into a transformer is
going to create heat and inefficiency and stress, which could lead
to premature failure...
G |
oops fell asleep last night reading the threadlink  ,
will send and ask about it with e tech guy,would be very useful.Thanks.
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jaredjaric
Joined: 05 Jun 2007
Posts: 228
Location: Philippines
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| Posted: Sat Sep 11, 2010 2:09 am Post subject: |
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| zGman wrote: | Try this link for an overview....
http://en.wikipedia.org/wiki/Fourier_series
Basically, as I understood it (so very long ago), a square wave
can be thought of as a construction of various frequency sine/cosine
waves. This has some real consequences, as the sharper the "corner"
of the square ware, the higher the amplitude and frequency of the
'component' sine/cosine waves. Tranformers are designed to work
at a nominal frequency, based on the magnetic permeability of the
core, etc etc..... So - running a square ware into a transformer is
going to create heat and inefficiency and stress, which could lead
to premature failure...
G |
i believe you are saying that the transformer (cores )are not working at optimum,and the windings don't have to be necessarily shorting,so i guess the best bet is to replace everything in the quad if possible.
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zGman
Joined: 22 May 2006
Posts: 599
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| Posted: Sat Sep 11, 2010 4:05 pm Post subject: |
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Well certainly if the transformer is showing signs of damage such as cracked
ferrite or HV arc traces nearby - there can't be much question it needs replaced.
But I am also wondering if the input to the quad from the EHT is a square wave,
and if so perhaps that could explain the high failure rates, and then possibly - -
could the input signal be filtered without significantly changing the impedance.....???
G
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Sat Sep 11, 2010 5:14 pm Post subject: |
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The construction and application of the transformer along with the type of power supply being used determines if it will function better when input a square wave or sine wave.
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Ile
Joined: 09 Mar 2006
Posts: 1491
Location: Jyväskylä, Finland
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| Posted: Sat Sep 11, 2010 7:53 pm Post subject: |
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| zGman wrote: | But I am also wondering if the input to the quad from the EHT is a square wave,
and if so perhaps that could explain the high failure rates, and then possibly - -
could the input signal be filtered without significantly changing the impedance.....???
G |
Checked EHT schematic and it looks square wave to me, quad primary is connected to 300VDC and DHV signal. DHV is grounded by driver transistor and it's scope calibrated to 10uS off time.
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jaredjaric
Joined: 05 Jun 2007
Posts: 228
Location: Philippines
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| Posted: Sun Sep 19, 2010 3:13 pm Post subject: |
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| jaredjaric wrote: | | zGman wrote: | I wonder if the transformer is what breaks down under HV? Seems like it is
the component with the most electrical stress, and quite likely some
mechanical stress as well (yes - rapidly changing electromagnetic fields
create physical force - think motors, or feel an old buzzing x-former)
There is also heat - so add up the breakdown of insulation over time, with heat
and physical stress, possibly the windings start to short, possibly feeding
back HV into the EHT or changing the load profile.....
G |
all the parts passed the dummy load test,but i dont think the tech guy used enough voltage(no heat stress maybe).but he is suggesting tiny cracks in the quad case causing it to short.i do remember smelling of burning caps in the pj before,it is possible over a long period of use the insulation breaks down and arcs would burn holes on the plastics,...i think. |
Had the x'former checked for impedance again after prolong dummy load on quad.
Looks like a bad x'former,according to tech guy.He has the same comment with zGman.mIght also explain the presence of burning scent on pj before.
So replacing everything on the quad is mandatory.
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