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Author Topic: U5000 Blooming issue  (Read 1119 times)

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castlesteve

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U5000 Blooming issue
« on: May 24, 2009, 09:47:44 am »

I have a U5000 that has an interesting problem.  It's geometry changes based on the input signal.  So a brighter picture will squish both top and bottom of the raster

It has had a new cap kit, swapped flybacks and the other standard U5000 checks.

Any idea?  I do I do thru each cap again?  I know they are all in the right direction

Thanks,
s
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qrz

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Re: U5000 Blooming issue
« Reply #1 on: May 24, 2009, 01:04:02 pm »
blooming is an effect of a weak crt .
it may be minimized by reducing drive ( pending gun condition) .
if resulting pic is too dark, rejuvination or crt replacement will be required ...


qrz
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castlesteve

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Re: U5000 Blooming issue
« Reply #2 on: May 31, 2009, 08:53:16 am »
it happens on multiple tubes.  ill try replacing the la7850 next
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qrz

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Re: U5000 Blooming issue
« Reply #3 on: May 31, 2009, 10:48:00 pm »
i re-read ur original post ( i hadn't got past blooming - sorry !!  )

the vert output ic is on it's way out .   
replace it and double check the bootstrap diode /cap
cathode should be higher v than anode when circuit functioning properly

qrz
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