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Main => Monitor/Video Forum => Topic started by: castlesteve on May 24, 2009, 09:47:44 am

Title: U5000 Blooming issue
Post by: castlesteve 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

Title: Re: U5000 Blooming issue
Post by: qrz 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

Title: Re: U5000 Blooming issue
Post by: castlesteve on May 31, 2009, 08:53:16 am

it happens on multiple tubes.  ill try replacing the la7850 next

Title: Re: U5000 Blooming issue
Post by: qrz 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