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Old 3rd Jan 2012, 1:43 pm   #11
IanF397
Retired Dormant Member
 
Join Date: Sep 2011
Location: Hatfield
Posts: 7
Default Re: Cossor CDU110 'Scope: Brightness Probs.

Hi Anthony,

In TV sets (CRT types) this kind of low brightness problem is often caused by low emission from the heater.

This can be caused by either a low emission tube (I know that you don't want to hear that !!), or by low heater volts.

Have you checked that the heater is nice and orange glowing ?

Have you checked the voltage across the heater ?
This may be tricky to do if the voltage is not DC or 50Hz AC.
In TV's this was often derived from a winding on the Line output transformer and was really pulsey, but had an RMS voltage of 6.3V or whatever.

The circuit that was posted did not show the heater voltage circuit, so I can't comment on this.

It is possible that low emission would also account for not being able to set the voltage on RV50.

Regards,

IanF397.
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