CRT: Brief contrast/brightness prob at start-up.

Jul 09, 2010 4 Replies
32" RCA Entertainment Series CRT. Had popping noise w/ no pic or sound. Replaced HOT and FBT. Now A-OK except: At start-up, every start- up, contrast/brightness is way low/very dark picture. After 3-5 secs it corrects and is normal. I even let it run for 30 hrs straight to see if it would freak-out in other ways. It didn't. Problem is quite sufferable, but I'd like to chase it down. Ideas? Thanks again!

Wrongly set 'screen' control on your new FBT ? Taking a while for the beam limiter to assess what's going on and correct for it ? If original FBT was faulty, beam limiter sense resistor in ground return gone high ?

Arfa

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BTW: RCA MODEL F32450 CHASSIS: ATC113CA1

I just dialed in the FBT by eyeball with it turned on. Tweaked both settings til I had what I thought was best picture. Then adjusted from menu settings. Should it be done another way? Everything else is kosher except for prob described. THX!!!

And where would I locate this little beast...approximately?

The setting of the screen control can be very critical, depending on the circuitry design, and the condition of the CRT. Usually, there is a point to measure a voltage on, and a critical voltage to set on that point, using the control. A service manual will usually be helpful for that. The beam current sense resistor, assuming that it has one in the position I indicated, is usually physically quite close to the FBT itself.

Please note though that the observations I am making are general to CRT TV sets from the last 20 years, and not necessarily specific to your make and model, which I am not intimately familiar with, it being a U.S. model, and my practical experience all being with U.K. models. However, that said, the circuitry design from what I've seen, is generally pretty similar in all but the front-end low level signal and colour processing circuitry.

Arfa

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