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 Post subject: RCA HJ843W CTC28AA chassis no signal
PostPosted: Jun Tue 18, 2019 2:31 am 
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Joined: May Sun 08, 2011 8:52 pm
Posts: 520
Location: Bay City Mi
Picked this monster up for nothing, fortunately the picture tube was replaced in 1980, tested it and tests fair on all 3 guns, checked all the tubes , a few were really weak 1st IF, Shunt Regulator , one of the demod tubes... and the AGC tube was shorted ...Could not believe how bright the picture got after replacing that regulator tube. Since I don't have a digital box, I hooked up a dvd player to see how it looks ... I get raster and snow, and sound , but no signal ...I sprayed the tuner to the point of saturation , still nothing.. any ideas as to where I should check first? I know it will need caps... most appear to be the mylar type, not sure how reliable those are ...


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 Post subject: Re: RCA HJ843W CTC28AA chassis no signal
PostPosted: Jun Tue 18, 2019 7:40 am 
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Joined: May Sun 07, 2017 11:35 am
Posts: 591
Location: Belrose, NSW, Australia
You do NOT need to replace mylar or any plastic dielectric caps. Only wax paper types.

_________________
Wax, paper, bitumen, cotton, high voltages - what could possibly go wrong?


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 Post subject: Re: RCA HJ843W CTC28AA chassis no signal
PostPosted: Jun Tue 18, 2019 3:29 pm 
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Joined: Apr Sat 06, 2013 2:18 pm
Posts: 492
Location: New Hampshire
Try the fine tuning. Its about all that will cause that symptom.
If not try the AGC control.

73 Zeno 8)
LFOD !


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 Post subject: Re: RCA HJ843W CTC28AA chassis no signal
PostPosted: Jun Tue 18, 2019 4:07 pm 
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Joined: Nov Thu 11, 2010 6:03 pm
Posts: 966
Location: Pewaukee, WI
When you replaced the HV regulator I hope you measured the HV and set it to the value specified on labels in the set or service documentation....If your HV is set too high it can cause the flyback to eventually burn up....also want to adjust H Lin/efficiency coil for minimum H output cathode current for the same reason.


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 Post subject: Re: RCA HJ843W CTC28AA chassis no signal
PostPosted: Jul Sat 06, 2019 11:45 pm 
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Joined: May Wed 11, 2011 6:24 pm
Posts: 55
Location: Palm Beach County, Florida
Is there a disturbance when you turn the tuner? If so, look to see if the antenna ballun coil has been blown. past lightning strike) this will be at thye back of the tuner where the antenna wire connects and is external to the tuner assembly. Good luck. Snow, sound, and a bright raster is a great sign of survivor !


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 Post subject: Re: RCA HJ843W CTC28AA chassis no signal
PostPosted: Jul Sun 07, 2019 6:23 am 
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Joined: Nov Mon 02, 2009 7:01 am
Posts: 3848
Location: Lincoln City, OR 97367
Greetings to Bones007 and the Forum:

I strongly second Electronic Memory's post... if the raster suddenly got a lot brighter with a change in shunt regulator that would mean higher HV... not good. I don't recall what regulation scheme is used in the CTC28; I got out of the business around the time the CTC25 came out, but for sure, you need to set the HV and tune the efficiency coil, even if it is a pulse type regulator and not a 6BK4.

Regards,

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Jim T.
KB6GM


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