CTC-40 focus issue
 

Im sure this has been covered a hundred times, but without a sams, the focus is all the way to the right yet it's still out of focus a touch.

What am I looking for, a resistor, a diode?

Thanks guys

Usually it's a drifted resistor, they like to go up in value, most of the time.

Does this set use one of those "barber pole" resistors the ctc-16/17 and others use?

nope. check and see if there is a wire that bridges a 3.3 meg, follow the focus lead to find it. you can clip the wire if it will not focus in and you are going fully low voltage. Thats what my service manual says anyway...

Check the CRT socket. Those get leaky, and you can tell by the focus pin being green and corroded. Usually once that has happened, you need to replace the socket, but you might get lucky if it just started (if that's even the problem here).

Charles

CRT socket is good. Pins are clean too.
And I'm not seeing that 3.3meg resistor either. I did however find a 66 meg barber pile resistor. Replaced it for good measure. No difference.

should be right off the center lug of the focus pot. can you check the focus voltage at the CRT pin, the man says 5100v there is a 4.7 meg 2 watt resistor in series with focus pin, may want to check that as well

well I might have run into a small (well moderate) snag... The Flyback does not look happy. A bit of melted wax on the bottom.. The core is a hair loose on the lug as well.

How do you test to see like how you do on tube sets off the horiz cathode current?

hmmm scr, don't know about that. what is the HV at?

I am sure it does not matter but whats the line swith set to normal or High?

Normal. What's this switch do anyway?

Darn. Missing my probe

Well I found the 3.3m resistor. Clipped the wire across it. Measures 3.5m powered it up and the focus is now worse clipped and won't focus in well. Is .2 m enough to cause problems?

actually I answered my own dumb question, lol, the resistor is not used in this application bridged. This would tell me I have low voltage im assuming. Wonder what my HV is running at.. Hmmm

the normal vs high deals with line voltage. I would try it at the High (used when line is high) just to see what happens, esp if you are over 120v at the outlet. It just swiches out a tap on the primary of the power trans.

I was thinking if the HV is not set then maybe the focus is out of range. yea need to find that prob and see where you are.

Found my probe.. The meters broken.. :(

Maybe ill just use my DMM... J/K :p

Dang...

Oh well there are several parts show on a single board that all seem to relate to the focus voltage, looks like some kind of doubler. I would just check what you can. My simpson 260 has a 5000v dc that I often use, sure it prob loads it down some but it still seems to read about the same (but better resolution) as my HV prob.

the only note I have in the schematic is the focus voltage should be between 16.8% and 20% of the anode voltage.