Crosley 9-403m Help Needed

[earlyfilm]

Originally Posted by cdmarion

I've got a crosley 9-403M that I restored 2 years ago . . . . . I turn on the set and get no raster at all EXCEPT when the brightness is turned all the way bright and I turn it counterclockwise fast then a raster with retrace lines will appear for a second and then it goes dark. . . . voltages in the vertical . . . . pin 4 of the vert. osc-discharge tube V-14, Sams calls for -2--5vdc and I'm getting a -41vdc. Any Ideas where I need to start looking? Any help is greatly appreciated.

Lets think about your symptoms.

If you had a minor problem in the horizontal, you would get reduced width and picture blooming as you advanced the brightness.

If you had a major problem in the horizontal, you would get no HV and you seem to have that.

If you had a problem in the vertical, you would get reduced height, or a single white horizontal line.

These symptoms more or less eliminate Horiz, Vert and HV issues.


OK, thinking the symptoms through, this problem can be caused by a wiring error or component failure in the vertical blanking circuit.

1) So, that one voltage error in the vertical may or may not be the result of that, so check carefully the wiring where the vertical pulse is fed to CRT to create the vertical blanking pulse.

2) Check the resistors on both sides of the brightness control.

3) Check the voltages on the video output tube.

4) Check the voltages on the CRT.

5) Depending on whether or not the video is fed to the CRT cathode or grid, you will have a relatively large cap on the other. That cap is suspect.

6) Although HV creation is not suspect, the resistance of that line is, so measure the resistance between the filament of the 1B3 and the CRT anode after carefully discharging it.

7) Mouse pee works wonders, so a corroded CRT socket not making electrical contact on a pin. (Less likely a defective CRT base solder joint, or the CRT itself.)

Sorry for being so vague, but I don't have a schematic of this set available and this is from memory of the 1940's tuning-indication Crosley's.

James