Curtis Mathes FF500M no vertical
 

I finally dug my CM FF500 out of storage and began to tackle its electronic ills. I have no vertical deflection although horizontal is full width. My first thought was the 6GF7 vertical osc/output tube. Are these known to fail in these sets (a reworked CTC16 I understand)? Are there other common-failure components I should go about checking?

Thank you

Always check tubes first. Best to replace caps in that section to start. Dirty tube sockets or a bad/dirty vertical hold or linearity pot. make sure the filaments are lighting up in all the tubes if possible. Check solder joints on the PC board if it has one. I had a problem like that in my ctc-9 and it tuns out I had a broken wire at the vert control pot. Sometimes it's simple, My CTC-16 had a weak 6GF7 on one side of the tube. It had a decent picture but could not adjust it to full height. After replacement with a NOS tube, it works great. Try these first and let us know.

Om thr rcas corroded connections and corroded off wires are an issue onder the chassis near the vert out transformer and power resistor. Move the tube around in the socket. Other than that start checking voltages. Ohh and check for a dirty bad whisker shorted service switch move it bacK and forth

Make sure the service switch on the rear apron of the chassis is in the normal (not service) position. Operate the switch vigorously a few times as these can be plagued by dirty contacts.

Thanks for all your help on this. Lots of good brain jigglers.

Filaments light, tube checks OK in my basic tester (doesn't do mutual conductance or those fancy features though), and I've played with the service switch. Cleaned the contacts with DeOxit, cleaned the switch with DeOxit. Wiggled tube in socket. No change. [sigh]. So much for easy things. Strange thing, the service switch in "normal" gives the horizontal line, but in "service" it gives no raster. That doesn't sound right, does it?

Check the resistors coming off of the vert lin/height controls. There is one that is known to go bad, though when it does it usually means a short raster, not zero vertical. If nothing there, I'd confirm that the pots are okay. (you could jumper them as a test)

Check pin 6 of the 6GF7, it should be around 400volts, only check this pin when you have no vert sweep or you may fry your meter. Even better is to pull the tube out and check socket pin 6.

Check pin 8 with the tube in, should be over 150 volts.

If one of those is missing you wont have any vert.

Pin 3 is the cathode, 16 schematic says 85 volts.

I would really be looking at pin 6, that will check the secondary of the vert out transformer, the power resistor and connections. If the .001 shorted and took out the power resistor etc.

Thanks CTC17 I'll have a go at that!

The service switch would normaly kill the vert and reduce the brightness. Screen controls for each color would then be adjusted for Very dim grey/ white line with no color tinting. Do you hear the vertical buz from the Vert out trans? If not keep trouble shooting as you are. If you do it could be the yoke.