My Brand New CTC-7!

[SwizzyMan]

Originally Posted by DaveWM

ok so the B+ is dropping too much across the two 1600 ohm resistors that drop the 385v to the 270v (you get 205 IIRC).

start by checking the resistance of those paired resistors (800ohm, let the meter settle down).

If the resistors check out there maybe a leaky 50uf that connects to the 270v side I would start with checking that for leakage at the rated voltage.

You need to get the power supply voltages right before trying to further trouble shoot the lack of vert deflection.

Can't seem to find those two 800ohm resistors. Where are they located?

[DaveWM]

two 1600 ohm in p should be 800 ohm total look at the schematic, it drops the 382v to 270v the 382v is at the output of the filter choke and 80uf filter cap.

from there you should see two 1600 ohm resistors, prob large WW types.

[Phil Nelson]

They are R104 and R105 in the factory schematic, each rated at 10 watts:



Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

[SwizzyMan]

Originally Posted by DaveWM

two 1600 ohm in p should be 800 ohm total look at the schematic, it drops the 382v to 270v the 382v is at the output of the filter choke and 80uf filter cap.

from there you should see two 1600 ohm resistors, prob large WW types.

One read 809 ohms the other red 810 ohms.

[DaveWM]

well they are connected in p so will read the same value.

That clears the resistors as an issue.

Next if you do not have a cap tester to check 50 uf for leakage, you will need to disconnect it, temp tack in a new one and power up to see if that brings the 270v back up.

C104-b on the RCA schmatic (not shown on the clip from Phil) look for the 50uf section of C104 and check for continuity of the connection to make sure you are disconnecting the correct tab of the can. The schematic show C104-A, this is NOT the one.

you are looking for the SQUARE mark on C104 not the 1/2 circle.

[SwizzyMan]

Originally Posted by DaveWM

well they are connected in p so will read the same value.

That clears the resistors as an issue.

Next if you do not have a cap tester to check 50 uf for leakage, you will need to disconnect it, temp tack in a new one and power up to see if that brings the 270v back up.

C104-b on the RCA schmatic (not shown on the clip from Phil) look for the 50uf section of C104 and check for continuity of the connection to make sure you are disconnecting the correct tab of the can. The schematic show C104-A, this is NOT the one.

you are looking for the SQUARE mark on C104 not the 1/2 circle.

But isnt that a can with multiple values? So how could I just use one 50 uf?

[DaveWM]

disconnect only C104B the Square, connect the disconnected wire to a pos of a 50uf cap neg to ground.

[SwizzyMan]

Originally Posted by DaveWM

disconnect only C104B the Square, connect the disconnected wire to a pos of a 50uf cap neg to ground.

I'd connect the ground to the ground pin on the filter cap? Please bear with my pure stupidity here please.