is this a U45 or an RCA clone?

U45 crt bias pot adjusts the G1 where the RCA adjust the cathodes.

the only way to get a picture or anything on the screen is with the bias maxed and still dark. bias ccw nothing on screen..

in that case I would try a new video out tube for starters.

i dont know if its the 45, 5 -45 -5 is stamped on the chassis its a gold color chassis if thats any give away.

it may be a clone because the rca 16 and 16x chassis uses a 12by7 but this one uses 12gn7

if that does not help trace from the bias pot to a 220 resistor and a .22 cap. the resistor should be isolated so you should be able to check in circuit. You will need to lift a leg of the cap and test with an old school cap tester for leakage.

Its not a clone if the bias pot wiring is as described (bias adj the cathodes of the diff amps, thereby the G1's) close but not a clone

oh and check the 27k power resistors in the plate circuit of the diff amps, should have 410v on one side.

g1 , solid colors the bias adjusts the voltage. and the bias pot is mounted on a board and there are resistors on that board and i checked all of them so it may be under the chassis, wish i had a schematic...

just look for a 220 resistor off the bias pot.

look for a 3.3 meg resistor that goes to one side of the user brightness control

there is one 27k high watt resistor 405 one one side and 244 on the other, and tests perfect. that 220, ohm or k.

the 220 ohm resistor on one end of the bias pot is fine. the .22 cap near the diff amps checks lower in capacitance then another good one i have but its good. it will be very difficlut to reach the bright pot to see if it has a resistor on it. well there is no resistor on the bright pot and without a schematic it will take for ever to find because this thing is a combo and all controls are on one side and has long wires with no plugs to detach from the chassis, omg...

lets stick with this for a bit, the 244 should be fed thru a 100k ohm to the G1, and should not be dropping to the 160ish you mentioned before, find the 100k resistors that have one end on the G1 and the other to the 405. Something not right, the 244 should be at G1 as well, there should not be any loss across the 100k resistors in the G1 circuit.

looking from the rear of the set
chroma board
left side
back of board
look between the tube in the corner and a exposed coil for the resistor.

ok there was 3- 27k resistors and they are all ok and there is a 100k resistor at each g1 wire and they too are good. and also one other 100k also good.