Zenith Advanced System 3 help needed

[holmesuser01]

I'll look and see what I have tomorrow. (It's dark here.)

[pac.attack76]

Originally Posted by holmesuser01

I'll look and see what I have tomorrow. (It's dark here.)

Ok, i'll be on here again tomorrow.

[zeno]

I dug out the manual for the cheep model
of that year. Same basic design but lacking features
like comb filter, jack pack, better audio etc.

Start process.
Relay closes, applies 150 VDC to HOT & that little board.
The little board has a multivibrator that drives the HOT base.
This gives some HV.
A winding on the flyback ( FBT ) is rectified by CR3473 &
gives 25 volts to the hoz drivers.
Also goes through R3464 12 ohm 10 W to Q3437 the 12V regulator.
As the 12 V comes up it starts the hoz osc & the set
is in the run state.
If any of the chain breaks that 2 K resistor usually will burn.

Like most sets this one has two grounds for measuring DC.
HOT GROUND used for HOT & multivibrator. Use the anode
of CR3205 on HV board for measurements.
COLD GROUND use the CRT ground or IF shield for measurements.
This is for almost all other DC grounds.

For now check for 150 VDC at C of HOT using the hot ground.
Then turn off set, wait a few minutes, hang the meter on cathode
of CR3473 & cold ground. Turn on WHILE WATCHING meter.
It will either go up & stay up, never go up, or go up then
quickly down.

73 Zeno