Sylvania 336mu

[sylvania]

yes that resistor tested good with set off after power applied for a few minutes the resistor was open.I never had that happen before. I thought once it was open it stayed but this one acts like a current limiter in reverse. Now have to trouble shoot high voltage and interference with sound. I replaced that resistor and voltages returned to near the specs shown in the Sams. Doyou think that resistor would of taken out both damper tubes and a horz output tube? They tested good before this happened picture was dim, then high voltage quit, I found those tubes showing bad.

[DaveWM]

without a full schematic its hard to say if a defect in the 125v supply from the stacked b+ was used somewhere in the horz sweep circuit.

So you replaced the 68 ohm resistor in the cathode circuit of the audio out and all the voltage are reading correct for the audio out tube now?

Loss of HV generally starts with subbing new tube, horz osc, horz out, damper, and HV rectifier, and if used HV regulator.

I prefer tube subbing over tube testers, esp in sweep circuits.

I generally will uses a my BK 1076 analyst next to start with a plate drive signal to clear the damper/yoke/fly, if that works then I move to the grid drive signal, that will check the horz out tube, if that works then move on to the horz osc tube and check for voltages at the plate and screens.

[sylvania]

Dave, thanks that is what i will do, thought it was strange that I had three tubes go bad all at the same time, Yes my voltages are with in 20% of Sams specs on that tube.

[sylvania]

I was checking the chassis voltages and the high voltage shut down, the damper tubes 6V3A, Horz Output tubes 6BQ6 filaments are on. The HV rectifier tubes (2) 1G3GT filaments are not . Could this be fly failure and what is the safest way to check tubes in the HV cage without damage to a circuit or myself?

[DaveWM]

tape a neon light to a plastic straw, hold it near the plate lead of the horz out, it should light up when near (1/2") same with fly, anywhere near the fly and it should light up.

[sylvania]

give it a try

[sylvania]

I took off the cap to the HV rectifier tubes and removed them, checked the dc voltage from the fly I am measuring 400v. Both tubes not working (1B3GT) have checked other voltages all tests normal so far. Still no HV to anode lead.

[sylvania]

If anyone out there would like to know, here is up date. checking thru this chassis again found the regulator tube 40B4 filament burned out. Waiting on replacement and see if that was the problem.

[sylvania]

I finally have this set working, but I can not get picture to fill out screen on right side as seen in picture and it seems the picture is not as sharp as it could be, I have the picture pot adjustment maxed out ,adjusting the the picture pot I run out of adjustment.

[sylvania]

Anyone know if the Halolight florescent tube can be removed from the front of a wood cabinet with out having to remove the CRT? I have a book showing one removal, but it only shows it being removed from a metal cabinet thru the front