B&K 1077 TV analyzer

[electra225]

Mine is kaput. Has no vertical deflection. I tested the vertical osc/output tube, a 13GF7 and it tested stone dead. I got a new RCA replacement, it, too, tests stone dead and it works just like the original tube did. No vertical deflection. I need two things now. One, to print out the schematic for the Analyzer and see can I find out what ails it. Second, to put that dad-blasted B&K 707 tester I have in the round file, on its way to the landfill. My Jackson 648 went on the blink, it should be done the same with. I have a TV-7, but it won't test Compactrons. I am in the market for a good working, "modern" accurate tube tester. I am sick of working with junk that lies to me. That is the second time in recent memory that tube tester had lied, causing me to chase my tail. I suspect that I have lost B+ for some reason to the 13GF7A. This will make an interesting project. The good news is that I have a spare vertical output tube if I ever need one......

[electra225]

I found that I have a real factory schematic for this instrument. I've watched a Shango YouTube video where he said that the vertical deflection portion of the deflection yoke tend to go open. I disconnected the wires for the vertical deflection coil and found it to check good. Next, I checked the primary and the secondary of the vertical output transformer, which also was found to be good. Shango also made a comment that operating an Analyzer with no vertical deflection can cause an unrepairable burn on the CRT, which will leave a black streak in the middle of the display, rendering the instrument useless. The CRT on mine is fine, so I am leaving the vertical deflection coil disconnected while I run some voltage tests. I am also going to disable the horizontal deflection by removing the anode wire from the high voltage rectifier. I should be able to run some voltage tests without worrying about high voltage running amok with no vertical deflection. Wish me luck.....

[TC Chris]

Is this device a dedicated oscilloscope for TV diagnosis?

Chris Campbell

[electra225]

The B&K 1077B TV analyzer is an instrument that generates all the signals found in monochrome and color TV receivers. It can be used to replace the missing signal or signals in a TV receiver as a diagnostic tool. Sound, color bars, IF, sync, vertical and horizontal pulses and voltages. It has 13 tubes plus a CRT that emits an ultra-violet ray that is shown to a photo tube that turns the image into an electrical signal fed to the TV under test. It was an expensive gizmo that a lot of TV repair shops used to some degree back in the tube receiver days. This particular model will also work on solid state sets.

https://antiqueradio.org/BK1077BTelevisionAnalyst.htm

[electra225]

I have found that the vertical oscillator is not running. The 13GF7A serves as the vertical oscillator and the vertical output tube. Pin 9 of the tube is the grid of the oscillator which should have -13 VDC on it. It has nothing. There are two transistors ahead of Pin 9, they have no voltage on them, either. I do have B+ on both sections of the tube. I'm running on by Variac and KAW. Draw is 104 watts at 116 VAC line voltage. There is a bunch of caps I haven't replaced and some resistors I need to check, located under the neck of the CRT. It will have to be removed not only to replace the caps, but to check the resistors. I'm getting 75 VDC decoupling boost voltage. I don't see a spec given for it. Anybody have an idea what it should be?

[electra225]

I'll need to remove the CRT to be certain, but, right now, the leading suspect is a .022 @ 400 VDC coupling cap that is very likely open. The voltage stops at this cap. This circuit is a bit unusual in that a tap off the PT provides grid bias for the vertical oscillator. I'm not sure I understand the operation of the circuit, but since the supply is AC, there is a diode in the circuit. I believe its job is to act as a rectifier for the grid bias voltage. I get 175 VDC at the point the voltage stops. There is a series of resistors in the circuit, so I'm sure bias voltage on the oscillator is lower than that. It gives -13 volts on the grid, but I'm not sure how that voltage is developed. I'm going to unsolder and remove the CRT then I can get under there to work better. I'll replace every cap, check every resistor and the transistors in the vertical circuit. If everything is good, I'd think it would work....

[electra225]

I worked on this thing all day today. It's better, but still not enough vertical deflection to fill the screen completely. The bottom one third of the screen doesn't give any response. Reading online about these things, about all that is left is that it has a shorted turn in the windings of the yoke. Element voltages are spot on, and the vertical oscillator is running now. It has served me well, but I believe we are at the end of the road.

100_1426.JPG[/attachment [attachment=2]100_1424.JPG

[William]

Greg, can it be used like that? Or, is it necessary to have a full screen to be of use? Don't give up, there still might be an answer.

Bill

[TC Chris]

Find a donor unit online for the yoke?

Chris Campbell

[electra225]

My guess is that if I need a yoke, it probably should be attached to a different instrument.....

The thing that has me thinking about having a shorted yoke is the bright white line at the bottom of the raster. Since that is an ultra-violet CRT, it shouldn't display a bright white line at all. Something is diverting the beam to one spot. Bill made a comment that will cause me to try one more thing, something I need to check to be finally sure. I don't really know how to check a yoke for shorted turns. Looking back at older photos, this thing has always had lazy vertical deflection, but was good enough to be able to use it.