another zenith combo

[holmesuser01]

Unless a set has hit the floor, I've only seen one or two sets that had bent shadow masks.

I used to love hearing the description of the problem when a customer would bring in a set with a burned up degaussing circuit.

The words FIRE, and SMOKE, and STENCH were used often.

[DaveWM]

I have been fighting with some minor pic problems, tends to bloom a bit go out of focus on some scenes. check the HV again, 26kv with pic, but jumps around a lot with brightness (beam currrent on crt). when set to the setup mode the HV is 27kv and will not go lower (that is with it turned all the way down).

I have been down this road before, on my last zenith with the pulse type regulator (6HS5). That one required a new VDR and a factory mod to the HV control pot to get under control.

also while watching I noticed the reds start to fade to pink and get splothcy.

the darn purity ring assy is very loose, some how I must have moved it. I found it when I checked the setup (after checking the crt). Oh well at least I am getting a bit faster at finding the problem.

[DaveWM]

took a break from the TV for a bit to concentrate on the SS stereo. pots needed some cleaning. AM was not working right. It was very odd, would birdy and could be made to work if I turned it off and then on and carefully manipulated the selector. had some odd voltages in the AM section. Noticed I could kill it by touching the VC (the midde section for the RF tuned section, not the osc and not the main tuning from the antenna coil). it would stop and would only play if you turned it off and then on again. I finally swapped out the RF amp transistor and bingo, works fine. The RF amp transistor had leakage between the E and C and had the wrong v reading in the diode mode between one of the leads to the base. Anyway its working well now, I check the stereo separation, all good, so it will go back in now. I will be turning my attention back to the HV regulation next. I noted some odd bends in the vert color bars I was getting OTA, the right side bars were not straight. guessing someting in the horz sweep. I will check caps around there esp the coupling caps, and mess with the horz osc/horz out to see if I can get it working, but I need the get the HV regulation working 1st.

[DaveWM]

wondering about how tight the zener diode should hold the voltage, it says 11.5v on the schematic, I get 12.6 at the zener.

[DaveWM]

back to the tv, 23XC36, full raster, but the pic loses about 1 inch from the left side. Its kind of a soft black edge, I am new to this but think I read up on blanking issues. The right side is not a problem. I am going to check the two blanking diodes that connect to the grid of the vertical amp. There is also some streaking in the pic, I need to tap around there but again I am thinking the video driver transistor or more likely the vert amp tube. I am not sure how to check or even test for defective blanking if that is what this is. I dont think its horizonal centering as I assume that would effect the raster. the horz hold adj did not move it at all. I dont recall seeing this when I first got the set, but perhaps I just did not look it over close.

I still need to pull the chassis to go over the HV reg parts and will prob replace the 1kv caps (tube type).

for the streaking I was planning on putting up a test pattern and checking with a scope starting at plate of the video out tube and working my way back, looking for noise. will prob just sub in a new video out tube 1st and hope for the best.

anybody work on one with the loss of pic from the extreme left edge?

[old_coot88]

Originally Posted by DaveWM

...anybody work on one with the loss of pic from the extreme left edge?

Is the raster itself pulling in? Or is there a black bar in the raster? If the former, it can be due to excess HV (the reverse of 'blooming' from low HV). Bill(oc)

[DaveWM]

raster is fine, just when a signal is present the pic pull in from the left about 1 inch, I will get a pic later. I will also try an OTA signal (there are still a few low power uhf stations nearby) just to make sure my converter box is not the problem.