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-   -   B&K 1076 TV analyst (http://www.videokarma.org/showthread.php?t=247448)

DaveWM 04-08-2010 05:40 PM

besides not being able to find this setup on the schematic i am concerned that it may not be orig to the unit based on bridging the two sections together. I figure if the factory wanted a two section cap it would have come that way.

DaveWM 04-08-2010 05:43 PM

of course the other problem is the schematic has a 9a/b pos can cap but I cant for the life of me find the b section on the schematic. I have already come across a miss marked cathode bypass cap (+ to ground) so my confidence in the schematic is not the highest.

bandersen 04-08-2010 06:00 PM

For what it's worth, here's the 1077 power supply schematic: http://www.bobandersen.com/images/B&...scan004001.jpg

It uses three separate caps for that bias supply.

DaveWM 04-08-2010 09:20 PM

I am just going to use a two section 10 and 70 uf and wire it the way it is. there are some other differences from the schematic, for one the schematic has two diodes in series, I assume for some kind of voltage drop across one of them. This one does not and it all looks original. May have something to do with the 3.3k resistor after the 330 ohm. Just going to assume it was working so will go with it.

DaveWM 04-09-2010 09:10 PM

whew done with the recap. only iffy thing is the dumb 10uf 450v caps are not clear on the negative.

they have cardboard on both ends (axial NSL brand), pinched on both ends.

Has a solid strip that has arrows in it pointing to one end. I am assuming this in negative since IIRC all modern caps ID the neg terminal.

I even scrapped one. Turned out the center of the cap was the negative. That threw me.

DaveWM 04-09-2010 09:12 PM

power up went well, about 500ma AC at 120v, no smoke, no issues. Nice purple raster came up. That is about the extent of testing tonight.

I will give it a rest and try hooking it up tomorrow to a TV.

bandersen 04-09-2010 09:45 PM

Cool - I like that purple glow :yes: Good luck tomorrow.

DaveWM 04-10-2010 03:30 PM

works, got a pic and tone. Now I need to try it out on a few different sets. The Emerson was ok, the predicta barely strong enough RF. I have a 80's era SS set I will try it on. I was not able to see a hammer on the sync pulse line at all on either set, the emerson had better lineairity (much) so not sure what is going on.

I have not checked ANY of the tubes so I will start with some of the RF out tubes to make sure they are ok. I am assuming there may need to be some adjustments as well due to the replacement of some caps on the Sweep board, but I will hold off on that until all else has been checked.

DaveWM 04-10-2010 06:11 PM

gonna need some work..

pic on the newer TV is pretty linear, but sync tears some at the top, RF needs to be turned up near full, horz adj is at one extreme, just barely locks, has a lot of snow.

color bars work ok, but not great, kinda washed out, and the adj seems to have minimal effect. RF output is only good on two of the channels.

The 1st thing I will try is cleaning the RF channel selector. I replaced several of the weak old tubes (12at7 and 12au7). I need to find a strong 6cb6, I think it is part of the RF. I replace it with a stronger tube and the pic went away. Put the orig back in. I dont know maybe its critical on the tuning.

My guess is the horz is just going to be an adj of a trimmer pot to bring the horz adj control back into center range.

The scanned image was also to big, and offset. This was the cas on 3 different sets. I will be doing some reading up on how that is adj. My guess is the CRT is under scanning, but that is just a guess.

I will need to check the voltages before going too far to make sure all is good on the B+. It uses a 6ca4 dual diode, that has not yet been checked.

DaveWM 04-10-2010 07:20 PM

cleaning the channel selector switch did wonders for getting the other channels working. But now I am getting some intermittent pie crust in the image, and shifting. Resolution is pretty good, I can see the scratches and dirt on the transparency.

Getting good video signal, I can see the bulleye gradients for contrast, and 325 lines on the vertical not as good on the horz.

old_tv_nut 04-10-2010 08:10 PM

Quote:

Originally Posted by DaveWM (Post 2970621)
I was not able to see a hammer on the sync pulse line at all on either set,

I would not expect a standard hammer pattern from this device - it's likely just a wide sync pulse for vertical. (not near a schematic to check at this time)

DaveWM 04-10-2010 08:30 PM

been messing a bit more with it, getting better, I need to do a good cleaning of the tube pins and the pots. I opened up the vert scan a bit (it was not lighting up the whole of the transparency). The RF antenuator is a little rough. Fun little device.

DaveWM 04-11-2010 01:51 PM

a bunch of very weak tubes. Next up is the color pot. it turns on and off but seems to have no effect other than the switch. I get bars but the pot does nothing.

DaveWM 04-14-2010 02:40 PM

Well I got the cap today, very pretty, almost too pretty to put in the tester.
Its a cross over cap, I am sure meant for the audiophiles out there.



Its pretty big, but not much different than what is in there (a little shorter and a little fatter).

After putting this in I will button it up and get to work on the transparencies.


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