B&K 1076 TV analyst - Page 3 - Videokarma.org TV - Video

DaveWM · #1 04-08-2010, 12:02 PM

I am going to leave them be, not sure about how those pins work that hold them in. I have a solder sucker iron that works great on PCB.

I hope to stuff the 3 section can tonight. I figure no hurry on replacing that NP cap since I just want to see if I can get it up and running thru the RF output anyway.

DaveWM · #2 04-08-2010, 04:25 PM

Banderson, can you confirm the value of C9a/b. Per the schematic it is a 50/50mfd both at 150v.

It should be a can on the bottom of the set on the left side looking at it from the bottom, closest to the power tranny. Mine was switched out.

DaveWM · #3 04-08-2010, 04:28 PM

oh and confirm the can is a common POSITIVE!

bandersen · #4 04-08-2010, 04:56 PM

Sorry, I have a couple 1077s which are a bit different. C9 is a 0.047 uF cap to the yoke test signal output. Mine do have a couple 10uF and a 20uF with positive to ground. They are for filtering the B- supply.

DaveWM · #5 04-08-2010, 05:18 PM

anybody else with a 1076 let me know. the bias cap (I think) in mine does not match up with my schematic. I just dont trust it since it does not look orig (the cap).

The 330 resistor comes off the bias supply diode to a 10uf section of the cap.

then a 3.3k resistor goes from that point to the second section a 50uf. This section is tied to the 3rd section a 20uf (so 70uf total).

from the 70uf total junction it goes to the V1 photo multilplier tube (blk stripe), and to 33k power resistor on a term strip (brw stripe). Che can is connected to a term strip that is rivuted to the chassis (not solderd just rivut). Per the can its a 50/20/10 350v on all POS can.

DaveWM · #6 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 · #7 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 · #8 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 · #9 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 · #10 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 · #11 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 · #12 04-09-2010, 09:45 PM

Cool - I like that purple glow

Good luck tomorrow.

DaveWM · #13 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 · #14 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 · #15 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.