|
|
|
#61
12-13-2009, 06:58 PM
|
|||
|
|||
|
more fiddling, I had the width control set to much, backed it down and then readjusted the horz control pot and then the horz freq slug and now it looks like the horz lineairity is much better. So I will try the other set, but on that one I will try increasing the horz width since it had the reverse problem. Lot to learn working on these old sets.
Dumb mistake, I inserted the slug adj tool in the wrong slug (duh) when attempting to adj horz freq. It was one of the peaking coils I think. anyway it seems to effect the sharpness of the pic and the sound so I played with it and have it back to where I was (at least as best as I can tell). Rookie mistake. 
|
|
#62
12-13-2009, 08:09 PM
|
||||
|
||||
|
Dave, give us some pics to look at!!!
These dots you speak of... could they be interference from your source? I've had dots on the screen of old sets that turned out to be interference from DVD players. More recently, my daily watcher in the living room gets weird dots/lines in the picture when the coaxial cable from the satellite receiever takes a certain route behind the set. The sat receiver is a good distance from the TV set, however if the wire is in a certain area, it will throw some interference on the screen. It's not bad, but annoying. Reach back there and move the wire to another position and it goes away. At first, I thought the wire itself was bad... tried another... same affect. I would not have suspected this at first being that the wire is shielded. Although not as likely, but still a possibility is interference from something else in the home. My front porch light is on a dimmer. When the light is on (whether full blast or dimmed down), it causes lines on my TV and puts a loud buzz in AM radios. I can walk up to 200 feet away with an AM radio in hand before the buzz goes away. The lines going across the TV screen seem to travel up the screen for a while, then slow down and go the other way. Oddly enough, I don't notice them on my Diamond D, but they are very much there on a SS Curtis Mathes. All this trouble caused by a dimmer switch.
__________________
Charlie Trahan He who dies with the most toys still dies.
|
|
#63
12-14-2009, 12:44 PM
|
|||
|
|||
|
I will get some soon my camera is MIA right now (kids). Darn horz lineairity is acting up again, left side opens ups. I think I will try a tube swap ONE MORE TIME, then I will a carpet bombing replacement of every cap/res in the sweep board. I will try a diff yoke just to be sure.
|
|
#65
12-15-2009, 03:51 PM
|
|||
|
|||
|
if you look close you will see the left corner drooping down. On the cross hatch the vertical lines also sweep to the left at the top, about the 1st couple inches.
on the close up of carol you can see the courseness of the pic, due to the poor interlace. I can fiddle with the vert, minute adj will temp correct the interlace but it jumps right back after just a second. The horz wave is from the input to the HOT, it has a little defect in the very begining, but I noticed that on another set that looks ok, so I do not think that is the issue. Since the shape looks good going into the HOT I have to assume its in the HOT/FLY that the problem exist. I tried a different yoke, same result. The Horz lineairity is not a huge problem, cant even notice it unless I pull up a graphic with a lot of staight lines (like that program guide). the interlace is a bigger problem. lastly is the dot crawl, I will attach a pic of that
|
| Audiokarma |
|
#67
12-15-2009, 06:08 PM
|
||||
|
||||
|
Does the dot crawl only stay at the very top? How far beyond the mask does the picture go? If you have the picture spread only to the edge, you're bound to find stuff there. The picture should go at least a half inch beyond the mask.
Are there any caps/resistors left in the verticle section that you haven't changed? Does this set use one of the combination components in the verticle section? If so, maybe you need to build a new one. I figure you've already done this, but I'll mention it anyway... cleaning the verticle pot with some spray?
__________________
Charlie Trahan He who dies with the most toys still dies.
|
|
#68
12-15-2009, 07:36 PM
|
|||
|
|||
|
response to Charlie
Quote:
|
|
#69
12-15-2009, 07:43 PM
|
||||
|
||||
|
Dave, that dot crawl lots A LOT like what my sets get when my front porch light is on (recall I mentioned having a dimmer switch on it) and mine goes through out the picture as well... the dots move horizontally across the screen, and the whole pattern moves verticle somewhat slowly. Not saying your front porch light is the problem (wouldn't that be freaky), but sounds like something external.
I would not suspect the disc caps, but that combo component would get one of those funny "raised eyebrow" looks that Mr Spock gives. 
__________________
Charlie Trahan He who dies with the most toys still dies.
|
|
#70
12-15-2009, 10:11 PM
|
|||
|
|||
|
I will keep after it.
Did some more checks, this time on the AFC diode pack. the center (which is the feedback from the horz yoke, was right on spec for form and amplitude (15v pp) however the sync pulse was off amplitude (both sides of the diodes from the horz intgrater) at only 5v PP correct form though... I checked another set, same deal , center of horz AFC diode pack 15v PP other side of diode were both 5v pp but good form. the AFC lock seems fine so I will just chalk it up to an error in the sams (for now). hmmm I did not think to check the contrast level, guess that could cause a lower video signal to be sent to the sync sep and therefore a lower sync pulse amplitude (if I am reading the schmatic right) I still have a LOT to learn. I am also looking for noise on the vert sync pulse still that could be causing the interlace issue, will have to give that a go tomorrow.
|
| Audiokarma |
|
#71
12-15-2009, 10:56 PM
|
||||
|
||||
|
It almost looks like tuner RF interference.. Check your 75ohm coax and make sure you have good grounds and no interference betwween that and any power cords or something in the line that would cause interference. Just a hunch. Back in the day when we had analog, I remember watching a VCR tape or playin Nintendo on my old CTC-38 and when it was set to channel 3, our KCRA channel 3 would bleed into like RF interference just like what I se in the pic. Color TV's seem to filter this as a crawl not so dot like.. B&W sets seemed to filter it in dots.. Nonethe less if I switched to channel 4, problem gone. And remember, you are supplying a very strong signal to the tuner.
__________________
Honey, turn on the tv.. I'm cold!
|
|
#72
12-16-2009, 11:19 AM
|
|||
|
|||
|
well beed doing some more reading, going to try yet another Damper, also going to check the grounds of the vert hold pot. Read somewhere that if that ground get even sllightly bad issues pop up, esp with it sitting right next to the horz (this is for the bend it the pic on the left side).
played with the contrast no real effect on the amplitude of the sync pulse oh well so much for that. The only ohter thing in the path is that horz integrater. thats one I plan to rebuild just for grins. actually the odd thing was the sync pulse got a little stronger when the contract was turned down. I may just break down and replace ever single cap and resistor on the sweep board. Not many really.
|
|
#73
12-16-2009, 09:01 PM
|
|||
|
|||
|
two new damper tubes were tried.. no change.
put on the cross hatch generator, hmmmm the horz lines look fine. the vertical get a little messed up at the top, but if I turn down the RF on the gen they get better. I dont get why the horz lines look fine from the gen but the horz lines on the OTA program guide bend down on the bottom left edge. Put a indian head test pattern on it, not very good, this this is a pita to get looking right.
|
|
#74
12-28-2009, 05:15 PM
|
|||
|
|||
|
Back on the interlace/horz linearity (since my emerson idea got squashed today) I bought a bunch of caps, the plan is to pretty much redo the entire sweep board including some HV caps on the flyback/damper/HOT. there are a few 3kv and 5kv in there. I also ordered a bunch of 800 pf decoupler caps for the IF board, just in case something is going on there. The interlace issue is a bugger, more than anything else since it kills the resolution.
I would like to get this one done so I can move it into a bedroom and make room in the garage for another project TV. The current rule is I have to be able to put BOTH vehicals in (Explorer and Suburban) AND you must be able to get in them with out having to pull one out 1st. I still want to get a Maggie astro roundie color up in TN, that is a biggie.
|
|
#75
03-19-2010, 03:00 PM
|
|||
|
|||
|
ok back to this one.
Pulled the chassis, while I had it out I decided to clean the tuner, I noticed the gear the turns the little tuning slugs was stripped. I had a junked tuner so I was able to replace that gear. Cleaned the turret buttons with an eraser and them lubed them back up with some tuner cleaner/lube. I am going to replace some more caps on the deflection board and on the damper tube. I scoped the grid of the vert osc last night and it def has a lot of Horz noise getting in there (when compared to the other set with the same chassis). Not sure exactly how its getting in, lead dress looks good. I am hoping by replacing the remaining caps I will just get lucky. Its just too darn hard pulling this chassis and PCB work is easy so I figured might as well. there are not a lot of cap anyway. I dont like the way the vert hold pot ground is shared with the horz hold pot but it works on the other set... Anyway will get back on it tonight.
|
| Audiokarma |
 |
|
|
Linear Mode
