its about the very 1st 3/4 in a very straight vertical purple edge. Since its on the edge its only show about 6" beyond that on the top and bottom the crt curves and it does not show. The purple is straight that is, it does not curve with the tube.

Tried deqaussing, no help. I tried taking a pic put it is too faint to show up.

It also seems the width is underscanning as the screen seems to blank out at the extreme left edge, maybe the 1st 1/4 inch from the extreme left, the the purplish hue for the next 3/4 the fine. You can see the picture thru the purple hue.

turned the camera on its side and got a close up. this is a B&W, the blue screen is not right, its grey, not sure why the camera is having such a hard time, but you can see the dark area and then the purple

another

opps that was a dupe here is another,

If you adjust the horizontal centering, does the purple shading follow the raster/picture?

How's your HOT and cathode current doing? If you adjust the centering and the shading stays, it's a purity issue.

had not even thought about a purity issue since it was such a nice straight line. I did check the purity on the red screen (just turned down the blue and green drives) with the Heathkit sig gen in the purity mode. guess I should have checked the green since its lacking that for the purple.

Its like the green gun is getting blanked at the very begining of the sweep.

I vote that it's a mild horizontal drive problem causing a ghost foldover, and definitely a horizontal problem of some sort. I strongly doubt purity, although I suppose that's possible if the purity rings and yoke are set really weird.

Charles

horz drive alright, just had the bias set too low, the reduced scan size must have been unequal on the guns, it was under scanning on all, just a bit more on the green. Better pic, and no purple.

it was underscanning on all guns you could see the black edge on all colors just a bit more black on the green.

I will check the anode voltage and HOT current to make sure its in the safe zone.

does it make since that the green gun would scan a bit less due to the contsruction of tube? I am thinking angles of deflection and electron gun placement.

the way it was setup there was under scanning and not over scanning.

cathode current is about 250-260 should be 220 per the schmatic. that is just enough bias to get the full scan. brightness at normal levels.
reducing to low bright low contract gets it down to about 245ma.

low brighness if fine for viewing now. Before it would completly cut off.

High brigtness is good, more than needed now with adjustment.

there is a 5.6 ohm resistor in series with the horz yoke drive wire. I am going to check that to make sure it has not drifted causing too much of a voltage drop and resulting in a loss of scaning. there is also a 'centering" diode across the resistor, not sure what that is about.

Isn't the picture showing ringing symptoms? These are tricky to resolve sometimes. I like to start by completely removing the video to carefully examine a blank raster for uniform luminance. The reason for this is that sometimes periodic luminance variations can get into the video signal -- sort of like barkhausen. If the the blank raster displays the problem then it's a ringing issue in the horizontal sweep stage. If that's the case I'd start with a fresh set of tubes to rule out any quirky stuff like "pinked" grids, neutralization problems, cathode leakage etc. If the ringing is still present after a fresh set of known working tubes then it's either a supply voltage issue or a bad component. Start with checking supply voltages. You may need an oscilloscope to verify the DC voltages are "clean" - no hidden noise. Make sure the scope has a timebase that has variable delay so you can "step" through each scanned line in the picture. Barring any of this being the culprit ... reflecting on the problem reminds me that ringing simply means the energy of the flyback is not being released uniformily during the 15.3 us sweep interval (time it takes the electron beam to move from the left side of the picture tube to the right). So, it could be a non-uniform drive waveform or it may be an impedance mismatch between flyback and yoke. Well ....there are many possibilities. That's the nice part about trouble shooting old color TVs. It makes you think a bit. :D

make sure all your filter caps are up to snuff. Ac leakage can cause similar problems

filter caps seem ok (based on ripple on scope)

still having problem with getting a full horz scan. I checked the HV with the crt bias fully CCW to have zero beam current (I assume that is how to have zero beam current, crt was dark) checked HV was right at 30kv. Schematic says should be 26k max, so I adj horz bias to get back to 26kv. adj CRT bias to get normal CRT brightness back, and now short on horz deflection again.

argh..

there was not 5.6k resistor in the yoke path, AND the Flyback has a trim pot inside the HV cage that has an access hole on the side of of the cage. This is NOT in the schematic and there is no marking on the cage saying what it is for.

I am wondering if it could be a horz width control.

This purpish line is def related to scan width, when I change the format on the converter box to a smaller view (margins on all sides of the programming) there is no issue with the purple in the image, only when the image extends the the end of the scan does it show up. the green is just not scanning quite as far as the blue and red guns. If I could get it to do the normal amount of over scan the issue would be gone.

Seems odd that you have to rely on the HV to be set over max to get the correct scan.

I am going to monitor that HOT current and try adj that pot in the cage to see what it does. Noting the starting point of course.

I have a packard bell thats doing the exact same thing. I have come to the conclusion the flyback is bad because of the high cathode current and everything else checks ok. The flyback gets so hot after about 45 minutes its soft and melty sticky to the touch.

40 ma doesnt seem like that much but at 400 volts or whatever the b+ is it equals some serious wattage and heat to something that really cant get rid of it.

My symptoms are, purplish on the left side, high cathode current and overheated flyback. The anode voltage is fine, it does drop a tad at max brightness and the picture pulls in a little.
The new flyback is sitting in the box on top the set. Maybe this thread will help motivate me and get it together.

A bad flyback could be it. Some shorted turns or leakage could cause an impedance mismatch with the yoke resulting in ringing.

going to try adj the purity and see if I can move the yoke a bit more forward to increase the scan with out having to increase the drive.

Have not check the temp of the fly but will after the next test cycle.

the pot in the HV cage was a horz centering pot, so I adj that and re did the purity (rings and yoke placement).

I am getting pretty much a full raster now, I could get more by upping the horz bias, but as is its about 240ma with the CRT bias at min.

Still have a bit of center RG vert issues top and bottom that I can't seem to work out with the convergence board.

I am going to try replacing the Se 4pack with discreet diodes and check again.

I checked the Se pack and was getting AC on them (and DC) so my guess is they are leaking when reverse biased. I assume this is not good for convergence.

At least the purple line is gone.

while doing convergence I had some issues wiht the RG vertcenter topa nd bottom.

checked the Se 4 pack and one was bad. Also a bad resistor off the diode was 250 shb 56

got the diode pack replaced, replace a 4X out of spec resistor on the conv board. Just got to find my diddle stick to finish the convergence on the right side.

Fly it running pretty darn hot So maybe that is the issue with the lack of scan width.

I turned down the horz bias so the cathode current would be lower and got the purple line back. Oh well. Just have to use it for short periods of time I guess unless I can find a philco fly (assuming that is the problem).

I have a secore model SS105 sweep circuit trouble shooter, but I have no manual and have no idea if it would work with this set (has an octal plug, the set I have uses the 6KD6 which seems to new for this tester.

Next plan will be to check the "focus" adj. Its a coil that is tied into the horz winding of the yoke, you adj the focus by adj this coil. So the plan will be to check the cathode current and see if that coil has any effect. I will deal with the focus afterward. It uses a stick rectifier, so perhaps that could be an issue, that ady the focus coil is just overcoming, at the expense of excessive cathode current. Just speculating at this point. I need to check the drive waveforms and voltages in the horz drive circuits.

Maybe I missed it somewhere, but what make of set is this again?

its a philco roundie hybrid, has a SS tuner and IF, all the rest is tube.

there is no adj for horz width which seems to be the problem, the under scanning of the horz results in a raster that just fall short of full screen, with the green gun on the left falling short a bit more that the red and blue, resulting in the purple edge on the left.

I can adj the horz bias (there is a pot for that) enough in fill out the screen and get rid of the purple edge, but then the cathode current soars to over 300ma, and the KV is at 30kv.

I have to check the drive waveforms and peaks on the horz out tube grid, but its getting old. Its such a low parts count circuit, I am tempted to just shot gun the entire board.

I am going to be check the B+ more closely, starting with the current draw at the B+. Its a bit of a pain since the bridge diodes are directly soldered to the 1st filter cap (this is where the schematic wants you to check the current draw). So I will need ot un solder some very well wrapped diodes. I will prob just snip them out and replace with some 1n4007's.

http://www.videokarma.org/showthread.php?t=247179


this is the set

Did you try rotating in different HO and damper tubes? My CTC-5 had a width problem, turned out to be a HO tube that was OK on the tube checker but obviously not good enough in the set. Checking the H drive is also a good idea, as you said.

I did, but will try a few more. will also sub the driver tube a 6BL8

Is this color 'fringing'? I just got a hold of a suplement from Mark (zenithfan) for my CTC-9 that mentions purple fringes being a result of unequal cathode potenials, so if 2 of your cathodes are tied together while the third is off a resistor by itself at the video amp tube it might be worthwhile to look at.

Is this color 'fringing'? I just got a hold of a suplement from Mark (zenithfan) for my CTC-9 that mentions purple fringes being a result of unequal cathode potenials, so if 2 of your cathodes are tied together while the third is off a resistor by itself at the video amp tube it might be worthwhile to look at.

Fringing due to unequal cathode potential would be expected on small bright highlights anywhere in the picture, I think - so don't go there until the scan problems (and possible edge convergence as well) are fixed.

swapped out some horz tubes (hot and driver) minor change. there were a couple out of spec resisotors the screen on the hot had a 47 that was 60+. it was in series with a 7 watt 4200ohm resistor. I am guessing the 47 was there to measure voltage drop to determine current since it gives a screen ma of 21 in the sams.

there was one cap that came off a winding from the fly that connected to the horz bias adj (which is a pot that goes to the HOT grid). I dont recall checking that cap.

there were a couple other 5% resistors that were out 20% again in the grid circuit of the HOT. the coupling cap from the horz osc to the HOT is a .0047 but its a disc so I really doubt its a problem, but again, I may just shot gun the parts in the horz circuit when I pull the chassis. I will leave the 5% caps (the clear tube ones) in the horz osc tank circuit since the horz freq seems fine. Will just replace the screen and cathode bypass caps.

there is a VDR in the bias circuit off the fly, but it has no specs so I cant check it. I assume this is used in the HV regulation, there is no shunt tube.

replaced a few out of spec resistors (not far but 20% on a 5% rated).

and a few disc caps in the horz osc circuit (mainly the coupling cap to the HOT). these disc tested "funny" on my cap tester, the eye would not open all the way and the edges were fuzzy, more so than what I have seen on other caps. I replaced with some good quality film caps, that were higher rated voltage.

There was a 23pf 1kv on the damper plate to ground, just since I had the chassis out I replaced that one as well.

no effect at all, at least it still works.

Still under scanning.

The adj calls for zero beam current, adj horz bias for 25.3kv.

Not sure how to get to zero beam current, what I have been doing is turning brightness all the way down, screen drives all the way down, and CRT bias all the way down to get as dark a screen as possilbe. With the Horz bias turned fully CW I can get the cathode current to 220ma which is in line with the sams. I am reading this with a simpson 260 bypassed with a .1uf cap.

when I turn up the brightness to a normal viewing setting (screen up and crt bias up) the cathode current goes up to about 320ma max (it varies with the signal).

that just seems high to me. AND I still lack full horz sweep.

voltage reading look good now that I am using my VTVM, the DMM was just not giving me good readings. There is a 4200 ohm 2watt resistor in the yoke (Y-107) but I cant imagine that being an issue.

Next up will be the drived voltages to the HOT on the scope.

I read somewhere that you need to make sure your equip is accurate, well the VTVM was way off, I adj the calibraion.

I get about -40v on the HOT grid, should be -60 (yes it was that far off).

My B+ voltages are off some but no more than 10 on the various B+ amounts.

Considering that it should be able to fill out the raster at 110 and its short at 120 makes me feel its GOT to be the horz drive.

I have tried mucho HOTs all about the same all NOS.

So after much fiddling I will get the scope out, set it up (have to set the voltage so I can measure the P to P) and see whats going on.

IF the grid drive is weak I will have to see why. I have tried half a dozen horz osc tubes, replaced all the coupling and bypass caps, and any out of spec resistors. The voltages all look right. the only thing I am not clear on is a 18k and 680pf 5% resistor in series that come off the plate of the horz osc. I assume this is some kind of wave shaping network.

FIXED, AND i AM AN IDIOT


after consulting with some folks over at fun with tubes, I check the line voltage AT THE CHASSIS, turns out it was low, I still had the set on the variac and thought I had 117v at the chassis, wrong, voltage drop across the line/switch must have been doing me in.

The orig problem of under scan was prob fixed when I replaced the osc driver tube, as this improved the scan width, but by then I had the set on the variac.

added some "active cooling" as a precaution on the fly, will monitor its effect on overall temps.

Not so fast. the concern for the hot fly had me recheck the HOT grid voltage, should be -60 was -40

I scoped it, 120v pp correct waveform, but should be 190vpp

checked the osc tube all forms and PP looks good on that tube.

on the osc tube a 6BL8 screen volts look good cathode voltage looks good so short of a bad tube I cant see why the wave form would be down (but I will try subbing some tubes to see the effect anyway).

I am going to check the wave shap network cap, its a 680pf tube precision cap, comes off a resistor that is at the plate of the osc tube. If leaky I assume it could drag down the output.

I subed some other tubes (all test good on my hickok 533) for the horz osc, best I could get was 140pp. Low drive would sure explain the hot flyback and the fact that I have to turn the horz out bias all the way down to get the cathode current in check.

I have a local tube guy I may go to his place and check a bunch of nos 6BL8's and pick the strongest he can find (if the 680pf is ok).

hmmm lifted one leg of the horz wave form shaper network, very leaky and would not even open the eye of the cap tester at all. going to remove it completely and check again. This could be the answer i hope.

oh well once I got it completly out it was fine. turns out having the oscope attached to the TV was causing the bad cap reading with one leg lifted.

I recheck my oscop calibration, my grid drive to the horz osc tube is low 100v should be 170v so I will be looking into the feed back loop on that next.

Check all the resistors going from the horiz osc sectionto the HOT. My CTC-9 had drifted vaules there, leading to a low drive waveform. If also had fixed drive, but I'm installing an adjustable circuit right now.

Got it. My problem was not a problem at all. after changing out the horz osc tube and a few other componets it was looking good. but my scope indicated low HOT drive. Turns out I had setup the scope wrong, all was good.

I am calling this one done, I will be adding the squirrel cage blowr on the HV tower top and butting it up.

after a longer viewing time I went to adj the focus, the plastic adj piece was very loose in the bore of the coil. I had noted before that when cold the focus is frozen, after a few min the adj loosens up and feel normal now when hot it practically falls out.

the Horz defection coil blue lead it tied to this coil.... hmmmm

I checked the resistance, 1.6 ohm should be 30. now this is with it in circuit, but I see nothing across it that would reduce the resistance but for a 100k resistor so unless that is shorted I would not expect to see this.

I have a new coil on order. Perhaps this will finally address the underscan, yes I got it to fill out the screen by careful adj of the centering control and careful selecting of horz tubes, but I think it should not be this critical, so perhaps a shorted coil would result in an impedance mismatch in the horz circuit that could put a drag on the fly. I check the waveform and PP on some other stuff like the horz blanking signal which comes off this coil, it was way down from spec too like 40% low.

dumb me did not see that the focus coil was across a fly winding, after taking it out of circuit it checked fine. Darn... i will try a new one anyway since this one is all gummed up with a waxy stuff that make the adj gooey.

I also set up the chassis to do a B+ current check. I may end up putting a fuse on the B+ as well. esp since I still have the orig filter caps (they check like new for leakage and capacity so I just can bring myself to restuff them)

I did not check EVERY section of the two caps so if the B+ show excessive draw I will do. I know that if the B+ is low that would explain my width issues so that is the main reason I am checking. Overall the B+ is not that far off so I dont think I will find anything major here.

I did run a fan on the fly and after 1 hour it was barely warm so I will def be looking into how to set that up on a perm basis. It was pretty noisey so I will be looking for a smaller quieter fan. I want to make the fan install a no mod to the HV cage. I am thinking of making a plenum that will adapt to a partially open cage top. it will take a bit but I really like keeping that fly cool.

I wonder if the flyback has COPD, ED, BPH or leaky prostate syndrome causing the current to be a tad high.
Do you think there may be a chance the fan will suck stray electrons out and cause someone radiation poisoning?

well the B+ went just of the 500ma scale with no signal (full raster), with a signal it dropped down to about 480-500ma depending on the scene.

the sams call out 460ma with no signal so its a little high.

I will prob end up stuffing all the caps just to be sure.

I should have let it run for a while to see if it went higher or lower. The cans to get pretty warm but they sit right next to the power tranny and one of them has a big sand resistor on the bottom soldered to the terminals.

got a new yoke on the way, figure it cant hurt to try it.

went ahead and installed the new focus coil, improvement, will play with it some more. Have another focus coil to try later. The problem is these are alternate PN coils so I want to try them both and see which works the best.

got the new focus coil in it. maybe better but still I think its a bit under scanning. The focus coil seemed to help a bit with the cathode current on the HOT and "maybe" the scan.

I have a new yoke (the triad) but am just a bit burned out on this one. the pic looks real nice, color wise. The focus seems a touch soft (I have the focus coil slug all the way in, it effects the focus but does not seem to peak).

I did replace the focus rectifier just in case, no change. Overall the pic is very very good, and I am tired of fooling with it.

I double checked the filter caps, they test like new so I will leave them be.

I did add the B+ fuse a 750ma (normal current is about 450-500ma) so if the filters ever do short out the tranny will not have to wait for the main circuit breaker. the fuse is in one of those in line jobes, properly strain reliefed of course. The HOT cathode fuse is a micro fuse that has a neat holed soldered directly to the jumper term strip, mounted on top of the chassis, VERY easy to pop the fuse and check the current. I soldered in a .1uf cap across the fuse holder so you dont even have to bypass when checking. I thas a 310ma fuse, cathode current is right around 220-240 depending on beam current.

I still plan to buile a plenum to fit in the cage and direct air from two micro fans (the kind on cpu's). I need two as they dont move much air. The plenum will be made from cardboard and will direct the air to the main body of the fly. the intake will come from the back side of the fly, the cage door left open. the exit will be from the existing convection louvers. The fans run off
12vdc, I will prob just power them from a wallywart transformer. I am not going to do anything that cant be undone and returned to the stock configuration.

watching Kojak on it now :thmbsp:

Run your 12vdc PC fans on 5 volts. They will slow down and be quiet while still keeping the fly cool. Most PCs vary the voltage depending on heat load so they dont sound like a jet all the time.

You could also use the rectify and filter the 6 volt filament supply for the fans.

still not satisfied.

I chaged the pic format, so there would be a margin all around the pic (cant recall which format but it was on the convert box).

in this smaller format I could see the pic was clearly not centered, so I centered with the horz centering pot.

switched back and now I have the dark bar on the extreme left edge.

Now the Raster is fine (full screen) its just the pic that causes the dark vert bar on the left.

I did some more reading and I am back to looking at blanking. There is a triode section of a 6GH8 that takes a pulse a the grid, and is coupled from the plate to the cathode of the chorma driver tubes.

IF for some reason the tubes were cut off too long I assume this is what it would look like.

But there is just not a lot of parts involved, so I will be checking them AGAIN and doing some tube rolling.

I guess I could compare the CRT grid voltages to the composits video signal on my dual trace scope and see if they line up.

I threw my net over on ARF and fun with tubes to see if any one else has some input on this dog.

Just for fun I am going to try the one OTA transmission on UHF and see how it looks. the problem is its such a weak station that the pic is awful.

I am just try to eliminate the converter box as an issue (it works fine on other tv's).