I'm hoping to get some input on a horizontal issue I'm having on a Motorola TV with the TS-9B chassis; not sure of the model as the back cover is missing.

When it's cold, it is fine. After 5 minutes, ringing bars creep in from the right side and stop at the middle, accompanied by a decrease in width. Is this going to be a defect in the damper side or the horizontal output side? I'm leaning toward bad mica. All electrolytics and tubulars are new.

http://www.videokarma.org/attachment.php?attachmentid=184758&stc=1&d=1414954730

Try turing the set off for about 7 seconds, and back on. What behaviour does it show?

Turned off the set for 7 seconds, turned back on. Once the picture appears, the picture is momentarily fine, but ring bars reappear from the right side and quickly drift back toward the center over the span of 5 seconds.

Sounds like inter-electrode leakage/shorting in one of the horizontal tubes (Likely the damper or H out). Try subbing known good tubes from a working set, or NOS tubes if you don't have a set with those types.

I'll give it a try. Just looking for places to start that won't involve hauling the TV back into the shop, or hauling the 'scope to the house. :)

In the damper circuit, the doide is suppose to stop oscillations in the flyback after
the conduction pulse turns off the hv output tube.... So I would say your problem
lays in the damper circuit, possibly a cap in the cathode to ground area.... Or the tube
itself.... ? Odd I would think oscillations in something near the horiz deflection circuit
would effect the linearity of the lines.... But it seems to effect the brightness of the
lines.... Maybe the problem lay off the damper circuit feeding the blanking circuit....?

I'm sure you'll get it.... Looks like a good picture otherwise.... Wonder what happened to
that Toad soap....? I can't believe it didn't catch on....

.

When he did the '7 seconds off' test, the pic came in good at turn-on, stayed good briefly before the bars drifted back in.
Seems like if the fault were caused by a component other than a tube, the bars should be there instantly at turn-on.
Best WAG would be a gassy H out tube, 'specially since the width is affected also.

I honestly can't remember ever seeing a problem caused by a weak damper. All damper faults were either arcing or an open heater.

I hesitated writing that because of how the off-on test went. I have a book nicely detailing
the oscillations and how it may fault on the screen, and it matches this, so I posted it,
Since "hauling" the tv or scope to work on it sounds like it will be a chore..... Lets
hope it gets cured with a simple tube change..... Good Luck S-TV.

Heck, I bet he can just thump the tube with his finger and it may just make
those bars move around..... I'm pretty interested in this one, can't wait to see
how it works out....
.

When he did the '7 seconds off' test, the pic came in good at turn-on, stayed good briefly before the bars drifted back in.
Seems like if the fault were caused by a component other than a tube, the bars should be there instantly at turn-on.
Best WAG would be a gassy H out tube, 'specially since the width is affected also.

I honestly can't remember ever seeing a problem caused by a weak damper. All damper faults were either arcing or an open heater.

In the damper circuit, the doide is suppose to stop oscillations in the flyback after
the conduction pulse turns off the hv output tube.... So I would say your problem
lays in the damper circuit, possibly a cap in the cathode to ground area.... Or the tube
itself.... ? Odd I would think oscillations in something near the horiz deflection circuit
would effect the linearity of the lines.... But it seems to effect the brightness of the
lines.... Maybe the problem lay off the damper circuit feeding the blanking circuit....?

Okay, I've changed the H-out, damper and oscillator tubes with no improvement. The 'squeeze' is also affecting horizontal linearity, like a ripple, but takes a close look to see it. When something moves across the screen I can really tell. You are confirming my suspicion that this is a damper-related defect. Going to try seeing if there are any micas or ceramics around the damper... ETV has the TS9B print on their web site so I'll take a peek prior.

Wonder what happened to
that Toad soap....? I can't believe it didn't catch on....


Apparently $1.99 for a box of Toad on sale was still a bit much for a detergent that left your clothes fresh as a swamp lilly.

apparently $1.99 for a box of toad on sale was still a bit much for a detergent that left your clothes fresh as a swamp lilly.


:)

I would think that the voltage induced by a collapsing magnetic field can get
a little high, I'm sure you observed voltage ratings on replacement parts,
and heat tolerances, still, a new part can turn out to be bad....

Good to see you are taking an analytical approach to this... I look forward to
you locating the part causing this and posting it.... Possibly with a schematic
shot of the section.... Good reference for the future....

Again, good luck !

.

Justin,

I agree with Old Coot88, if the TV had been working normally after the rebuild before this problem developed, then it most probably is the Horizontal Output tube.

There is a lesser chance that it is the Horiz Osc / Horiz AFC tube.

Another test would be to observe in dim light and see if the Horizontal Output tube's plates are slightly glowing when the tube warms up. If so, it is either a failing tube, or something in the circuit is throwing the voltages off.
In these early sets a misadjusted horizontal setup or failing component can cause the horizontal output tube to pull too much current.

In this case, if replacing the tube does not cure glowing plates, I'd go after the problem with a VOM rather than the 'scope that you mentioned.

If the problem started with the rebuild, in addition to the above, also include the C8 (Sams) cap or C91 (Factory) cap in series with the horizontal side of the yoke. C8 in Sams is shown as either a .5MFD 100V paper(?) or a .5 ohm at 15,750 electrolytic, while C91 in factory is only listed as a .5 ohm @ 15,750 cycles 100 volt electrolytic. This Cap can change the loading on the flyback and possibly cause ringing.

That big boy should be an electrolytic. A paper cap might work OK, but a ceramic probably will not.

And speaking of "cap" or "trap", who is the character that replaced Admiral Ackbar in your avatar?

James

Assuming that it's not a tube, why not try a can of freeze it spray, alternating with a hair dryer? I've found lots of faults that way over the years. Assuming yours is a heat related fault, of course.

Yah, that is a thought.... You would probably have to use the hair dryer to help heat
up the set, then cool down suspected parts.... Removing the chassis will keep it a little
cooler I would think..... I looked at the schematic last night, there are not many caps to
suspect..... If it turns out to be a cap, I hope you have one of those old "eye" type
cap checkers so you can show us what type of fault it turns out to be.... Good Luck...

.

In standard flyback circuit operation, the left hand deflection is through the damper tube. The right hand scan is through the horizontal output tube. There appears to be a high frequency oscillation occurring when the horizontal output tube conducts.

What does the waveform on the control grid of the horizontal output tube look like?

I agree with Old Coot88, if the TV had been working normally after the rebuild before this problem developed, then it most probably is the Horizontal Output tube.

There is a lesser chance that it is the Horiz Osc / Horiz AFC tube.

Another test would be to observe in dim light and see if the Horizontal Output tube's plates are slightly glowing when the tube warms up. If so, it is either a failing tube, or something in the circuit is throwing the voltages off.
In these early sets a misadjusted horizontal setup or failing component can cause the horizontal output tube to pull too much current.

In this case, if replacing the tube does not cure glowing plates, I'd go after the problem with a VOM rather than the 'scope that you mentioned.

If the problem started with the rebuild, in addition to the above, also include the C8 (Sams) cap or C91 (Factory) cap in series with the horizontal side of the yoke. C8 in Sams is shown as either a .5MFD 100V paper(?) or a .5 ohm at 15,750 electrolytic, while C91 in factory is only listed as a .5 ohm @ 15,750 cycles 100 volt electrolytic. This Cap can change the loading on the flyback and possibly cause ringing.

That big boy should be an electrolytic. A paper cap might work OK, but a ceramic probably will not.


The set did nothing aside from heat the ambient air with its electrolytics when brought up on the variac, so I have no idea if this problem existed prior or was something I built in. The plates of the HO tube look perfectly normal; no blue glow or abnormal heating.


And speaking of "cap" or "trap", who is the character that replaced Admiral Ackbar in your avatar?

That is "Pilot" from Farscape on the CTC-7. I miss Ackbar but it was time to change thing up a bit. :)

Assuming that it's not a tube, why not try a can of freeze it spray, alternating with a hair dryer? I've found lots of faults that way over the years. Assuming yours is a heat related fault, of course.

YES. I'm going to try this. A great suggestion.

In standard flyback circuit operation, the left hand deflection is through the damper tube. The right hand scan is through the horizontal output tube. There appears to be a high frequency oscillation occurring when the horizontal output tube conducts.

What does the waveform on the control grid of the horizontal output tube look like?

Ah okay, I did think that it was the opposite of this. If this is the case, there are plenty of more components to suspect.

First I'm going to try the old freeze spray trick, then get some VOM readings and as a last resort haul in the scope.

Originally Posted by Penthode View Post
In standard flyback circuit operation, the left hand deflection is through the damper tube. The right hand scan is through the horizontal output tube. There appears to be a high frequency oscillation occurring when the horizontal output tube conducts.

What does the waveform on the control grid of the horizontal output tube look like?


Ah okay, I did think that it was the opposite of this. If this is the case, there are plenty of more components to suspect.


Because the ripples are on the right and because the ripples occur while the horizontal output tube is conducting, the HO tube may be modulating the sweep with the ripple on the control grid. If the ripple is being conducted through the grid, I would be very suspicious of the decoupling capacitor (electrolytic) feeding the horizontal oscillator.