Sylvania Superset Update

[TrllVl90]

I replaced (what I assume is) the boost cap as the old one blew out its bottom and was so far gone one of the leads was broken off on the inside of the cap, I reflowed all the joints on sand around the flyback, I cleaned the inside of the housing. I included a couple before and after photos.

The speaker buzz is still occurring in a slow pulse (approximately 10 seconds of no buzz, 20 seconds of buzz), there were no other visibly bad caps on the board, so I may just replace a bunch in that area of the circuitry.

And while I was cleaning the inside I knocked the convergence & purity rings out of position with my dumb limbs. I ordered an hdmi to RCA converter so I can try to fix my screw up there running test screens off my laptop.

Last thing, I didn't touch the pots on the main board for picture/brightness/color etc, but on the front pots I'm running it with picture & color roughly 2/3 up, and the brightness pot almost all the way off. (I can turn brightness & picture all the way down and still seem an inage, although probably not in a really bright room).

Anyway I just wanted to post this and say thanks again for your help. Overall I'm pleased as punch.

-Sean

[old_tv_nut]

First off, if this is an update of another thread, it should be posted there.

Regarding the picture with the red smearing to the right of the forehead, and brightness all the way off, that's a clear indication that the CRT bias (screen controls) are set wrong and the red video output is going into saturation on highlights. Going through the setup procedure should fix it.

[TrllVl90]

Sorry I'll try to get this thread deleted and this response in the proper place once I figure out how.

As for the red smearing it's way better now that I've replaced the busted capacitor, but it's there if I crank the color pot all the way up, I'll have to find a setup how-to and follow along.

In the mean time, any thoughts on a slow pulsing buzz coming from the speaker?

[old_tv_nut]

In the absence of setup instructions, you can take a stab at it.

If this set has a SETUP switch, switch to setup mode, which should give a single horizontal white or gray line. Turn down the G2 (screen) R,G,B controls until you just barely see a neutral dark gray line. Switch out of setup mode and adjust the brightness control as needed.

If there is no setup switch, try turning down the brightness some with the G2 (screen) R,G,B controls and then turning brightness back to normal with the brightness control. You may end up with a color tint in the shadows; fix that by turning down the predominant one or two of R,G,and/or B.

Note: some sets had a jumper to set the G2 range to higher or lower.

[old_tv_nut]

About the buzz - sorry, no idea.

[TrllVl90]

Thanks i'll give that a try. And sorry I can't figure out how to delete this thread.

[JohnCT]

Originally Posted by TrllVl90

As for the red smearing it's way better now that I've replaced the busted capacitor, but it's there if I crank the color pot all the way up, I'll have to find a setup how-to and follow along.

Even with bad setup, a strong tube won't flare like that except for the auto-AKB twin focus models like Zenith made when the G2 was set too low.

Remember that the CRT heater voltage is sourced from the fly, so if your HV is low, your filament voltage will be low in a proportional amount. Even an otherwise strong tube will flare with low filament voltage.

With a TRMS meter, measure the filament voltage (AC) at the CRT socket to see if you're getting 6.3V. Don't use an analog meter and don't use a meter that isn't a true RMS type because your AC is at the horizontal rate, not 60hz.

If the voltage is low, your HV is also low, and that could have to do with the retrace capacitor you changed (as well as other things such as B+)

John

[zeno]

The jug sure looks soft especially the red. If the G-2 & heater check out we can give you a cheat. I dont think its a Zenith EFL, IIRC NAP never used it.
Between NAP, RCA / Thompson & Zenith they built almost all US tubes
and many for JA & Korean sets. May be one reason neither had EFL's.

73 Zeno
LFOD !

[TrllVl90]

Originally Posted by JohnCT

Even with bad setup, a strong tube won't flare like that except for the auto-AKB twin focus models like Zenith made when the G2 was set too low.

Remember that the CRT heater voltage is sourced from the fly, so if your HV is low, your filament voltage will be low in a proportional amount. Even an otherwise strong tube will flare with low filament voltage.

With a TRMS meter, measure the filament voltage (AC) at the CRT socket to see if you're getting 6.3V. Don't use an analog meter and don't use a meter that isn't a true RMS type because your AC is at the horizontal rate, not 60hz.

If the voltage is low, your HV is also low, and that could have to do with the retrace capacitor you changed (as well as other things such as B+)

John

Hey,

Okay, the SAMS lists the filament voltage at 22V. I'll check. Also I'm not quite sure what you mean by "B+".

As for the softness of the image, I did knock the convergence rings out of place with my arms while I was cleaning dust out of the cabinet (accidentally, of course). I haven't tried realigning them yet. The picture was much sharper before then, smearing aside.

Edit: I just checked the multimeter I have at home, and it's not TRMS, so I'm going to have to wait until I get back to work, and see if the ones we have there are.

Edit2: In regards to the misaligned convergence rings, I did position them back close to how they were, but obviously I didn't do the best job.

[Electronic M]

B+ is basically a universal electronics term for the power supply voltage(s).

It dates back to the tube battery radio era. Back then the heaters would be powered by an A battery, the plates would be powered by a B battery and the grids would be biased by a C battery. Eventually they figured out how to make the B battery bias the grids with resistors, then they figured out how to make AC power supplies do the work of batteries (causing battery radio bonfires in many cities in the late 20s), but the A and B designations stuck...A fell out of use with the transistor and certain solid state devices started using VCC, VDD, VBB and or supply design voltage as designations, but B+, and B- are still in common use, and far from dead.

Your useless trivia lesson for the day...

[TrllVl90]

Originally Posted by Electronic M

B+ is basically a universal electronics term for the power supply voltage(s).

It dates back to the tube battery radio era. Back then the heaters would be powered by an A battery, the plates would be powered by a B battery and the grids would be biased by a C battery. Eventually they figured out how to make the B battery bias the grids with resistors, then they figured out how to make AC power supplies do the work of batteries (causing battery radio bonfires in many cities in the late 20s), but the A and B designations stuck...A fell out of use with the transistor and certain solid state devices started using VCC, VDD, VBB and or supply design voltage as designations, but B+, and B- are still in common use, and far from dead.

Your useless trivia lesson for the day...

Not completely useless, definitely interesting.

[zeno]

Tom gives a good run down on B+. One of the terms you will CONSTANTLY see
used here. If you look at any little radio the battery is the B+ source.
On your set odds are the heater is NOT the problem. If the G-2 is
set right look at this:

The pix is bad when the set is cold but gets better with time.
The pix improves with reduced brightness & contrast.
Thats all assuming the 200 V DC for the three video outputs is good.
At this point a manual would be needed. Any NAP chassis will work if
a close match ( C-5, C-6 etc. ).

73 Zeno
LFOD !

[TrllVl90]

Originally Posted by zeno

Tom gives a good run down on B+. One of the terms you will CONSTANTLY see
used here. If you look at any little radio the battery is the B+ source.
On your set odds are the heater is NOT the problem. If the G-2 is
set right look at this:

The pix is bad when the set is cold but gets better with time.
The pix improves with reduced brightness & contrast.
Thats all assuming the 200 V DC for the three video outputs is good.
At this point a manual would be needed. Any NAP chassis will work if
a close match ( C-5, C-6 etc. ).

73 Zeno
LFOD !

Both things you suggeted is right. The picture is worse at the beginning, but gets better over time; and the picture is a little clearer during dark scenes (and turning down brightness/contrast. I set it at 2/3 contrast, almost 0 brightess, since that gave me a decent picture, and the brightness isn't necessary to see anything.) Not to say that at any point the picture is terrible, just a bit blurry. ALSO I set the Color pot to like 2/3 as well. All the way up is way too much color to me.

I have the appropriate manual for this TV + Chassis, unfortunately it's over the file size limit, and even making a compressed file leaves it over the limit. I'll have to find an alternative way to share it.

If anyone else has a smaller file manual, it's a 26C8 Chassis.

Edit: I haven't checked the G2 yet, but this is what it's doing at its current settings.

[JohnCT]

Originally Posted by TrllVl90

Hey,

Okay, the SAMS lists the filament voltage at 22V.

As for the softness of the image, I did knock the convergence rings out of place with my arms while I was cleaning dust out of the cabinet (accidentally, of course). I haven't tried realigning them yet. The picture was much sharper before then, smearing aside.

It's not 22V, it's 6.3VAC on that tube. I literally worked on a thousand of them. Sams misprint I suppose.

The flaring in your picture is not a convergence issue. Misconvergence will show as a clearly defined border of color, not a general lazy flaring off the picture on brighter images.

Hopefully, your HV is low, which can happen if the retrace capacitor is too high in value compared to the original (it must be an *exact* value - no upping by 10-20% like other caps allow). If the HV is low, your filament will be low and will cause that general flare off the bright on-screen objects.

As tubes get older, they become more sensitive to filament voltage than when they'r new. Most CRT testers of the time had a "life" test. Pushing the "life test" button would reduce the filament voltage a few tenths up to a half of a volt. A strong tube would barely lose emission but a weak tube would drop into the "yellow" or "red" area.

Ordinarily, a flare like that is a soft tube, but since you changed the retrace cap which has a big effect on the HV (and therefore filament), checking the filament voltage at this stage is the best thing to do.

If the voltage is 6.3 (not 6.1!) with a TRMS meter, your tube is soft and your repair was fine. If the filament is low, revisit your retrace cap change and double check the value.

John

[TrllVl90]

Originally Posted by JohnCT

It's not 22V, it's 6.3VAC on that tube. I literally worked on a thousand of them. Sams misprint I suppose.

The flaring in your picture is not a convergence issue. Misconvergence will show as a clearly defined border of color, not a general lazy flaring off the picture on brighter images.

Hopefully, your HV is low, which can happen if the retrace capacitor is too high in value compared to the original (it must be an *exact* value - no upping by 10-20% like other caps allow). If the HV is low, your filament will be low and will cause that general flare off the bright on-screen objects.

As tubes get older, they become more sensitive to filament voltage than when they'r new. Most CRT testers of the time had a "life" test. Pushing the "life test" button would reduce the filament voltage a few tenths up to a half of a volt. A strong tube would barely lose emission but a weak tube would drop into the "yellow" or "red" area.

Ordinarily, a flare like that is a soft tube, but since you changed the retrace cap which has a big effect on the HV (and therefore filament), checking the filament voltage at this stage is the best thing to do.

If the voltage is 6.3 (not 6.1!) with a TRMS meter, your tube is soft and your repair was fine. If the filament is low, revisit your retrace cap change and double check the value.

John

Okay, i'll do that. Thank you for the explanation. Sometimes the terms used don't translate in my head properly.