View Full Version : GE 14T009 Restoration


Mre12ax7
07-16-2016, 04:11 PM
Hello,
I have been working on this GE for the past few weeks but am having a few issues.
So far I have replaced all the old paper and electrolytic capacitors, selenium rectifier , video detector diode and the AFC diodes.
Which has got me to this.
191806
As you can see it has horizontal and vertical lock but the horizontal jitters and does not lock in the right place. Sometimes though I can get it to lock correctly (not in picture) but it then goes to this.
191805
The picture is now very dim and shrunken in and no controls will bring it back to before, it must be turned off and then turned back on again to make it go back to normal.
This also happens when you mess with the horizontal hold control too much.
My longtime friend at the last radio/tv shop in town has suggested that the flyback is bad.
Does this seem correct? Or should I try different diodes for the AFC (I used 1N4007's).
I really would like to see this work as it is my first TV (I have done many radios).

Electronic M
07-16-2016, 06:26 PM
The flyback has to be at least usable for the screen to light.

Change out of tolerance resistors in the horizontal (AFC/osc/output) section, and see what that does. If yours has SS AFC diodes and not tubes then it is the later version of the chassis, and the hold control should be a potentiometer. There is also an adjustable horizontal oscillator coil/transformer that should be adjusted with a PLASTIC (never use a metal hex key, you will crack the core if you do) alignment tool...Try adjusting that osc. coil for a good synced picture, and then centering the hold control and readjusting the coil.

Mre12ax7
07-16-2016, 10:03 PM
I have replaced two resistors across the AFC diodes but not the one at the flyback.
It does not have a hold potentiometer.
It uses a hold coil with a plastic shaft that sticks out the back.
The flyback has a spot on the bottom that looks like it almost wants to drip and the wax is bubbled up around that area. Maybe it has a intermittent short?

DaveWM
07-17-2016, 11:20 AM
weak picture poor lock, AGC issue.
as far as the shrink in picture
Have you checked the B+ at turn on and then again as it shrinks. Monitor the B+ and the AC current draw, something like a gassy tube may be drawing more power as it warms up.
How is the HV holding up?
Have you tried new horz out/damper/HV rectifier (SOP if HV or sweep is an issue, must sub don't use a tube tester).

I assume the shrink is there when just a raster as well?
If you are going to do TV work a few must have items
HV prob
neon light for checking fly
Nice thing to have and can be gotten cheap
B&K 1076 analyst good for trouble shooting HV and for signal injection to trouble shoot RF/IF/video issues
Scope for checking wave forms and looking for things like hash on AGC and sync separation issues.
AGC variable DC supply for trouble shooting AGC issues (included on the Bk 1076).

Mre12ax7
07-21-2016, 04:07 PM
I got some 1N4148 diodes and put them in place of the 1N4007s. No change in the sync issue. Although the shrinking picture and dimness has gone away. I am starting to think that a resistor inside the high voltage cage is drifted and is causing this.

Eric H
07-21-2016, 05:44 PM
In the second picture it's clear the horizontal frequency has gone way off and you have multiple images side by side, something may be shorting causing it to do this.

Have you tried turning the horizontal control when this happens? Sometimes you have to keep turning until it flops over and over until it gets to the right frequency where you have only one image.

If it starts out okay then goes to multiple images then something's drifting or shorting pulling the oscillator off frequency. some cold spray on the components around the oscillator tube might show it up.

Mre12ax7
07-21-2016, 06:09 PM
Installing the 1N4148s fixed that problem.
It now just has the issue of showing 2 half pictures.
I have noticed some ghosting or noise in the picture the last time I powered it up.
The HV rectifier tube tests bad can it cause this?

Mre12ax7
07-22-2016, 10:39 PM
I have made a video showing all the problems
https://youtu.be/pSxqS_Wfp3s
As I adjust the horizontal hold you can see that the picture goes almost dark and cannot be brought back without turning off the TV.
I know about the vertical.

Mre12ax7
08-05-2016, 01:42 PM
I am stumped with this thing.
I have replaced a 100k resistor that I thought was the problem but it is not it.
Could this be a bad horizontal hold control?
FIY: This is my first TV. I've done plenty of radios but not a TV before.

zeno
08-05-2016, 01:59 PM
First thing try a NOS brand name hoz osc tube.
You seemed to have fixed the way off freq problem, now
you have a hoz AFC problem. Check from the diodes
through the osc. Be SURE caps are right value. Usually there
is at least one resistor feeding back from the FBT to the AFC.
Check that stuff also.

73 Zeno:smoke:

Mre12ax7
08-05-2016, 02:37 PM
I will get a new horizontal output tube later today.
The one is there is most likely the original as it is a GE branded tube.
I have replaced all resistors in the AFC circuit

Electronic M
08-05-2016, 03:01 PM
BTW I have a beat up version of this set with a restored working chassis and a weak CRT that I've been trying to sell. You could make one real nice one out of two....PM me if interested.

Eric H
08-05-2016, 05:40 PM
Be sure you hooked the AFC diodes up correctly, most are tied together at the cathode (banded end), but not all of them are.

If the vertical is rolling also you may need to go back a stage and check the circuit around the Sync Separator tube

Mre12ax7
08-05-2016, 06:29 PM
The diodes are in correctly.
Installing a new 12BQ6 made no difference in the lock but I have been unable to get it to go back to the weird thing with the dim and shrunken picture.
I have also noticed when I turn the contrast all the way down the image is more shaky.
The black bar on the screen is about 2 1/2" but if you turn down the contrast there is actually two bars, the larger bar and a smaller one inside it.
Do the lead length of the diodes matter?

Eric H
08-05-2016, 07:54 PM
I am guessing that since the sync signals are carried in the video signal that turning the contrast down is probably reducing the gain and the sync along with it which would make it more unstable at low contrast levels.

I still think it might be a problem with the sync separator circuit, it usually picks off the sync signal from the 2nd i.f. then sends it on to the vertical and horizontal. Anything disrupting the signal from the i.f to the separator could cause these issues, or something at the tube itself could be off.

If both the vertical and the horizontal won't sync then it's likely to be a problem at or before the separator tube, if only the horizontal won't sync it could be something between the separator and the Horiz oscillator or something wrong with the horizontal half of the separator tube. I don't have a schematic so I'm assuming certain things here.

maxhifi
08-05-2016, 08:35 PM
Note Zeno said horizontal osc. Tube not output.

Mre12ax7
08-05-2016, 09:02 PM
Since this is a lower end set the horizontal output tube is also the oscillator.
The vertical will sync fine.
All resistors connected to the AFC diodes have been replaced.
The 6AU8A sync separator tests fine on both sections with the sync section testing at 100%.

dieseljeep
08-05-2016, 10:37 PM
Since this is a lower end set the horizontal output tube is also the oscillator.
The vertical will sync fine.
All resistors connected to the AFC diodes have been replaced.
The 6AU8A sync separator tests fine on both sections with the sync section testing at 100%.

Sorry! Your statement regarding the horizontal output tube, being the oscillator is incorrect. The set uses a 6CG7 and a 12BQ6, horizontal output.
That model has always been tricky to trouble shoot in that circuit. There was two different variations in that circuit. One used the diodes and a 3AU6 audio IF tube and the earlier run used a 5AN8, for the audio and the triode side used as the horizontal AFC. I don't remember getting one of those sets working really perfect.

Electronic M
08-06-2016, 12:12 AM
Sorry! Your statement regarding the horizontal output tube, being the oscillator is incorrect. The set uses a 6CG7 and a 12BQ6, horizontal output.
That model has always been tricky to trouble shoot in that circuit. There was two different variations in that circuit. One used the diodes and a 3AU6 audio IF tube and the earlier run used a 5AN8, for the audio and the triode side used as the horizontal AFC. I don't remember getting one of those sets working really perfect.

Agreed on the out put and osc being different tubes. There were 2-3 versions of this chassis. Not only were there ones with tube vs diode horiz AFC, the osc tube was different among them. One verion (IIRC the later one) used a 7AU7 as the H osc.

Mre12ax7
08-06-2016, 07:40 AM
Yes I made a mistake about the tubes.
it uses the 7au7.
Which tested bad when I got the set and in there now is a new one.
I don't have any in my stash.
I do have 12au7s though and if I change the output tube to a 6 volt one it might work.
EDIT
Scratch that the filament current is different.

Mre12ax7
08-06-2016, 08:12 AM
I just tested the 7au7.
One side is weak the other is bad.
Something is killing this tube.

dieseljeep
08-06-2016, 10:39 AM
Agreed on the out put and osc being different tubes. There were 2-3 versions of this chassis. Not only were there ones with tube vs diode horiz AFC, the osc tube was different among them. One verion (IIRC the later one) used a 7AU7 as the H osc.

I have to agree to that statement. I completely forgot about the 7AU7, one of GE's favorites. IIRC, all versions of the 14T009's used the 7AU7. I'll check Riders.
BTW, to the OP, the 12AU7 tube has a different heater current, 150ma @ 12 volts and 300ma @ 6.3 volts. You're stuck with the 7AU7.
You can't change the horizontal output tube to compensate for a heater voltage difference. :sigh:

dieseljeep
08-06-2016, 10:42 AM
I just tested the 7au7.
One side is weak the other is bad.
Something is killing this tube.

Is the tube the original one? It's rather hard to kill that tube, unless the heater is over voltaged. :scratch2:

Mre12ax7
08-06-2016, 11:25 AM
No.
The original was bad so I replaced it but the one that I put in is bad too.
I will have to get a few and see which one it likes

Electronic M
08-06-2016, 01:24 PM
Test the tubes before putting them in. If you did not, it is possible the second 7AU7 was bad before it even went in the set. I've found NOS duds (and weak used tubes the same brand as on the carton) before.

Also occasionally a tube will have a defect that can damage the set....Like say a short between the plate of an IF tube to the grounded end of the heater....Which could fry the IF trans...There are many defects any given tube could have that could be harmful testing first saves you grief, and diagnostic effort at the cost of a little time.

Mre12ax7
08-06-2016, 03:29 PM
Test the tubes before putting them in. If you did not, it is possible the second 7AU7 was bad before it even went in the set. I've found NOS duds (and weak used tubes the same brand as on the carton) before.

That's what my buddy at the local tv/radio shop says.
I will have to go over there next week and pick up another 7AU7.

Mre12ax7
08-08-2016, 06:06 PM
The TV is now fixed.
The 7AU7A was the culprit.
Now to watch Twilight Zone...

zeno
08-08-2016, 09:12 PM
Rule was always try tubes first for the symptom before
you plugged in an iron or pulled the Sams. Then if no joy
repair it with a new tube in place. Sub back the old one
& give it a days test run.
One thing is garbage new tubes. Ones I remember were IEC
& Lindal. Many others to. The HOT's were guarantied to give
snivets. We got some in a by out & only used them in last
leg sets & sold at 1/2 price. Still made $$, only paid a dime
each. Only use brand name tubes that bear the name of a
major maker & u r good 99% of the time.
Glad you got her going, now time to get another on the bench !

73 Zeno:smoke:

dieseljeep
08-09-2016, 10:30 AM
Rule was always try tubes first for the symptom before
you plugged in an iron or pulled the Sams. Then if no joy
repair it with a new tube in place. Sub back the old one
& give it a days test run.
One thing is garbage new tubes. Ones I remember were IEC
& Lindal. Many others to. The HOT's were guarantied to give
snivets. We got some in a by out & only used them in last
leg sets & sold at 1/2 price. Still made $$, only paid a dime
each. Only use brand name tubes that bear the name of a
major maker & u r good 99% of the time.
Glad you got her going, now time to get another on the bench !

73 Zeno:smoke:

You brought back some memories about some of the tubes a buddy and I bought almost 60 years ago.
I think, there was around three firms that sold 33 cent tubes, advertised in Popular Electronics. Thirty tubes for ten bucks, what a bargain! :D
Then there was NJRT tube co. IIRC, they were Tung-Sol rejects. Olson had Akrad and Schield, they looked like Sylvanias. :scratch2:

Mre12ax7
08-10-2016, 08:20 AM
Is there any kind of width control on these?
Its kind of stretched out to the right.
Or do I keep playing with those darn centering rings.

dieseljeep
08-10-2016, 11:24 AM
Is there any kind of width control on these?
Its kind of stretched out to the right.
Or do I keep playing with those darn centering rings.
Is the picture non-linear, being stretched out on the right, or is there a margin on either side? Non-linearity would be a fault in the damper circuit.
Were the caps in the damper, boost circuit replaced with the correct values? Also sub the damper and horizontal output tube.
I looked in the GE coverage in Riders and it shows no width and linearity adjustments.

maxhifi
08-10-2016, 06:56 PM
Is the picture non-linear, being stretched out on the right, or is there a margin on either side? Non-linearity would be a fault in the damper circuit.
Were the caps in the damper, boost circuit replaced with the correct values? Also sub the damper and horizontal output tube.
I looked in the GE coverage in Riders and it shows no width and linearity adjustments.

Old TV shows seldom had any valuable information at the extreme left and right edges of the screen, so overscan was acceptable and even useful, to conceal the effects of line voltage variations for example. With modern program material a lack of adjustments to me is a big strike against a vintage set.

Some TVs have a width coil in the flyback circuit which can be adjusted. I've tried to figure out how to retrofit one into a TV which lacks this feature but never got it.