View Full Version : Ghost Issue


VA561
12-20-2015, 12:20 PM
My '59 RCA ctc-9 has a ghost image that I can't seem to get rid of. Any input would be appreciated. I use the same dvd player and rf converter with my other tvs so I have ruled that out. The fine tuning adjustment does nothing to get rid of it. Don't know what else to try. the ghost image is only on the right side of the picture.

Tom S
12-20-2015, 12:35 PM
How long have you had the set and did you recap the power supply? I have seen weird things due to power supply caps.

old_coot88
12-20-2015, 12:57 PM
Try subbing the last IF tube.

VA561
12-20-2015, 01:28 PM
I have had the set about a month. Previous owner recapped the set. I replaced one of the tuner tubes, the 6EA8 because the picture was "grainy". The tube was bad (shorted),that took care of that problem. The 6BC8 was "gassy" but seemed to be ok otherwise. I think I will scrounge up another one of those to see if that helps to get rid of the ghost.

miniman82
12-20-2015, 02:25 PM
99% of the time it's either a wore our detector crystal or the IF alignment is funky. I can bring my jig over, but it's a pretty involved process.

kf4rca
12-20-2015, 04:04 PM
Does the ghost move sideways as you adjust the fine tuning?

walterbeers
12-20-2015, 04:20 PM
I had the exact same problem with a CTC 9 many years ago. Ghost is to the right of images and does no go away with anything. I did find the problem though. One that most techs never think of. It's caused by a bad delay line. Short across the input and output of the delay line and I bet it disappears although the color will be offset. I can almost bet the ghosting will be gone. Just find another delay line from another old retro RCA. Replace it and you will have a nice ghost free picture.

zeno
12-20-2015, 04:56 PM
I 2nd the delay line. Had a few on 60's sets IIRC RCA's.
Also is the 6EA8 in the IF ?. Usually its mixer / osc in
the tuner.
After the delay line do the IF tubes & sub the tuner to be sure.
Alignment a LAST resort & I wouldnt do it without 3 NOS
exact number IF tubes........

73 Zeno:smoke:

VA561
12-20-2015, 05:42 PM
"Does the ghost move sideways as you adjust the fine tuning"?

No, the ghost pretty much stays where it is throughout the tuning adjustment.

"Also is the 6EA8 in the IF ?. Usually its mixer / osc in
the tuner."

Yes the 6EA8 is in the I/F. It is the mixer osc.
__________________

Electronic M
12-20-2015, 05:57 PM
Yes the 6EA8 is in the I/F. It is the mixer osc.

The mixer osc. is NOT part of the IF, but rather the tuner stage which feeds the IF.

VA561
12-20-2015, 06:08 PM
Sorry about that. It is in the tuner stage.

old_coot88
12-20-2015, 07:06 PM
Alignment a LAST resort & I wouldnt do it without 3 NOS
exact number IF tubes........
73 Zeno:smoke:
Ditto that, bro. I've had the last IF tube cause ringing more times than I can count. It was always the last IF.
But it sure can't hurt to sub 'em all before even considering alignment.

VA561
12-20-2015, 08:18 PM
I'll test the three I/F tubes tomorrow. It's easy enough to check those first.

wa2ise
12-20-2015, 10:13 PM
I 2nd the delay line.

3rd in the delay line, but maybe a terminating resistor has changed value? If that happens, some of the signal will bounce back to the delay line input, and back again.

Username1
12-20-2015, 10:32 PM
It's ringing somewhere, detector, or filter circuit after it....

.

old_coot88
12-20-2015, 10:57 PM
Last IF tube. At least eliminate it as a possibility. It can test 'Good' on a tester and still cause ringing. Subbing is the only way to tell. Seen this issue over and over back in the day. Always the last IF. Across multiple brands of color sets.

Penthode
12-23-2015, 11:55 PM
But I thought the last IF was eliminated by the fact the ghost did not change with changes to the fine tuning?

VA561
12-23-2015, 11:56 PM
I tried two tested, 3rd stage IF tubes. No luck.

old_coot88
12-24-2015, 12:55 AM
But I thought the last IF was eliminated by the fact the ghost did not change with changes to the fine tuning?
If the last IF is causing ringing/'ghosting', it does not change with the fine tuning.
Since VA561 has now subbed it a couple of times, that pretty well eliminates it.

Electronic M
12-24-2015, 02:53 AM
Have you considered having the RF/IF stages exorcised? :D

VA561
12-24-2015, 07:20 AM
yeah, I think thats the next step! The same person(s) who devised the most evil device ever made (the convergence board), has possesed the rest of the tv!

bluenorm
12-24-2015, 10:15 AM
hi miniman82 the detector cristal that you is the mentioned is cr302 pix detector on the if schematic board, or any other and if... any suggestions. the other detector in the if board is the sound one. are both the same?

miniman82
12-24-2015, 07:46 PM
I don't recall which is which, I haven't owned a CTC-9 for some years now. But I can tell you that the type of crystal does matter, if you don't want problems I suggest that you find a good testing original replacement or equivalent. Modern (silicon) diodes will have the wrong capacitance which throws off the last IF stage tuning, and they forward bias at different voltages. If memory serves the crystal one forward biased at around .223 volts, where nearly all modern silicon diodes will be at or above .5 vdc. I scavenge replacements from other sets or swap meets.

Username1
12-24-2015, 08:37 PM
It's the video ghost tube...... 3GH8A......

.

walterbeers
12-24-2015, 11:27 PM
With all of the posts, I still say it's caused by a bad delay line. Most likely it has a turn of wire inside the delay line that is shorted causing the ringing. You can do a real simple check. The delay line as you probably know is a long hollow cardboard tube soldered on the back side of the chassis, kind of towards the upper middle. It has 3 leads on it. One of them goes to ground. The other 2 is the video signal in and out. Back out the chassis far enough to keep it connected, and throw a clip lead across the input and output leads (wires) on the delay line. No need to disconnect them. The leads will be on opposite ends. Don't worry about disconnecting anything. Leave the ground wire alone. I can almost bet that the ghosting (ringing) problem will be gone, but you will notice the color will be displaced from the Y (black and white) signal. Attached is a picture of the underside of a CTC9. The long yellow tube (stick) is the delay line.

bluenorm
12-25-2015, 10:49 AM
thanks miniman82

oldtvman
12-25-2015, 12:22 PM
Make sure you don't a broken ground on the IF cable from the tuner, and check grounds on the IF board.

miniman82
12-25-2015, 04:05 PM
Not saying it can't be a delay line, I just find it hard to believe. I've had a lot of sets, never had an issue with that part. Incorrect termination can also cause issues, and the resistors are easy to check.

Bill R
12-26-2015, 10:55 AM
I don't recall many delay actual delay line problems period. The few I have encountered have been open lines that caused only chroma to be displayed. the ones that were shorted caused poor color fit. Not ghosting. Of course this is based on servicing them in the 70''s and now delay lines could be a problem. If it is in the delay line circuit I would suspect an impedience mismatch at one end. Check the terminating circuits. I have also seen this problem caused by poor IF response. I know the dreaded alignment. Could be a bad cap in the IF. Especially if they are hidden in the IF can. Bad soldering of the board to all the ground stakes can also cause it. I would reflow them and not depend on seeing a crack. Just do it. Same with all the boards. Alignment is really not that bad if you have access to the equipment. Even if you make no adjustments an alignment hookup could tell you a great deal about how well the IF is preforming. Also don't overlook any peaking coils in the video circuits.
good Luck.

miniman82
12-26-2015, 11:57 PM
I'm slated to pop on by tomorrow anyway, it's probably something simple.

Penthode
12-27-2015, 02:18 AM
If the last IF is causing ringing/'ghosting', it does not change with the fine tuning.
...

Alas, you are incorrect. If the last IF tube was indeed bad as suggested, the ringing would change with the fine tuning adjustment.

Since it had been suggested the last IF tube may be responsible, think for a moment the consequences in the change in the IF response which would result in the ringing or ghosting. A peak in the IF response would occur and when the fine tuning is changed, the video band would sweep the peak in the faulty IF response so that the frequency of the peak in the demodulated video band would change as a consequence. In other words, the ghost spacing would change as the fine tuning is adjusted.

If adjusting the fine tuning does not change the ringing spacing, then the problem must be after the second detector eg in the video amplifier. As has been pointed out, a badly terminated delay line would alter the baseband frequency response.

DaveWM
12-30-2015, 02:22 PM
Did you try a direct injection of a composite signal at the 1st video amp? that should clear everything (tuner/IF/detector diode) before it. divide and conquer.

miniman82
12-30-2015, 05:50 PM
Swung by last weekend, the ghosting is changing with adjustments to the fine tuning so I think this is going to be either an IF alignment or tuner link issue. We had to get better convergence before delving into that though, and found that the blue horizontal pot did nothing. It wound up being burned up and open in places, so Larry is looking for a new 120 ohm wirewound pot to replace it. Once that's fixed, we can solve the ghosting problem.

old_coot88
12-30-2015, 09:56 PM
Alas, you are incorrect. If the last IF tube was indeed bad as suggested, the ringing would change with the fine tuning adjustment.
You may be right, and probably are. It's been a lotta years ago, and I don't recall noting whether it correlated to fine tuning.
Just curious, how many cases of last IF ringing have you actually encountered? I've seen it in 3 stage strips as well as the oddball two stage (6EH7, EJ7) strips).

VA561
01-17-2016, 05:54 PM
:) I've decided to just live with it. It has a pretty good picture otherwise. I have to remind myself that this is a 56 year old tv. I'm just glad it functions when I turn the set on.

miniman82
01-17-2016, 07:27 PM
I do think it could be a little better, trouble is making it better means a complete convergence setup. I don't think it's worth all the effort, it's good enough now.

walterbeers
01-17-2016, 08:15 PM
I know delay lines seldom fail, but just for curiosity's sake try putting a clip lead across the 2 ends of the delay line. Don't clip anything to the ground side. and see if the ringing (or ghosting) disappears. I battled this exact problem for months before I found it. The "new" delay line solved the problem. I guess I'm really curious myself if that's your problem or not.

miniman82
01-17-2016, 11:28 PM
It's not the delay line, I've seen it in person.