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  #61  
Old 09-30-2013, 04:26 PM
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Quote:
Originally Posted by zeno View Post
Yes C-1 is Zeniths term for composite video. Some sets
even have a "C-1 adjust" pot.
Grounding the ABL base proves its NOT coming from there so ignore
all between the ABL base & tripler.

Depending on the scope I was using I almost never used
DC only AC since I was looking at waveforms. On my sencore
there was a built in meter to speed things up.
Also be sure all your calibrations are set. The are the red
knobs are set to "cal". Some have an arrow to show which direction
to turn them.
If the scope is dual trace you can use sync on B to stablize the
waveform. Hook the B channel probe to a clean hoz signal
such as the hoz drive collector, this may get rid of the multiple
traces.

73 Zeno
I'm using the horizontal trigger of the pattern generator. Is that basically the same as using the B channel on a clean horizontal signal?

Yes, the red knobs are in the calibrated position. Not ready to mess with those kinds of adjustments.

When I check the C1, I get a staircase type pattern. Is that what it's supposed to look like? I have the pattern generator on the color bars w/IQW and chroma off. That gives me long b&w bars on the screen.

Inside the set there's a sheet glued to the wall. It has a section w/the heading of "Major Test Points". The first one is C1 (Picture Detector Output). The other two are used for calibrating the ACC and some IFAGC.
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  #62  
Old 09-30-2013, 04:34 PM
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Quote:
Originally Posted by jr_tech View Post
Without knowing the specs. for the 125V supply, it would *seem* to me that 3.5 volts of garbage would be more than I would like to see. Perhaps there are some filter caps in the 125V supply that are not functioning properly.
jr
Thing is, I can only find two capacitors and a coil on one feed of the 125V line. The caps were originally in the canister, but I replaced them when I recapped the set. That's on one end of the 125V. The other end has no caps that I can find and it is from a separate transformer. Not sure why there are two 125V feeds and from different transformers. The two leads join up at the horizontal board to complete the loop.
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  #63  
Old 09-30-2013, 04:52 PM
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Quote:
Originally Posted by TinCanAlley View Post
Now I tried scoping the other 240V boost.
I don't understand "other"... are you saying that the set actually has *two* sources of 240 Volt "boost voltage"... I suspect that there is only one source and it is distributed to other boards that may be marked "B+ or 240V", but these are boards where the 240V is used, not produced?
jr

Add: same for the 125V supply... two sources would seem to be unlikely.

Last edited by jr_tech; 09-30-2013 at 04:55 PM. Reason: add 125 v comment
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  #64  
Old 09-30-2013, 04:54 PM
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How would I test the filter choke on the 125V line? My understand is it removes the AC ripples and lets the DC pass. It's specs are: Current .48ADC, DC resistance 16ohm, Inductance 75mh.

One lead of this is connected to one of the caps that used to be in the canister and the other end connects to a post where there are a bunch of boost and other diodes and also a white wire that goes up to the other capacitor that used to be in the canister.
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File Type: jpg Under Chassis Filter Choke Small.jpg (98.1 KB, 8 views)
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  #65  
Old 09-30-2013, 04:56 PM
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Quote:
Originally Posted by jr_tech View Post
I don't understand "other"... are you saying that the set actually has *two* sources of 240 Volt "boost voltage"... I suspect that there is only one source and it is distributed to other boards that may be marked "B+ or 240V", but these are boards where the 240V is used, not produced?
jr
Yes, it comes from the same point. The SM lists them as boost(A) and Boost(B). Boost(B) gets extra treatment by way of a coil (peaking 550uh). Not sure what that does.
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  #66  
Old 09-30-2013, 05:14 PM
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So "boost B" has more filtering and therefore less noise than "boost A"?

jr

Last edited by jr_tech; 09-30-2013 at 05:31 PM.
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  #67  
Old 09-30-2013, 05:27 PM
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Quote:
Originally Posted by jr_tech View Post
So *boost B" has more filtering and therefore less noise than "boost A"?

r
I don't know. I haven't gotten back to trying to get a trace. When I first tried, the settings used for boost(A) didn't work. I started upping the scan rate for the trigger and started to get something recognizable. I'll give it another shot tonight.

I figured the peaking coil might have done something that I need to compensate for.
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  #68  
Old 09-30-2013, 06:17 PM
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Tin Can;

Your jail bars are generated in the flyback area or Horiz Yoke area, not the low voltage power supply. Not even the caps in the low voltage power supply. The low voltage PS is designed to filter out 60hz, not so much the 15K spike traveling throughout your tv. And you will see it everywhere, but its made in one spot, and its pretty strong to get everywhere....Is the size of the horiz pulse off the driver transistor the right size and shape? This drives the horiz. output transistor.

Lets see, The biggest problem to solving or making progress in this, is that all of us don't have a schematic. So, at least you should post the horiz, section, From the Horiz Osc, to the high voltage wire to the picture tube.

Also, there are things called decoupling capacitors. They take the signal generated by a noisy item and run it to ground. They are not called that on any schematic for your tv, but they are there..... They are near the horiz output circuit, it will be a 30uf cap, or less and it runs the sharp point of the horiz pulse driving the horiz output transformer to ground.

If you remember I posted a picture with lots of red dots, find similar items near the horiz. output transformer on your schematic, and begin replacing them. Check for an open coil near it, or open winding leg on the flyback that goes to a cap to ground. You should check each winding on the flyback for posted resistance to see if one is open, or changed value.
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  #69  
Old 09-30-2013, 07:40 PM
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Quote:
Originally Posted by Username1 View Post
Tin Can;

Your jail bars are generated in the flyback area or Horiz Yoke area, not the low voltage power supply. Not even the caps in the low voltage power supply. The low voltage PS is designed to filter out 60hz, not so much the 15K spike traveling throughout your tv. And you will see it everywhere, but its made in one spot, and its pretty strong to get everywhere....Is the size of the horiz pulse off the driver transistor the right size and shape? This drives the horiz. output transistor.

Lets see, The biggest problem to solving or making progress in this, is that all of us don't have a schematic. So, at least you should post the horiz, section, From the Horiz Osc, to the high voltage wire to the picture tube.

Also, there are things called decoupling capacitors. They take the signal generated by a noisy item and run it to ground. They are not called that on any schematic for your tv, but they are there..... They are near the horiz output circuit, it will be a 30uf cap, or less and it runs the sharp point of the horiz pulse driving the horiz output transformer to ground.

If you remember I posted a picture with lots of red dots, find similar items near the horiz. output transformer on your schematic, and begin replacing them. Check for an open coil near it, or open winding leg on the flyback that goes to a cap to ground. You should check each winding on the flyback for posted resistance to see if one is open, or changed value.
Okay, the file was too large to upload, so I've copied portions of it into a word file and then created a new PDF. I'll attach it to this reply and hope it will work.

When I checked the horizontal pulse it was correct. I will double check it just to be 100% certain it is as should be (shape and voltage).

I'll try to locate that posting with the red dots.

So if I remove power, what else do I need to do to safely measure each winding of the flyback?

The 30uf cap you mention, is that would be an electrolytic? If so, I replaced all of them already. The only other I can find are the disc kind.
Attached Files
File Type: pdf 25EC58 Schematics.pdf (690.1 KB, 11 views)
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  #70  
Old 09-30-2013, 08:01 PM
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Quote:
Originally Posted by Username1 View Post
Tin Can;

....Is the size of the horiz pulse off the driver transistor the right size and shape? This drives the horiz. output transistor.
I did the H Pulse and Sweep again. While they both look like they should, the sweep is supposed to be 120V according to Sams. But with a 50 V/Div, it takes up roughly 3.5 divisions. That would make it 175V. The pulse was on 20 V/Div and it takes up 3 divisions. That makes it 60V and Sams has it as 50V.
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File Type: jpg Horizontal Sweep Small.jpg (44.9 KB, 6 views)
File Type: jpg Horizontal Pulse Small.jpg (32.2 KB, 5 views)
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  #71  
Old 09-30-2013, 08:15 PM
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Quote:
Originally Posted by Username1 View Post
Tin Can;

Also, there are things called decoupling capacitors. They take the signal generated by a noisy item and run it to ground. They are not called that on any schematic for your tv, but they are there..... They are near the horiz output circuit, it will be a 30uf cap, or less and it runs the sharp point of the horiz pulse driving the horiz output transformer to ground.
I found the cap running off the horizontal output transformer. It's a 47uf and was replaced.
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  #72  
Old 09-30-2013, 09:06 PM
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I'm glad I started looking at the caps in the horizontal area. Seems when I recapped I put the 10uf 50V cap in backwards. It was my fault as I didn't have a radial and didn't want to order just for one cap. I went through my supply and found some of the audio grade Nichicon. I thought I was installing a KW series which has gold band for negative, but I put in an FW which has black for negative so the gold casing threw me off and I installed the negative based on the gold side. Odd it didn't explode, though.

Anyway, the cap has been replaced and the backwards one not reads as 5uf instead of 10uf. Don't know what it was doing to the set (if anything), but it sure didn't have anything to do with the jail bars as they're still there.

I also thought I put in the 47uf on the horizontal output transformer as it had + on ground, but looking over the schematics and pictures I took before the recap, it is supposed to be that way. Looking over all other caps while I was under there shows those are all installed correctly.
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Last edited by TinCanAlley; 09-30-2013 at 10:11 PM.
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  #73  
Old 09-30-2013, 09:12 PM
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I don't see the HV supply on the schematic... which page is it on?

jr
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  #74  
Old 09-30-2013, 09:19 PM
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Originally Posted by jr_tech View Post
I don't see the HV supply on the schematic... which page is it on?

jr
Do you mean the flyback (T207)? If so, it's on the second page bottom center. If that's not it, I'm not sure as I thought it was the HV supply.
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  #75  
Old 09-30-2013, 09:40 PM
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Thanks! I found it.
jr
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