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 Post subject: Re: GE 805 "Locomotive" Restoration Help
PostPosted: Jan Mon 16, 2023 5:05 pm 
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Ok. I'm printing out the riders edition today and I'm going to move forward using that. It gets confusing juggling between the two. Also. I did check a few other tubes and many readings were way off. This set is pretty complex (for me anyways). How is it the filament voltages are all pretty much different. Aren't most of these tubes rated for 6.3v? Also. I'm ok testing both strings using the same b- ground right?

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 Post subject: Re: GE 805 "Locomotive" Restoration Help
PostPosted: Jan Mon 16, 2023 5:28 pm 
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The first digit or first 2 digits of a tube type number tell you what the filament voltage for that tube should be. All the tubes in one series string of tubes will want the same current. So if the voltages for all the tubes in one string add up to close to 117 (the power line voltage) then each tube will get it's expected voltage. Note the one tube that needs a higher current than the rest of them. And note that the current from both strings of tubes pass through that tube.

If you enter a tube type number into Google you should be able to find a specification sheet for that tube.

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 Post subject: Re: GE 805 "Locomotive" Restoration Help
PostPosted: Jan Tue 17, 2023 12:01 am 
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The fact that you are seeing 0V on pin 12 of the CRT and about a bit more than 6V on pin 1 of the CRT would indicate that you have the version "S", "T", "U" or "W" of the chassis. The "early" version has a much higher voltage on the CRT filament pins because of the way B- is hooked up. There may be a mistake on the Riders voltage diagram, it indicates "S" and "T" have the same filament voltages as the "early" version.
According to the schematics that is not so.

The filaments in each string of filaments and the 75 ohm resistors should add up to approximately 117V.
A "6V" tube actually is spected as 6.3V, a "12V" tube is spected as 12.6V. You have to check the tube data on the other tubes to find exactly what the optimum voltage is.

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 Post subject: Re: GE 805 "Locomotive" Restoration Help
PostPosted: Jan Sun 22, 2023 3:41 am 
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Well I had a chance to spent a little time with the set tonight after replacing the Audio output (25L6GT). I also put in a NOS 19BG6G. After soldering that resistor a accidentally left J-hooked in the focus circuit. I was hoping for the best and at first it was very improved. I managed to get even screen size with straight lines top and bottom. The picture also looked improved. After 5 or 10 minutes of adjusting things I was once again left with this vertical distortion line that comes and goes. The longer the set is powered the worse it gets. Eventually its pretty much permanent and leaves the image pretty distorted. None of the controls effect it. It seems like all of the controls are working as they should. Unfortunately once this distortion starts I can't fine tune anything anymore. It does it regardless of what channel I'm on and also does it with no source hooked up. Some component is heating up and causing this. Resistor or Mica cap maybe? Could this be a tube issue? I honestly have no idea where to go from here.

Also,

I installed a CL-90 in series on one side of the filament resistors. Honestly, it makes little to zero difference on the power up time. The filaments light up right away. These thermistors are not polarized correct? I found that odd.

What do you guys think?

See video link.

https://youtube.com/shorts/e52Nw_fC-sQ?feature=share


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 Post subject: Re: GE 805 "Locomotive" Restoration Help
PostPosted: Jan Sun 22, 2023 4:15 pm 
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I've got to say I've never see anything exactly like that before.
To me it looks like the horizontal sweep is stopping during retrace and having to come up to speed at the start of a new vertical scan.
The horizontal should never stop like that. The vertical and horizontal scan should be dependent except for the fact they are synchronized together.
There should be a blanking pulse sent to the CRT cathode or grid to turn off the beam during retrace.
It does not seem the CRT is blanking much.
It is almost like the blanking pulse is being sent to the horizontal sweep section rather than to the CRT.
The blanking pulse comes from the vertical sweep section.
That would probably be a wiring mistake. Bad power supply filtering might allow the vertical sweep to effect the horizontal section.
It could be something else.
This similar to what was called "Christmas tree" sometimes caused by a bad cap in the horizontal oscillator circuit.
If you had an oscilloscope it would be easier to find which suspect is the guilty one.

Of course the signal thermistor would effect only about half the tubes. If I recall correctly Bob used two themistors in each string.

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 Post subject: Re: GE 805 "Locomotive" Restoration Help
PostPosted: Jan Sun 22, 2023 5:46 pm 
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Oh boy....

So,

The only wiring change I made (not sure if this would effect this) is at C7 a, b c.

Things are so tight in here I took the corresponding positive leads to their electrolytics. Then combined the negatives to one wire and ran it to the b- rail. These other wires attached to the old can mounting tabs I left in place. Did I screw up here?

Here are a few pics. Its also very difficult for me to jump between the riders and Sams I have moving forward. The component list and picture detail is much easier for me to read on the Sams. But anyways.

I do have a scope. It seems to work fine but I will tell you. I have no idea how to use it. It's something I'm really wanting to learn. Im sure walking me through this online will not be very easy....

Feel up to going down this rabbit hole with me? If not. I understand.

Thanks for all your time. Sincerely.


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 Post subject: Re: GE 805 "Locomotive" Restoration Help
PostPosted: Jan Sun 22, 2023 7:41 pm 
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gsxrkid74 wrote:
The only wiring change I made (not sure if this would effect this) is at C7 a, b c.

Things are so tight in here I took the corresponding positive leads to their electrolytics. Then combined the negatives to one wire and ran it to the b- rail. These other wires attached to the old can mounting tabs I left in place. Did I screw up here?

I would have connected that one negative wire to the old can mounting tabs. I don't have access to a schematic to see if that is B- or not. You could use your ohm meter to find out if those old mounting tabs are B- or not.

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 Post subject: Re: GE 805 "Locomotive" Restoration Help
PostPosted: Jan Sun 22, 2023 11:31 pm 
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Sure enough, both of those tabs run to the b-as well. Yes. could have done that. It's just so tight in there. I also was uncertain about those other wires interconnecting. It confuses me sometimes with electrolytic cans how they get their ground. They are often made of aluminum. Plus running to the b- instead of the chassis. I just wasn't sure the best approach. So me running the separate wire from these 3 lyrics ins't causing these issues in anyway correct?

Also, Here is the schematic (Sams) I've been using. No Time helped me out with the correct riders. For the most part they are the same. Everything I replaced on the set is what came out of it. The riders alpha/numerical system is a bit different and makes it hard for me. Anyways. I'm getting better with schematics. Slowly.

Unfortunately I'm at a standstill on this set with my limited knowledge. I need to do a few more voltage checks. What tubes should I check that could be a sign as to this vertical "Christmas Tree" effect I'm getting before moving on with the scope.

Hopefully you guys can slowly walk me through this.

Many Thanks.


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 Post subject: Re: GE 805 "Locomotive" Restoration Help
PostPosted: Jan Mon 23, 2023 1:18 am 
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gsxrkid74 wrote:
Oh boy....

So,

The only wiring change I made (not sure if this would effect this) is at C7 a, b c.

Here are a few pics. Its also very difficult for me to jump between the riders and Sams I have moving forward. The component list and picture detail is much easier for me to read on the Sams. But anyways.

I do have a scope. It seems to work fine but I will tell you. I have no idea how to use it. It's something I'm really wanting to learn. Im sure walking me through this online will not be very easy....


Well since I don't have the SAMS and it would be asking a lot for me to buy a copy just to help you it would really help me if you could refer to the part numbers as they are in Riders.
The picture of the SAMS schematic is too small to see the details like the part numbers.
What you did could be fine but I don't know at the moment.

So you have the scope just to impress dates, eh?
A scope can be extremely useful when working on a TV. Some get by without one but they really know how a TV works and are experienced noticing other clues to the problem.
You can get the approximate value of a DC voltage, the peak-to-peak value of a signal, the frequency of a signal and the signal shape among other things. That's just with one channel, with two channels like your scope you can see two signals at the same time, like the input and output of a stage.
Alan Wolke has at least two different videos on YouTube about scopes. One "Scopes for Dopes" is about
two hours long and goes into details like the history of oscilloscopes.
This one is half as long but touches on the important points.
https://www.youtube.com/watch?v=KYEMPm0c9kY

On a hot chassis set (like this one) you have to have a isolation transformer powering the TV or radio. That is because the ground of the scope probes is connected to the third (ground) of the power cord.
You will need to practice on some known signals. Don't look at the power line! A signal generator would be good because you can look at different frequencies. For starters looking at the output of a low voltage transformer (filament) would work.

When you can use the scope you will be able to look at the power supply voltages and see if there is a signal getting there from somewhere else. You can look at the sweep signals and see where they start to go wrong.
I feel like you have been asking me for a ride to places while all along you have a fully gassed up Mercedes in your garage.

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 Post subject: Re: GE 805 "Locomotive" Restoration Help
PostPosted: Jan Mon 23, 2023 2:27 am 
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No time,

It's more like I have the Mercedes but don't have a drivers license. I picked this scope up several months back at swap meet and have not leaned to use it yet. I will watch the video. I watched several video's back in the past and struggled. I do have ADD. I learn best when I'm hands on and have a chance to rinse and repeat. I realize to progress in this hobby I will need to learn using this. I also bought an isolation transformer. Again. Knowing in the future I would need it. I don't understand how I'm supposed to connect the ground clamp of the probe to the ground of the iso thou? Can you please explain.

Also,

Please know how much I appreciate the help from you guys. You've helped me restore three old TV sets and many antique radio's. I've been lucky in all aspects though because they all needed the minimal treatment of caps and out of spec resistors for the most part. All of which I learned from, but this is the first one that is really going to involve the key word in this realm. "Troubleshooting" and having the right equipment to do it. I am a slow learner. Thank you for being patient with me. This forum is the closest thing I have to a teacher. Aside from Youtube. I can watch videos until dawn and still struggle with UNDERSTANDING and RETAINING the provided information. I'm trying my best. Please don't give up on me!

Question. Am I at risk of damaging the CRT running this set while spending a lot of time voltage checking and learning to use the scope? I've seen where people use a dummy load.

PS. I feel like a dummy load....

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 Post subject: Re: GE 805 "Locomotive" Restoration Help
PostPosted: Jan Mon 23, 2023 3:06 am 
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Although that video covers a lot of ground, it doesn't always easily show what is going on. You kind of have to be there I suppose.
Alan has a channel on YouTube where he goes into more detail and since it is at his place the video shows things more close up. Some of the terms might be new to you but he knows what he is talking about.
Unfortunately he isn't specifically talking about TV circuits.
https://www.youtube.com/@w2aew/videos
You can do a search on his "Videos" page (scroll the horizontal bar at the top) for "scopes" and get more info on each topic.

You connect the ground lead on the scope probe in a similar way that you would connect the black lead on a voltmeter. You don't make any special connection to the iso transformer. Plug the TV into the isolation transformer and the scope into a regular outlet. A scope is like a voltmeter with a graphics display showing the voltage on a microsecond to microsecond basis.
That Tek 465 is a very well known and popular scope. High quality.
The only way to damage a scope is to put in too much voltage, so watch that. The 10X probe reduces that danger somewhat.

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 Post subject: Re: GE 805 "Locomotive" Restoration Help
PostPosted: Jan Tue 24, 2023 9:43 am 
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Someone mentioned Google for finding tube data sheets.

Here is the link to the definitive collection of datasheets for pretty much any tube that was ever made anywhere in the world, including CRTs.
Most tubes have several datasheets from various manufacturers. This can often be very useful.

https://frank.pocnet.net/

If it's not in here, it was never made!

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 Post subject: Re: GE 805 "Locomotive" Restoration Help
PostPosted: Jan Tue 24, 2023 6:34 pm 
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I just had a thought about the horizontal quitting and restarting when the vertical sweep retraces and what may be the problem.
Looking at the Riders schematic, I see that the vertical circuit gets it's power from the boosted B+ which is created by the horizontal output circuit. So the vertical retrace could put a pulse load on the horizontal.
Looking further I see that there is a filter cap in the vertical to supply the high current pulse so that the horizontal can just supply a steady state current. There may be a problem with that cap.
See if you can physically find C299 (Riders number) in the set. It would be connected to both the red wire of the vertical output transformer and a 1.5 K resistor (R303). It would be a 30 uf electrolytic cap. See if it has been replaced and if it is connected properly.

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 Post subject: Re: GE 805 "Locomotive" Restoration Help
PostPosted: Jan Wed 25, 2023 6:11 am 
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Thanks guys.

Tom,

I'm currently watching YouTube videos as Notime has forwarded to me in hopes of leaning to use my scope. I think this set is going to teach me a lot of valuable needed experience.

Yes. That cap has been replaced and is wired correctly. I think I'm going to try and spot check all the resistors in the set, or at least most of them. The only one's I replaced were on the focus board on top of the chassis below the CRT neck along with a large power resistor. My b+ is almost spot on, but I spot checked a few tube filaments and I'm getting some higher readings. I'm guessing some bad resistors?

So. here's some good news. I received a new damper tube (25W4GT) I had been waiting for yesterday. I figured since I replaced (19BG6G) I might as well pair it. Sure enough after pulling the old damper and looking close I noticed a one of the black plates has a ripple (like an open weld). Sure enough the crazy white vertical (Christmas tree) ripple is gone and the picture stability is improved. Although it is still somewhat jumpy and every once in a while it shows some really weird effects. I believe I have the ion trap set best as well as the focus coil. That focus coil design is primitive and frustrating to say the least imo. It also has horizontal white scan lines and a slow vertical dark band the moves up the screen regardless of adjustments. Its still overstretched horizontally as well. This video is as stable as Ive been able to get it.

https://youtu.be/IsafQYIYZsg

I don't want to drop too many eggs in one basket for you right now but here are a few things I need advise or opinions on.

1. I almost feel like I should have replaced ALL the tubes with NOS as a starting point. Or at least at this point. My tube tester has shown good emissions multiple times in the past only to find out they are bad with proper voltage applied to them. I have a pair of 12SN7GT's coming and the 6SL7GT. Most of the others have been replaced.

2. The CL90 I installed in series on one side of the filament voltage droppers. It seems to do nothing. Filaments light immediately and B+ didn't lose any voltage. I'm going to add another one to the other side if I installed this correctly. See picture above in my posts. Surely 200ohms (Cold) should create a soft start?

3. The sound. Low volume and high buzz. If I crank the contrast all the up or down and lose picture sync it restores the sound. (even though the speaker is trashed). Or if I turn it to channel 4 the sound is restored. I'm not sure where to tackle this when the time comes.

Lastly, I've ghosted through a lot of old threads on here with these locomotives. I'm told replacing the large Mica's in the horizontal and AFC will improve sync stability.

3900pf C96 and C102
1800pf C99
1000pf C101

Can I test Mica's with my fluke multi meter or should I just shotgun these out?

Sorry. I know I just threw a lot of questions in your lap.

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 Post subject: Re: GE 805 "Locomotive" Restoration Help
PostPosted: Jan Wed 25, 2023 4:27 pm 
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There are two separate filament strings. Sounds like you only added a thermistor to one string. So only some tubes will light up more slowly.

Either add one to the other side, or better yet, configure it to feed both sides. Put it between the common connection of the dropping resistors and AC line in other words.

These thermistors will have no impact on B+. That is a separate circuit.

BTW CL-90 is 120 cold , not 200.

You can check the mica caps values with your Fluke, but it will not put out enough voltage to properly test them for leakage.


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 Post subject: Re: GE 805 "Locomotive" Restoration Help
PostPosted: Jan Wed 25, 2023 5:30 pm 
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The dark band is caused by AC ripple getting into the video either by an open or miswired filter capacitor or a heater to cathode short in a tube. You can use the scope to check the plates of tubes in the video path for AC ripple with a stationary signal feeding the set or test the tubes again for shorts and check all the replaced capacitor wiring.

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 Post subject: Re: GE 805 "Locomotive" Restoration Help
PostPosted: Jan Wed 25, 2023 5:45 pm 
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Progress is always a good thing. Problems tend to get better in steps, there usually isn't one cause for all
problems.
The screen show a classic case of "hum bars", the 60Hz power line (since there are two bars here it actually would be 120Hz) is interacting with the vertical sweep which actually is 59.94Hz. The slight difference of frequency causes the bars to slowly move.
I'm afraid that points to a filter cap issue, I thought the filter cap issue was behind us.
The hum in the sound may also indicate a problem with the filter caps. The hum might also be related to the vertical sweep since the frequency is about the same you could not hear the difference.

The bright dashed lines you sometime see could be copy protection pulses some video sources have in the vertical retrace interval. They show up many times when the vertical sweep "rolls". You won't notice them if the sweep is locked in.

Problems with resisters and capacitors around a tube can effect the voltages around it, the filament voltage would not be effected however. A tube tester would find most problems a tube might have but not all of them. I usually say that you can go with a tube tester or a set of NOS tubes but shouldn't need to do both. If you do enough TV or radios many times you can accumulate a stock of tubes so you will have both.
Keep in mind that it happens that a bad component connected to a tube in some cases can damage a new tube.

I would not shotgun the mica caps. I typically shot gun the electrolytics and the paper caps, some people don't like to go that far.

There are books that you can download for free about using a scope, if I have time I might find the links.

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 Post subject: Re: GE 805 "Locomotive" Restoration Help
PostPosted: Jan Wed 25, 2023 6:04 pm 
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If I had a filter capacitor wired wrong wouldn't it go bang bang?

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 Post subject: Re: GE 805 "Locomotive" Restoration Help
PostPosted: Jan Wed 25, 2023 8:00 pm 
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If it was backward, or it couldn't handle the voltage. Sometimes they would just vent without exploding.
You could have the capacitance values switched around or not wired right.

I came across one book. It goes into a lot of detail about the circuits in the scope, but it does cover some good info on probes and some of the control settings.
Not so much on using a scope.
About half way down the page. "Know Your Oscilloscope" 1980.
https://worldradiohistory.com/BOOKSHELF ... f_Sams.htm

The earlier edition cover tube oscilloscopes that don't work like your triggered 465.

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 Post subject: Re: GE 805 "Locomotive" Restoration Help
PostPosted: Jan Wed 25, 2023 8:25 pm 
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Ok thank you. When I get home tonight I am going to start by triple checking my lytics in the power supply.

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