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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Fri 11, 2019 5:42 pm 
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Joined: Sep Thu 20, 2018 8:53 pm
Posts: 111
Quote:
I guess you typed R7 where you meant V7 a couple of places. Also I think you meant C1B where you had C2B.

Yes, sorry.

I did have it running good yet after putting all the tubes back in as I recorded one of the videos after that point. However I should note that after cleaning the socket contacts with D5 I initially turned it on soon after, as the instructions suggested only needing to wait several minutes. But then I read other posts here and elsewhere that said to wait even a couple days to start it as otherwise the socket contacts could short.. Again it was working successfully after that point and after I had waited 2 days to try it again. I suppose there isn't any good way to determine if a socket is bad; I did verify strong continuity from socket to trace.

This weekend i will verify all tube placement and try swapping the ones I have two of. I also have a new V7 tube coming next week and hope to get a mutual conductance tube tester at some point. I'll also attempt to note the voltages of all tube socket pins at 117V since I've still only checked V7. I'll also check over the caps.

Yes, all paper and electrolytic caps have been replaced. I didnt do anything with mica or ceramic ones.

Also I have been going through the excellent scope tutorials shared here on YouTube. I find some aspects difficult to follow or compare as I dont have a signal generator. I was wondering if I could output audio signals from an old electronic keyboard and use that as a signal generator rather than investing in a $100 device. I think testing the scope with a known signal would be helpful for me to understand the functions.

Can someone clarify the schematic meanings for the wave patterns? There are some numbers and values given next to each image.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Fri 11, 2019 11:39 pm 
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Location: Dallas, TX
There shouldn't be much trouble finding a signal source to look at on the scope. Musical instruments seldom put out a sinewave because it turns out sinewaves don't sound very good. Also it would be good if the signal was continuous and without effects like vibrato or tremolo. I don't know if the output is a sinewave but your 1077B is supposed to put out a 1 KHz signal.
Yep, the numbers by the SAMS waveforms do take a little explaining. Modern scopes have triggered horizontal sweeps that are also calibrated in time per screen division. Back when this TV was made almost no one except scientists and other researchers had triggered scopes. The repair shop scopes had continually running sweeps that you could adjust for speed (frequency of the scanning sawtooth) and they were not calibrated well. Basically you would adjust the horizontal sweep until the trace was stable and showed the number of cycles you wanted. SAMS for instance indicated 30 cps on some of the images, meaning the horizontal scope sweep repeated at 30 Hz. Since the vertical TV sweep is 60 Hz, you see two vertical cycles per scope sweep. Other placed SAMS shows 7875 cps which is half the horizontal frequency of 15750 Hz, so you see two cycles of the TV horizontal sweep. On a modern scope you could set the sweep rate to 5 ms/div for the vertical rate and 10 or 20 us/div. for the horizontal. You could not get exactly the same look though unless you clicked off the calibrated rate and adjust the variable knob because the numbers otherwise don't give exactly two cycles.
Which scope tutorials di you look at, people have different ways of explaining things.
For fun, there was a guy that had a TV show back about when you TV was made, Erie Kovacs. He used the image from an oscilloscope, that was hooked up to the sound from a record, as a separator between sketches sometimes.
https://www.youtube.com/watch?v=hfB3jj8vKlo

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Sat 12, 2019 11:04 am 
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matt it is the vertical multivibrator part of the v7 tube that is giving you a problem with voltages being high right? try injecting at the grid of the vertical output tube with your tv analyst and note if there is any change in the picture. i would say disconnect the coupling cap from the grid of the vertical output tube to isolate it from the suspected problem v7. the book you bought will tell you how to inject the signal. i have a feeling since one output is working all outputs on your 1077 are working. if the distortion in the pic goes away when you inject the vertical signal your problem is indeed in v7 or associated components. if the distortion doesnt go away it is coming from some other section not v7. this is the beauty of the tv analyst you can go stage by stage through the whole tv till your problem is located.

i still say check all components associated with the pins where voltage readings are off. this troubles me how readings can be off so much when a signal is applied. is it possible there is a note in the voltage chart saying readings taken with no signal applied. check the sams voltage chart to see if there are any special instructions for taking the reading. if for instance it says taken with a volt meter 20000 ohms per volt you can not use a modern meter to take the measurement as your readings will all be high. this is because a modern meters will not load the circuit down the way a meter back in the day would. if it says readings taken with a vtvm it should be ok to use ur dmm or the vtvm i sent you. check for any notes about special conditions for the test.

your idea for swaping tubes with the same tube type in a different position im the set is standard troubleshooting procedure and is a good idea.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Sat 12, 2019 12:11 pm 
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Thank you all! I will be working on some of these new suggestions and advice this weekend and some responses are below. I also have new updates to share from another evening of experimenting, which can hopefully further pinpoint the really bad video/audio issue (including a brand new video/audio demo):

Review of Sync Board Components - I started double-checking all of the new caps I put on and other components on the sync board while also checking over the trace paths to ensure no obstructions or lifts. To make it easier, I annotated the SAMs photo diagram and made matching spreadsheets to check off the resistors and capacitors as I go along. I have fully verified all new caps on the sync board, some required removing one lead from the circuit as recommended but then were very accurate to the specs. I did not check the mica/ceramic ones yet.

Temporary Redo of C1B - Although I was confident this had nothing to do with it, earlier this week I noticed the positive lead of this electrolytic had not been well attached. I found this out after inadvertently applying slight pressure in which the lead came undone and the video became a scrambled mess of snowflakes until reconnected. To rule this out as having any relation to the main video/audio issue now experienced, I used a new electrolytic and temporarily ran it under the chassis to a different common ground point - it neither worsened nor improved the video glitching.

The 8XP4 Test Tube - I notice that the 8XP4 has some loose sounding materials inside that you can hear when it is tilted, just like a burned out incandescent bulb. I mention this as build-up for the next highlight, as I wanted to rule out the test CRT as possibly being a culprit since it is the only CRT I have ever tested with the chassis ever since the original went out.

The new 21ATPL4 CRT - I decided that the best way to rule out the test CRT as a contributing factor to the issue was to power it up for the first time using the brand new CRT that I had previously mounted into the cabinet. After getting everything temporarily fixed behind the cabinet as I used to when testing, I powered it on with all connected for the first time. I had put the adjustable Ion Trap I purchased on the neck of the tube. However, I got no video output at all even though the CRT was it up nicely. That was when I did more research and found some other threads on these forums where the particulars of ion trap positioning were mentioned. So I went back and slowly started rotating and sliding the ion trap along the neck. It was a great feeling when it finally wound up positioned correctly and the screen lit up! This is an adjustable ion trap so I can alter the gauss by turning a screw but got it to an acceptable state just for this test.

What the New CRT Shows - Hooking it to the actual CRT helps to emphasize the visual and audio interference-type problem (that still persists). With the new CRT running and the 1077 outputting the 1K audio and test strip to it, I was able to review the circumstances more meticulously. The sound and video are still distorted as they were. If I turn the brightness completely down the audio becomes clear and interference subsides. Conversely, as I turn the brightness up an increasingly high pitched screeching frequency emits from the speaker (sounding much like a stock car revving its engine). So there is a clear and definite correlation between the audio and video glitching out and it is impacted 1:1 based on brightness.

Here is a video I made from the new CRT that demonstrates all of this perfectly (with audio tone from 1077 and adjusting the brightness). It does feel as if too much voltage is being let through and not being resisted.

Video: https://www.youtube.com/watch?v=01jKpLKz37o

Quote:
is it possible there is a note in the voltage chart saying readings taken with no signal applied.

Yes, actually it does and I completely forgot about it previously. In the information box of the schematic it specifically states the following:

1. DC voltage measurements taken with vacuum tube voltmeter; AC voltage measured at 1,000 ohms per volt.
2. Pin numbers are counted in a clockwise direction on bottom of socket.
3. Measured values are from socket pin to common negative unless otherwise stated.
4. Line voltage maintained at 117 volts for voltage readings.
5. All controls set for normal operation; no signal applied.

So I will definitely always check voltage without a signal running through it from here on out and use a 117V collaborated variac.

@Notimetolooz, I started going through the ones you recommended which was the same channel I had found initially and walked through one of the first primer videos when I was first testing if my scope worked. I also have found that it is possible to generate sine waves and other signal sounds from the computer (such as from this website) and then by running an audio out cable from the headphone jack to the scope probe I'm able to view signals on it enough that I should at least be able to follow along more readily when learning about the numerous controls. I did not replace any parts of the oscilliscope since receiving it but it does seem to be working very well with a nice bright display.

Attached are some photos as well (taken from the video). Notice that as the brightness increases, so too does the number of horizontal lines going through it. When on very low brightness, only a few of these lines appear.

I think the greatest news out of this update post is that I have now verified the new picture tube is excellent and functional, the ion trap I got works great with it, and therefore if I can just resolve these video and audio glitches there is nothing major stopping this from being a like-new working set again!


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File comment: Admiral Annotated Sync Board Diagram
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File comment: Admiral CRT on Low Brightness
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File comment: Admiral CRT on High Brightness
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File comment: Admiral CRT on Very Low Brightness
Admiral-Really-Low-Brightness.JPG
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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Sat 12, 2019 1:12 pm 
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Location: Belrose, NSW, Australia
Make sure the aquadag on the CRT is grounded to the chassis. There should be a spring loaded wire stretched across the dag on the bulb of the CRT. This should be reliably grounded to the chassis.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Sat 12, 2019 6:20 pm 
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Irob2345,that's a good point about the aquadag grounding, something that isn't obvious for someone new to the subject. It does almost sounds like an arcing that changes with load. I wonder if there is a voltage breakdown somewhere in the HV section?

It seems to me that the problem could be some sort of oscillation that changes as a result of a voltage change that itself is varied by the load of the picture. The oscillation is getting into the video and sound. I also noticed that the vertical sweep changes a bit, either size or centering. The brightness control is fed by that 150V line.

It will be nice when the current problem is dealt with and the only remaining one is with the vertical sweep.
I think that besides the vertical roll there is a problem that is causing the bottom of the picture to be cut off.
By adjusting the vertical linearity way off the cut off was minimized, but that isn't a good fix.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Sat 12, 2019 10:34 pm 
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I'm sure that it's an HV issue. If there is a resistor in series with the HV lead that can go O/C and cause this. As can a bad connection on the lead.

I've also seen a bad contact inside the CRT from the ultor connector to the gun behave like this. Not much you can do if so...

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Sun 13, 2019 12:12 am 
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just a few observations. since voltages on v7 seem ok with no signal and the service notes say voltages tested with no signal forget v7 for now.

this does look like a high voltage section problem. since the brightness control has an effect on the problem i would say the problem would be located between the brightness control and the input to the high voltage section. the book you have on your tv analyst will tell you step by step how to troubleshoot the high voltage section.

an easy thing that can be done is substitute the tubes in the high voltage section one at a time turning on the set after each tube is changed and note any change in the picture sound issue. this will rule out a bad tube. if indeed the last tube changed clears the issue then you have it fixed. this may not fix the problem but will rule out a bad tube and is the easiest thing to test first. start with the simple possibility then move on to more detailed troubleshooting. if indeed a tube has an oscillation in it this just could fix it when the tube is changed. a tube that has grid emssion can cause weird problems.

do indeed check resistors and caps in the high voltage circuit and check for bad connections. i remember reading that mica caps are going bad in the high voltage section also.

re aquadag coating: since you are testing the chassis outside the tv i would think a clip lead can be run from the spring around the crt to a ground point on the chassis to test if that changes anything. aquadag is the black coating on the bell of the crt. there is a metal spring that goes around that and is grounded to the chassis.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Sun 13, 2019 4:41 am 
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Quote:
Make sure the aquadag on the CRT is grounded to the chassis.


I will probably need more explanation of this when I get to putting the chassis in for real. Here are photos of the CRT as mounted; it has the metal bracket/brace around all sides and then another near the front. The chassis has one wire coming out of it that I don't recall what it is for. See screenshots.

Today I found that the anode lead end into HV Rect was so brittle and loose it broke off! So I redid that but cut back a little further to where the wire seems more structural; I am still using a NOS piece of high voltage anode wire. I also replaced the connected 5.1Ω resistor in HV Rect with a brand new 1.8+3.3 series equivalent, although after removing the old it still tests fine (as I determined the first time I worked at this area). The one that had been used there was a 2W although the specs only call for 1/2W (which my new ones are). I had hopes this could've possibly helped video/audio spasm issue, but it didn't seem to.

When I first power up the set there is a sort of rush of loud static from the speakers while the CRT is still warming up and coming into focus.

Also this issue (including with the brightness variance) occurs on the test tube as well as the real CRT. The test tube does not have any coating on it or require grounding.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Sun 13, 2019 6:18 am 
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HV Culprit Discovered!

After posting last, I continued exploring possible causes centering around the HV area. I tried replacing the HV Rect and Horiz. Output tubes with second ones I had from the original set. That did not help.

I felt after redoing the HV lead wire earlier that it didn't seem as badly distorted when I first tried, but then soon returned to its glitching. So I examined the HV rect socket more carefully. Everything seems well connected. However, the anode lead itself OR the socket pin it connects to appear to have a short or something loose. When I pull the wire snug to the left (from the front) suddenly all of these new audio and video glitches go away and the video clears right up! Letting it go and it returns to the same trouble.

So my next task is to actually find out more specifically if it is the wire or the socket prongs it connects to (pin 2+7). I do have a "high voltage lead splice" kit on the anode wire that I mentioned months ago but it has never given me any trouble. So I'm leaning more to it being something loose in the pins... Still, the responsible issue has been found so once I address this we should be back to the vertical roll issue as the main concern.

You guys were spot on about it being in the HV area. I was chasing false leads before this, believing that it directly stemmed from the sync board or resistor I had recently replaced. 8)

Edit: I found it stems from the anode cap area that goes into the CRT. This is the original cap and wire part from the Admiral. If I apply slight pressure to the left directly near the base where it is in CRT then everything clears right up.

Edit 2: It actually appears that the entire cap that goes into CRT is simply so rigid and aged that it cannot keep a solid contact with the CRT so is leaking and that is what is causing the trouble.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Sun 13, 2019 7:33 am 
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ok your latest findings sugests there might be a loose connection between the wire and the part that goes into the crt or the part that goes into the crt might not be making good connection to the crt. check the joint where the wire connects to the part that goes into the crt. if all is ok check that the part that goes into the crt is making good contact. that was good detective work tracking that down. might be a good idea to eliminate the old wire and connect your new 2nd anode lead direct to the part that goes into the crt. with the test tube now u can use that for troubleshooting purposes.

re the piece of wire sticking up from the chassis: yes that is probably how the aquadag coating on the crt is grounded to the chassis. it looks like one end is soldered direct to the chassis and the other end would stick up and touch the aquadag on the crt.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Sun 13, 2019 8:39 am 
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Quote:
or the part that goes into the crt might not be making good connection to the crt.

It is definitely this. I have found that when the plug is in the CRT it simply does not hold strong connection anymore. So you wind up with "hissing" sounds coming from the plug and this is what leads to the lost volts and problems.

Way back when I got the new 2nd anode lead I attempted to use that directly, but the end plug from the new one to the CRT was too buoyant to stay put so would always pop right out. I just tested that end with the test CRT and the new CRT and it exhibits the same symptoms so doesn't stay. Months ago I cut the end off of the new wire and then spliced the wiring onto the original wire/end but now it is that original end that is exhibiting poor connectivity.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Sun 13, 2019 2:09 pm 
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can you spread the metal piece that goes into the hole of the crt out a little bit so it would make better contact. this is what holds it in place not the rubber part. make sure you discharge the crt before removing the 2nd anode lead. you dont want to get bit.

another posibility is if the origional metal part that goes into the crt hole is oxidized you could try cleaning it with fine sand paper clean off anything left by the sand paper then see if it makes better contact to the crt.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Sun 13, 2019 3:28 pm 
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It is kind of odd that you had the same problem with the 8 inch substitute CRT, you probably didn't have the exterior aquadag connected either. Maybe the smaller CRT does not have an exterior coating.
To explain things a bit. Aquadag is carbon powder in a water based mixture that also contains a substance that helps it stick to glass. It isn't as strong a bond as paint. The inside of the CRT "bell" is coated with aquadag and is in contact with the HV second anode connection. Because of the carbon aquadag is conductive. The inside coating provides acts to collect the current from the electron beam, it also electrically shields the beam from outside electronic fields. Early CRT did not have a exterior aquadag coating. The HV needs to be filtered to smooth it out after the HV rectifier and the early sets had one or two high voltage capacitors with one end grounded. Later an exterior aquadag coating was added to the exterior of the CRT bell and grounded. The glass of the CRT acts as the dialectric (insulator) of a HV cap. That CRT capacitor is why you have to discharge the anode of the CRT before you work on it.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Sun 13, 2019 10:55 pm 
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Quote:
It is kind of odd that you had the same problem with the 8 inch substitute CRT, you probably didn't have the exterior aquadag connected either. Maybe the smaller CRT does not have an exterior coating.


Thanks for the added explanation. Yes, on the Sylvania 8XP4 test CRT the instruction guide specifically notes:

Quote:
NO EXTERNAL CONDUCTIVE COATING

As a safety feature and to make the tube universal, no external conductive coating is used. This eliminates the necessity for "discharging" the tube before handling, and is a time saver in a tube which is to be repeatedly installed and removed in its application. Although seldom necessary, if desired, an external capacitor may be employed to duplicate the coating capacitance of any regular picture tube.


But as I mentioned before it definitely seems to be a bad anode cup that is causing such leakage and short-like behavior. I checked with my high voltage lead and when the problem is acting up there are more than 2,000 volts escaping.

Quote:
can you spread the metal piece that goes into the hole of the crt out a little bit so it would make better contact.

I have tried this a little already to no benefit. However I will keep experimenting since I find the problem is less prevalent depending on its rotation when inserted, so certain parts of it seem more firm than others. I wish I had kept the old parts of the original non-working portable 21" Admiral I was unable to fix, since I bet the anode lead of that would've been easily compatible.

Quote:
another posibility is if the origional metal part that goes into the crt hole is oxidized you could try cleaning it with fine sand paper clean off anything left by the sand paper then see if it makes better contact to the crt.

I'll try this as well, thanks. Might this be a good application to apply some D5 contact cleaner as well? I did try cleaning it a bit with isopropyl alcohol already.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Sun 13, 2019 11:15 pm 
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MattPilz wrote:
Quote:

Quote:
another posibility is if the origional metal part that goes into the crt hole is oxidized you could try cleaning it with fine sand paper clean off anything left by the sand paper then see if it makes better contact to the crt.

I'll try this as well, thanks. Might this be a good application to apply some D5 contact cleaner as well? I did try cleaning it a bit with isopropyl alcohol already.

It definitely does seem the connector is at fault, I meant it was unfortunate as far as troubleshooting that the different tube didn't show a difference. I suppose the tube hole/well are identical in the two tubes.
Cleaning the connection probably wouldn't help much since loosing a dozen volts wouldn't mean much here.
The problem is definitely the loss of the spring pressure of the metal fingers and the flexibility of the rubber boot. If you don't have a better connector you might try to make a rubber "donut" to put under the boot so that there is more tension on the connection.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Mon 14, 2019 12:09 am 
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matt clean any dirt grease etc off the crt around the hole where the 2nd anode lead goes. unlikely it will help but cant hurt. dont stick your finger in the hole. dont ask me how i know that its embarasing but i do. even after it is discharged a crt can build up a voltage in it.

one possibility if you see a solid stage crt television being thrown out cut off the 2nd anode lead and use that connector to attach to your 2nd annode cable. dont know about where you live but crt televisions show up on the curb around here periodically on garbage day. i dont think the connector for the 2nd annode lead changed any over the years but never having worked on a solid state tv or taken one apart im not positive.

indeed the 2nd anode lead cap you have that just pops off you have to increse the spring tention. do you have a pic of the part of that cap that goes in the crt hole. if so post it. some had like two legs bent at a right angle that went in the crt hole. should be easy to increse tention on this type. others had like a round metal circle that pluged in the hole. this might be a bit harder to expand.. i saw a guy make a test lead for the second anode and he used a safty pin for the 2nd anode lead connection to the crt. not sure if this would be safe as a permanent fix. kind of doubt it.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Mon 14, 2019 6:31 am 
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HV Issues Corrected!

Based on Thomas' suggestion of finding another 2nd anode lead from a parts set, I recalled that I had an early-90s Zenith console in my shed with various picture tube issues that someone planned to dump. I opened it up to find a nice 24-36" anode lead of same specifications as the original in Admiral (40KV 105' rating). The rubber shoe is in pristine condition and this style uses just two metal hooks to more tightly latch into the anode CRT port than the original. After verifying that it fit snug into the test CRT I cut it off and replaced the bad one on the Admiral with it.

Now the HV lead is working perfectly again with no surging or voltage issues and none of the video/audio glitches. It has a tight suction around the CRT with the larger rubber shoe. So I am now back to being able to focus on the vertical roll issue. This week I will attempt construction of a new 'M7' after getting some boards to make it on. I will also continue reviewing and testing the different resistors and components on the sync board.

You can see the differences between the original well-worn end and the new one below!

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Yoke Wiring Question

I think I have this correct (obviously the yoke seems to be functioning fine) but want to still clarify...

The new yoke that I had purchased came with four wires preinstalled, while the Admiral schematic calls for five. It is noted as an exact replacement in the SAMs schematic (Thordarson Y-16) with the footnote in SAMs: "Use original horizontal damping network." Here is the schematic comparison between the SAMs 20Y4E schematic (left) and the Y-16 (right).

Attachment:
1ChtRKb.png
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The Y-16 instructions note:

Quote:
When replacing yokes with 5 leads it will be necessary to remove the fifth lead from the original yoke and connect it to the same electrical point on the Y-16. This is easily accomplished by disconnecting the 5th lead from the old yoke, removing the rear cover from the Y-16 and reconnecting the lead to the same lug. Feed this wire through the same hole as the other leads and replace the rear cover. The largest percentage of 5 leaded yokes will have pin numbers exactly like the Y-16 thus making this connection a simple matter of removing the lead, usually from pin 5 or 8, and reconnecting it to pin 5 or 8 on the Y-16. In a few cases, however, pin numbers may not be the same and it will be necessary to note the electrical connection of the original lead and connect it to the same electrical point on the Y-16.


I have had some uncertainty over this fifth wire and its purpose when looking at the schematic. I have actually used the yoke with and without it connected and was not quite clear what if any differences were occurring as the picture came in regardless. The current socket pin assignment is assigned as follows:

Black - Pin 1
(New Wire / Orange) - Pin 3
Red - Pin 5
Green - Pin 7
Yellow - Pin 9

Attachment:
Color-Yoke.jpg
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Originally when I had it hooked up the horizontal was inverted but I corrected it based on the pin arrangement above. Looking at the top of the yoke down, this is a rough diagram of the pin arrangement as I have it.


Attachment:
Yioke Overhead.jpg
Yioke Overhead.jpg [ 128.17 KiB | Viewed 1283 times ]


I wired the 5th to pin 2 which based on the schematic should be correct, agreed? Pin 2 on the yoke had nothing attached except one of the fine wires from a coil. I think my concern just stems from the instructions suggesting pin 5 and 8 is most common to apply it to.

Here is one more of the schematic:

Attachment:
Yoke-2.JPG
Yoke-2.JPG [ 340.1 KiB | Viewed 1283 times ]


QUESTION 1: Does pin 2 of the yoke appear correct to attach the new wire to?

QUESTION 2: Can anyone explain why the new yoke has a capacitor across one half of the horizontal coils, but the original did not?

QUESTION 3: Any further explanation as to what this fifth wire addition actually achieves? It seems it might just feed a little more resistance into that coil?


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Mon 14, 2019 7:39 am 
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Joined: Jun Thu 25, 2015 3:21 am
Posts: 1352
good news with the high voltage lead. im glad you got it fixed. dont throw out the old one as the wire is still good and can be used if you ever need to just not the part that goes into the crt. they do have rubber renew products that may soften up the origional rubber boot to the point it may work.


Last edited by thomas13202 on Oct Mon 14, 2019 8:24 am, edited 1 time in total.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Mon 14, 2019 8:16 am 
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Joined: Jun Thu 25, 2015 3:21 am
Posts: 1352
if the origional yoke is working why change it? dont fix what isnt broke. whether it is the origional or the replacement yoke you are using i dont know but i dont see any problems you are having that would be caused by the yoke. since its working leave it alone is my advice.


re wireing of the yoke. some yoke wiring went to a plug that would then plug into the chassis. the schematic of the yoke seems to show this. sometimes they were hard wired to a terminal strip
the only wiring you would have to change is run a wire from pin 2 on the yoke to pin 3 on the plug that goes to the chassis. then connect the other wires exactly as the origional yoke.

in the four wire version both horizontal coils are wired in series between pin 1 and pin 5 on the plug. what the fifth wire does is change that to a series parallel circuit. one of the horizontal coils is wired in parallel between pin 3 and pin 5 and is still in series with the other horizontal coil between pin 1 and pin 5. i am no engineer so i couldnt explain exactly what efect that would have on the picture.

the pin out you posted for the yoke is correct.


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