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 Post subject: Re: Getting started on Admiral 19F1
PostPosted: Aug Fri 16, 2019 5:37 pm 
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Joined: Feb Wed 03, 2016 9:11 pm
Posts: 68
Location: Savannah, GA
Those BK 1077B's seem to be pretty affordable. What are the chances of them needed calibration after purchase as most being sold on eBay are "untested"?


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 Post subject: Re: Getting started on Admiral 19F1
PostPosted: Aug Fri 16, 2019 7:10 pm 
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Joined: May Thu 14, 2015 4:15 pm
Posts: 2342
Location: Dallas, TX
FYI.
B&K made a series of similar models through the years. The first version was just called Dynascan, then models 1075, 1076, 1077 and 1077B. The earliest are all tube bases while the last is mostly solid state.
I have a 1075 that I will restore some day, I did repaint the case. Even the newest version is probably old enough to need the electrolytics replaced at the minimum.
Do a search on the forum here and at Videokarma on the units.

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Tim
It's not the Destination, It's the Journey.


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 Post subject: Re: Getting started on Admiral 19F1
PostPosted: Aug Fri 16, 2019 7:35 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Woodinville, WA USA
I replaced the electrolytics on my 1077B and made a couple of basic adjustments such as centering the image.

Regards,

Phil Nelson
Phil’s Old Radios
https://antiqueradio.org/index.html


Last edited by philsoldradios on Dec Mon 16, 2019 3:36 am, edited 1 time in total.

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 Post subject: Re: Getting started on Admiral 19F1
PostPosted: Aug Fri 16, 2019 7:46 pm 
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Joined: Nov Thu 11, 2010 6:03 pm
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Location: Pewaukee, WI
Personally if I prefer electronic test pattern generators for setting linearity, centering, convergence and the like. I also have made a test pattern DVD for when I want to broadcast a pattern to one or more sets and not have to lug a spaghetti box around.

The Analysts use a flying spot scanner that while it can be set up to be accurate is fundamentally less stable as well as heavier and bulkier than other devices. They shine in all different types of hard troubleshooting that you are going to do on your workbench, but lack that " bring it to any set anywhere in the house" mobility of a dedicated solid state pattern generator.


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 Post subject: Re: Getting started on Admiral 19F1
PostPosted: Aug Sat 17, 2019 1:08 am 
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Joined: Aug Thu 12, 2010 6:25 pm
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Location: Durham, NC
Electronic Memory wrote:
Personally if I prefer electronic test pattern generators for setting linearity, centering, convergence and the like. I also have made a test pattern DVD for when I want to broadcast a pattern to one or more sets and not have to lug a spaghetti box around.

The Analysts use a flying spot scanner that while it can be set up to be accurate is fundamentally less stable as well as heavier and bulkier than other devices. They shine in all different types of hard troubleshooting that you are going to do on your workbench, but lack that " bring it to any set anywhere in the house" mobility of a dedicated solid state pattern generator.


Yes, they are monumentally heavy! But cool.

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Mark Nelson
A collector of TV signal boosters and UHF converters -- God help me!
tv-boxes.com


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 Post subject: Re: Getting started on Admiral 19F1
PostPosted: Nov Sat 16, 2019 9:48 pm 
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Joined: Feb Wed 03, 2016 9:11 pm
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Location: Savannah, GA
Good afternoon all, this set has been finished and been in use for a few months now, and this morning upon powering it up I was met with an empty screen. I was watching it last night for several hours without any issues. Despite the empty screen audio was coming through just fine, high voltage was present, and the ion trap was properly adjusted. Nothing had been changed since last night. After I checked the H.V. and ion trap I removed the chassis. I tried swapping each of the H.V. and horizontal section tubes, checked the flyback, and B+. I then noticed that I can get a partial picture with the brightness control adjusted to about 12 o' clock, but if I move the control either way from that position the picture disappears. At this point I removed the brightness control to clean and test it. It tested fine. I am stumped. It certainly seems that it could be the brightness control at fault, but it measured just fine.


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 Post subject: Re: Getting started on Admiral 19F1
PostPosted: Nov Mon 18, 2019 5:02 am 
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Joined: Nov Thu 11, 2010 6:03 pm
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Location: Pewaukee, WI
Check bias at the CRT base while varying the control and also measure HV while adjusting the control HV voltage should not vary from schematic value more than 2KV.


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 Post subject: Re: Getting started on Admiral 19F1
PostPosted: Nov Thu 21, 2019 9:10 pm 
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Location: Savannah, GA
I am not familiar with checking the bias on a CRT. How would I go about this?


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 Post subject: Re: Getting started on Admiral 19F1
PostPosted: Nov Thu 21, 2019 10:20 pm 
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Location: Pewaukee, WI
The schematic should list cathode and grid voltage with reference to the chassis compare measurements to schematic values and look for anomalies. It may also be helpful to measure cathode-grid voltage difference...The grid should be negative relative to the Cathode but not too negative and you should be able to approach a 0V difference between the two.


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 Post subject: Re: Getting started on Admiral 19F1
PostPosted: Dec Fri 13, 2019 4:27 pm 
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Location: Savannah, GA
The grid looks to be the suspect here. It is running about 120V lower than the schematic value, and does not vary with the adjustment of controls. Possible causes?


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 Post subject: Re: Getting started on Admiral 19F1
PostPosted: Dec Sat 14, 2019 12:14 am 
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The grid (pin 2 of the CRT) shouldn't change with any control setting - it's only supplying a vertical pulse for blanking. The brightness control should vary the cathode (pin 1) voltage, though. My schematic (Beitman) indicates it should be about +25V (referenced to chassis) in normal operation.

If the grid is indeed -120V or so then the wiring and components (including the picture tube socket) between vertical output transformer and CRT grid should be checked.

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A collector of TV signal boosters and UHF converters -- God help me!
tv-boxes.com


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 Post subject: Re: Getting started on Admiral 19F1
PostPosted: Dec Sun 15, 2019 11:45 pm 
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Joined: Feb Wed 03, 2016 9:11 pm
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Location: Savannah, GA
I have checked through the components mentioned above. The only issue I was able to find was the plate voltage on the 6S4 vertical output tube. The schematic value has 440, but it was sitting around 350. All other components appear fine including the vertical output transformer. I am a little confused on what is supplying the 6S4 plate voltage, and therefore unsure where to look for the cause of the low voltage. Could this be related to the low grid voltage of the CRT?


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 Post subject: Re: Getting started on Admiral 19F1
PostPosted: Dec Mon 16, 2019 3:48 am 
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Location: Durham, NC
The 6S4 plate voltage is variable depending on control settings (according to my Beitman schematic), probably mostly by adjusting the Vertical Linearity pot. It's possible that 350V is within range of that control.

The 6S4 plate voltage is applied at the center tap of the vertical output transformer, and it's called the "boost" voltage since it comes from the horizontal output transformer and the damper tube, which boosts the 265V main plate supply. I admit to not understanding how exactly this is achieved (I've read explanations but they never stick with me).

There is no DC connection (or there isn't supposed to be) to the grid of the CRT -- just a 56K in parallel with a .01uF to ground. The vertical pulse from the vertical yoke is AC coupled to the grid through a .01uF. If you have a big negative voltage on the grid then there's something weird going on. Are you measuring at pin 2 of the CRT, or somewhere else? It occurs to me that an open wire, bad solder joint or bad socket could perhaps make the grid float. Grounding pin 2 of the CRT should make the picture reappear if all else is working.

I hope some folks with more practical experience than me can weigh in.

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Mark Nelson
A collector of TV signal boosters and UHF converters -- God help me!
tv-boxes.com


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 Post subject: Re: Getting started on Admiral 19F1
PostPosted: Dec Mon 16, 2019 10:00 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 351
Location: Elkhorn,Wisconsin,United States
Hi,
Just to note, the first 3 production runs of the 19F1 do not have a vertical blanking circuit. CRT grid one( pin 2) should be grounded then. Production run 4 and up used the blanking circuit. CRT grid 2 (pin 10) should have a B+ voltage of 450 or greater. Pin 10's boost voltage should not vary, it should remain relatively constant.
Did you check for a video signal at crt ( pin 11) cathode with your oscilloscope? Like AJX2 mentioned, crt cathode (pin 1) should have a DC voltage that varies with the brightness control setting. I'm assuming you no longer have a raster on your crt screen. What did you mean by a partial picture, a raster or an image ? Could you post a picture of the partial image. With a boost voltage reading so low something may have happen with the vertical or horizontal sections. I assume you replaced all the paper and electrolytic caps in August.
Ed


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 Post subject: Re: Getting started on Admiral 19F1
PostPosted: Dec Wed 18, 2019 2:57 am 
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Joined: Feb Wed 03, 2016 9:11 pm
Posts: 68
Location: Savannah, GA
Alright, here's what I have. The CRT cathode (pin 11) seems to be operating normally. It varies from about 0-100 volts as I adjust the brightness control. The grid (pin 2) looks to have a solid ground connection and reads right around zero. The anode (pin 10) looks to be the issue. It is sitting around 350 volts where as the schematic calls for 470. I have also checked the voltage between the cathode and grid which measured to be -13. The "partial picture" I mentioned previously is a full picture that occurs at a very specific spot on the brightness control, right around 12 O' clock. No picture or raster is displayed except for when the brightness control is in this specific position. I have checked to see if the voltages differ any while the brightness control is at this position, but they remain the same. I can't seem to find any faulty components or wiring either. As I said, this set was functioning just fine one night, and when I powered it up the next day this problem occurred from the get go.



Also, I did not know that about the runs of 19F1. Mine appears to be run 8.


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 Post subject: Re: Getting started on Admiral 19F1
PostPosted: Dec Wed 18, 2019 4:06 pm 
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Joined: Jun Mon 24, 2013 3:00 pm
Posts: 1522
Location: Champaign IL 61822
I've got three HV probes. Printed resistances vary: one is 200 Megohm, one 730 Megohm,
one 2.145 Gigohm. Checked by measuring current through them from a precision 5kV
lab supply all three are, despite being quite old, within 1% of the printed value.

All the probes that look like in the picture open up and you can look for the resistor value.


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 Post subject: Re: Getting started on Admiral 19F1
PostPosted: Dec Wed 18, 2019 4:16 pm 
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Joined: Jun Mon 24, 2013 3:00 pm
Posts: 1522
Location: Champaign IL 61822
Erich Loepke wrote:
A cheap way to get test patterns if you are handy with computers is to make a DVD with test patterns and then use a DVD player connected to the TV as a generator. I'm not sure how "calibrated" this is, but for things like crosshatch and linearity patterns it will work well. Even using a color bar pattern still resulted in decent color adjustment with normal video afterward. I have a couple of cheap players from Goodwill around here for this purpose. It's a cheap and workable alternative to getting a test pattern generator off Ebay and getting it to work. I still want to get an actual color bar generator sometime, however. There used to be a website that had a free download file that you could burn to a DVD, but it seems to be gone. I still have that file on my computer but didn't have success making another test DVD using it, so I decided to roll my own.



I can supply FREE jpeg files for all normal uses. You can burn them to a CD or use a USB stick
on anmy play that supports jpgs. I think I will post the more useful ones on the test equipment forum
at videokarma.org. These all work just fine.


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 Post subject: Re: Getting started on Admiral 19F1
PostPosted: Dec Wed 18, 2019 10:53 pm 
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Joined: Feb Wed 03, 2016 9:11 pm
Posts: 68
Location: Savannah, GA
Here it is with a signal applied.

Attachment:
IMG_1780.jpg
IMG_1780.jpg [ 416.68 KiB | Viewed 1357 times ]


Here is without

Attachment:
IMG_1783.jpg
IMG_1783.jpg [ 419.83 KiB | Viewed 1357 times ]


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 Post subject: Re: Getting started on Admiral 19F1
PostPosted: Dec Thu 19, 2019 3:18 am 
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Joined: May Thu 14, 2015 4:15 pm
Posts: 2342
Location: Dallas, TX
If yours is a run 8 it should have the vertical blanking circuit so pin 2 shouldn't really be ground. It may read zero on a meter but there should be a signal there.
The pin 10 anode voltage is derived from the boost voltage which is developed in the horizontal output section. "Boost voltage" is a higher voltage that B+. The problem source looks like it is in the horizontal section. Check to see that the horizontal frequency is about right. Check waveform W13 which is near the grid of the horizontal output tube.

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Tim
It's not the Destination, It's the Journey.


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 Post subject: Re: Getting started on Admiral 19F1
PostPosted: Dec Sun 22, 2019 7:18 pm 
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Joined: Mar Sun 01, 2009 10:27 pm
Posts: 5296
Location: Ann Arbor, MI
As mentioned above, the voltage on pin 10 of the CRT is from the boost voltage. That is generated by the same mechanism that generates the high voltage. The symptom of the picture disappearing when the brightness is advanced could be caused by the high voltage collapsing when the CRT tries to draw more current from the high voltage. With the reduced power in the horizontal output section, the 1B3 high voltage rectifier would have reduced filament voltage and could just be unable to supply even the reduced power available.

From the picture posted, it looks like the horizontal frequency is very close to the correct frequency. Close enough that adjusting the horizontal hold would bring it in, and close enough that that is not the problem. You could try adjusting the horizontal hold just to see if the picture you have will lock in.

A couple of thoughts:
In the vicinity of the horizontal output transformer (flyback) and the damper tube there is a cap that serves as the boost filter cap. That cap is often rated at 1000 volts rather then the more common 600 volts. Check that you did not replace a 1000 volt cap with a 600 volt cap. Also, although mica caps were once thought to never fail, mica caps with a lot of voltage on (such as in the horizontal circuits) are failing fairly frequently. So try replacing any mica caps in the horizontal circuits. Also check that no resistors have now changed value. And make sure that you did not forget to solder any connections.

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