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  #31  
Old Yesterday, 09:40 PM
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So, I was messing around with the TV and letting it run for a little bit. Lost the vertical hold from a few resistors soaring in value. Fixed that, but still can't get a crisp picture from this set. I can adjust the focus magnet to get a pretty good image, but it sorta stops at a point. Any ideas?

Also, anyone know where I can obtain test picture tube? Brushing up against the CRT isn't my definition of fun. I haven't seen any round versions on the Bay recently.
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  #32  
Old Yesterday, 10:20 PM
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Do you have the brightness most of the way up? If so it could be that the CRT is near the end of it's useful life, which at that point the electron gun looses it's ability to focus well. It's also dependent on HV, so it could be that your HV is still on the low side. Try dimming the room lights and see if bringing the brightness down helps sharpen the picture any.

Another thought is if the ion trap is on the neck reversed end for end it could be limiting your overall brightness.

Considering the amount of ambient lighting in your shop I'd suggest your CRT is doing it's level best at producing a decent picture. These early tubes were never intended to be watched in a well lit room. The screens simply can't produce a high enough level of contrast with the brightness turned up high. Just remember that the CRT face can only go as dark as the ambient light reflecting off it's face. In other words the CRT can't make it self go any darker, it can only lighten up. That's ultimately what limits your contrast. Hope that makes sense.


Last edited by Kevin Kuehn; Yesterday at 10:42 PM.
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  #33  
Old Yesterday, 10:52 PM
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One of the 8" rectangular test tubes with the same base (8AXP4 IIRC) will work on the early sets, but the screen will not be filled due to the difference in deflection angle.
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  #34  
Old Yesterday, 11:59 PM
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Quote:
Originally Posted by Kevin Kuehn View Post
Do you have the brightness most of the way up? If so it could be that the CRT is near the end of it's useful life, which at that point the electron gun looses it's ability to focus well. It's also dependent on HV, so it could be that your HV is still on the low side. Try dimming the room lights and see if bringing the brightness down helps sharpen the picture any.

Another thought is if the ion trap is on the neck reversed end for end it could be limiting your overall brightness.

Considering the amount of ambient lighting in your shop I'd suggest your CRT is doing it's level best at producing a decent picture. These early tubes were never intended to be watched in a well lit room. The screens simply can't produce a high enough level of contrast with the brightness turned up high. Just remember that the CRT face can only go as dark as the ambient light reflecting off it's face. In other words the CRT can't make it self go any darker, it can only lighten up. That's ultimately what limits your contrast. Hope that makes sense.

When I do most of the adjustments, I keep the lights down, Iíve found that the fluorescent lights are way too bright, but that a light on in the back isnít too bad. Brightness isn't bad, I have it up at about 3/4 brightness. Any more and the image washes out. The HV is still running lower than spec. (still 7.5kv) I replaced a bunch of resistors in the both the horizontal and vertical sections to fix a few issues. Iím gonna try injecting a composite signal tomorrow to see where that gets it. Hopefully itíll make it easier to make adjustments that way. Also, is there an easy way to tell which way the ion trap goes? I donít think the one on the unit is stock, and it doesnít have an indicator.

Quote:
Originally Posted by Electronic M View Post
One of the 8" rectangular test tubes with the same base (8AXP4 IIRC) will work on the early sets, but the screen will not be filled due to the difference in deflection angle.
Ok, great to know. Murphyís law, thereís none listed right now. Iíll keep a look out
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  #35  
Old Today, 12:05 AM
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Quote:
Originally Posted by Zsuttle View Post
I can adjust the focus magnet to get a pretty good image, but it sorta stops at a point. Any ideas?
.
When you say adjust the focus magnet are you adjusting the focus magnet itself or the focus potentiometer?
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  #36  
Old Today, 06:41 AM
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Quote:
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When you say adjust the focus magnet are you adjusting the focus magnet itself or the focus potentiometer?
Focus magnet, to my knowledge the H22 series only has mechanical focus.
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  #37  
Old Today, 10:29 AM
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Two things that may be worth doing towards the end of fixing the low HV: 1.) If you haven't done this yet and have several good 1B3s try swapping different ones in (tube testers while good at IDing dead HV rects are a poor indicator of how good they will do in a set). 2.) If a tube rect does not help try an SS HV rect...They made SS plug-in R-3A3s that will work in place of a 1B3, or if that is hard to get 5KV (or higher) PIV rated diodes are inexpensive online I'd grab 3-4 5KV diodes, string them in series and install them in place of the tube...Elimination of the HV rect tube filament load from the fly by switching to SS rect may bring the HV to spec.
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  #38  
Old Today, 12:16 PM
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Quote:
Originally Posted by Electronic M View Post
Elimination of the HV rect tube filament load from the fly by switching to SS rect may bring the HV to spec.
And don't forget there was some discrepancy between Riders and SAM's as to what the HV rectifiers series filament dropping resistor was suppose to be in this set. An ohm or two can make a big difference when it comes to a low voltage heater.
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