View Full Version : Zenith A4007E (Chassis 19A20Q) Issues.


OS X
08-13-2016, 02:40 PM
I'm on to my next project now, this set will be my daily watcher once it's finished!. It worked ok on original caps but after running for around 5 minutes the vertical would start to shrink so I decided to do a full recap including electrolytic's, I finished up the recap last night plugged the set in and got a raster but a horizontally shrunken one, so I used my high voltage probe to measure the high voltage and it was only running around 10KV so I switched out the horizontal output tube for a different one even though it tested okay on the tester and that brought it up to 16KV, also had some other issues that we're related to bad solder connections but fixed that, one thing I learned about this set is it's very picky on what tubes it likes even if they test good. It's a high hours set and the flyback is in pretty bad shape but I used Corona dope and it seems to be ok. It produces a solid picture just with decreased horizontal width, is there a pot on the chassis to adjust the HV? Although I'm sure that would only be a temporary fix as there's more than likely an underlying problem why the HV is low to start with, and that's what I'm trying to figure out. Would you guys have any ideas? unfortunately I do not have the Sam's for this set and my troubleshooting skills are limited as i'm still learning. Thanks for your help in advance :)

tom.j.fla
08-13-2016, 02:58 PM
There should be a metal band(sleeve) on the neck of the CRT . The more it is inside the yoke the smaller the raster(picture). Pull the sleeve out of the yoke to make the picture wider. Remember to loosen the yoke clamp first. All the best, Tom

OS X
08-13-2016, 03:01 PM
Pictures....

OS X
08-13-2016, 03:01 PM
There should be a metal band(sleeve) on the neck of the CRT . The more it is inside the yoke the smaller the raster(picture). Pull the sleeve out of the yoke to make the picture wider. Remember to loosen the yoke clamp first. All the best, Tom

I know exactly what you're talking about I'll give that a try thanks :)

Electronic M
08-13-2016, 11:56 PM
No monochrome sets that I know of ever had HV adjustment controls....That was only for color sets.

dieseljeep
08-15-2016, 11:21 AM
I'm on to my next project now, this set will be my daily watcher once it's finished!. It worked ok on original caps but after running for around 5 minutes the vertical would start to shrink so I decided to do a full recap including electrolytic's, I finished up the recap last night plugged the set in and got a raster but a horizontally shrunken one, so I used my high voltage probe to measure the high voltage and it was only running around 10KV so I switched out the horizontal output tube for a different one even though it tested okay on the tester and that brought it up to 16KV, also had some other issues that we're related to bad solder connections but fixed that, one thing I learned about this set is it's very picky on what tubes it likes even if they test good. It's a high hours set and the flyback is in pretty bad shape but I used Corona dope and it seems to be ok. It produces a solid picture just with decreased horizontal width, is there a pot on the chassis to adjust the HV? Although I'm sure that would only be a temporary fix as there's more than likely an underlying problem why the HV is low to start with, and that's what I'm trying to figure out. Would you guys have any ideas? unfortunately I do not have the Sam's for this set and my troubleshooting skills are limited as i'm still learning. Thanks for your help in advance :)
According to the code dates on the original tubes, that chassis is the first one Zenith built after they had built the two or three years of the hard-to -work-on upright chassis. That model sure was an improvement. :thmbsp:

Kamakiri
08-15-2016, 02:29 PM
There should be a metal band(sleeve) on the neck of the CRT . The more it is inside the yoke the smaller the raster(picture). Pull the sleeve out of the yoke to make the picture wider. Remember to loosen the yoke clamp first. All the best, Tom

He fixed it. That did it!

OS X
08-16-2016, 01:58 PM
There should be a metal band(sleeve) on the neck of the CRT . The more it is inside the yoke the smaller the raster(picture). Pull the sleeve out of the yoke to make the picture wider. Remember to loosen the yoke clamp first. All the best, Tom

Thanks that worked! Now got around 21KV and a very good picture :) spent about an hour getting everything just right, only thing it needs now is a new tube socket for the 6BQ5 then I'll call this one done, also still have to figure out the speaker situation but that's the easy part now.