#61
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There is no way i would use those surface mount caps unless you want to see a failure in a day or so. throw them in the garbage.
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#62
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Why exactly ? Just because they are surface mount ? They'll work just fine.
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#63
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Justradios dot com has 4 mfd@500 volts. I'm just leery of those type of caps. Keeping an eye on them would be good. If they do leak, be careful. If you are using a Weller soldering station, the goo eats the tips up in less than a day.
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#64
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Meanwhile, I pulled all the tubes for testing. Unfortunately, careful as I was, the cap broke off the 6JS6 and let the air in
The tube looked well used and may have been weak, but now I'll never know for sure. I have 1,000s of tubes NOS and pulls but had a heck of a time finding a replacement. As for the others, I check them with a TC-162 and found many had shorts or excessive grid leakage. Luckily, I had replacements for all on hand. While searching I came across this Servicemaster 3AT2 made in Korea. I think it's the first Korean tube I've come across. Don't plan on using it, just though it was interesting. Back to the 6JS6 saga. I finally dug up a used one that tested good and popped it in. Hmm. Nothing on the screen. Let it run a while and slowly the screen lit up dimly with a weird image. A while later, it got a little better. I hooked up by Seco meter and found it was drawing less than 100mA. Schematic calls for 225. Time to search for another 6JS6.... |
#65
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Just as I was about to give up, I found one mixed in with my octal tubes
It certainly draws more current, but no HV at first then it suddenly sprang to life and I got a nice, bright image back. At least until I turned it off and back on. No HV, drawing 200mA and starting to red plate! I popped it back in the tester and found it has a short. I was able to tap the side a few times and clear it out. Put it back in the set and it has been been working without trouble for a couple hours. Even so I'm not crazy about leaving it in the set so took a chance and bought a NOS tube on ebay for $14. I got lucky and it works great! The image now fills the screen, vertical linearity is pretty good and no more streaking. I do still need to cleanout the HV cage and fabricate a shield for the HV shunt regulator. Eventually, I'll pull the chassis and go over it too. Even though it's working pretty well, it's got issues. Like I sporadically loose vertical sync, and focus control is at one extreme, occasional arcing and dirty controls. |
Audiokarma |
#66
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One last thing for now, I stumbled across a NOS channel knob on eBay.
After a bit of a struggle, I got the old knob off. The clear plastic fine tuning was filthy and got a good cleaning. Here's how I've got the bulb sitting in it's holder. I'm not sure I've got it positioned quite right. Here's what I got after fighting with it a while. I really need to setup a mirror so I can see what's going on while I position the bulb. Even so, it's definitely better than before. |
#67
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One of my favorite Zenith channel knobs!!
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#68
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Nice. You do good work on your set's.
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#69
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Quote:
__________________
Just look at those channels whiz on by. - Fred Sanford |
#70
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Replacing the tubes definitely helped. There is a HV adjustment control. It could be we need to tweak that and our focus would be good mid range on the control.
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Audiokarma |
#71
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Has any more progress been made on this set? I'm interested to see how it turned out.
__________________
"If you wish to make an apple pie from scratch, you must first invent the universe." -Carl Sagan |
#72
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No, sorry I haven't had time for any projects the past few months. I've been too busy with work and fixing up my house.
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