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  #1  
Old 08-29-2008, 10:10 AM
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mattdavala mattdavala is offline
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Beltron results

Hi everybody!

I've tried my beltron 8080 at cleaning a 14QP4 with great results. BUT


I had to try restoring a 21EP4 but the Beltron wasn't operating as per the instructions. On the restoring function, there was no current shown on the meter, and none of the restoring lights lit up. I only tried it once. The instructions said that the current meter should go up around 80 and then I should press the interrupt function.

The tube is improved, but it could have been from the cleaning function.

The lights were just replaced. Any ideas?

Thanks
Matt Davala
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Old 08-29-2008, 10:30 AM
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Nevermind!!

I checked one of the new restoring lamps and it was open.

Alrighty!

Matt D
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  #3  
Old 08-31-2008, 04:01 PM
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Ok!

Help! My Beltron doesn't work in restore position! The restoring lights have continuinty. There is no current shown on the restoing meter, and the restoring lamps don't light up.

I don't have a schematic of how this thing works. Would this be a capacitor issue? I thought if a cap was shorted that the fuse would have blown.

Quite annoying!

Thanks for your help. Its a 8080 Beltron again.

Matt Davala
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  #4  
Old 08-31-2008, 09:23 PM
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kbmuri kbmuri is offline
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To quote Charlie Brown, "Good grief".

OK, I took my 8080 apart and had a look.



The horizontal yellow metallic cap just above the power transformer is a 150mfd@150v. The vertical orange cardboard cap is something at 350V. Can't read it. Those should be replaced, but I don't have them on hand. I tested them in circuit and they're not currently leaking and they're holding a charge, so for the moment they're fine. I put it back together.



It's the one on the right. On left is my 2972. Only external visible difference is the extra voltage switch on the bottom-left of the control panel.

I went ahead and sacrificed the AMP connector and built a universal adaptor.



The black clips are filament, green is K (cathode), and yellow is G1 (1st grid). I checked a good 10BP4 and got identical results as my 2972. Then I checked a NOS 5FP14 radar tube that I've never tested before because it's an octal base (2972 doesn't support it). It tested .98 mA and 15 seconds life which is normal for NOS, so I guess the test function works.

I grabbed a 7JP4 from the junk pile. Never tested it of course (funky huge socket). It came in an eBay purchase that was mishandled by UPS. The deflection plates in it are broken loose from where they belong and just rattling around in there. No real hope of fixing that. I got a 7JP4 pinout diagram from the web and clipped on the clips appropriately and checked it out. For about 3 minutes there was no emission, then a little, and after about 5 minutes I had a 0.1mA reading and no life test. Pretty dead. I went to step 2, cleaning. Took several minutes for the cleaning light to glow dim, then a minute or so to brighten up. 20 seconds at bright, per instructions. Went back to step 1 and had a 0.8mA emission and a pretty poor but passable life test of 1-2 seconds. At this point normally you'd say "good enough", but WTF, the crt is toast anyway. I went to restoring mode. On bringing up the filament voltage I got a couple of bright flashes on the restoring lamps, like yoda described on another post. I'd never seen that before with my 2972 but maybe just coincidence. Anyway after the flashes, a minute later the lights glowed very dim and then slowly rose to bright over 10-15 seconds (normal operation). I cut the current twice and let it cool. Now it tests 0.95 emission and about 5 seconds on the life test. It would probably be very passable if it still deflected correctly. As it is, only Scotty can fix it, someday..?

So, long story short, I think my 8080A is functional. I'd be happy to take readings here and there if you want.

First off, the restoring lamps are in parallel so even before you repleced the open one you should have gotten a meter reading. At some point before 85 mA's you would have blown the other bulb though. Both bulbs have to share the .85 mA load. It's possible both bulbs were open, maybe the good one wasn't screwed in all the way? Even if, once you put the replacement bulb in, you should have had a current reading eventually.

If your test and cleaning functions work, the power transformer is ok. You should test each meter for continuity. Might be hard to do that in-circuit or might not. I could check that for you on mine. I'm guessing your restoring-current meter might be open..? That would be a tragedy. Parts are hard to come by except when an entire restorer shows up on that ePay place. A toasted meter would suck. But that's my guess from here. I can do some more digging tomorrow (Labor day holiday!).
Attached Images
File Type: jpg Truly-Universal-Beltron-8080-Adaptor.jpg (88.2 KB, 150 views)
File Type: jpg Beltron-8080-underside.jpg (115.6 KB, 153 views)
File Type: jpg Pair-of-Beltron-CRT-Restorers.jpg (75.2 KB, 149 views)
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Last edited by kbmuri; 08-31-2008 at 10:08 PM. Reason: said "cleaning" a couple of places, meant "restoring"
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  #5  
Old 09-01-2008, 12:42 AM
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Quote:
Originally Posted by kbmuri View Post



The black clips are filament, green is K (cathode), and yellow is G1 (1st grid).
Usually, green is for G1, yellow for cathodes, blue for the plate, orange I think for screen, black for ground, red for B+, brown for heaters. I might get confused with your setup, if I ever borrowed it...
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Old 09-01-2008, 10:10 AM
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Nobody sells brown alligator clip insulators, so black and black it is (AC isn't polarized). I thought about green for grid, just as a mnemonic device, but in the end I just matched clip-insulator colors to the wires as-is, just for looks. We can both yell at Beltron for making K the green wire and G1 the yellow wire (and one of the filament wires orange) in the original adaptor cable.

I looped a red, a blue, and a black wire back around to the cable and electrical-taped them down. I could put clips on them later, for color CRTs, but for now that would just add to the confusion.
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Old 09-01-2008, 10:52 AM
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I popped open the 8080 again. I've had the same old boxy Micronta 20,000-ohm Multitester since 1978, back when Radio Shack used to be a real electronics store. I was able to probe all 5 meters in-circuit. The leftmost power meter, with the Ohmmeter set at Rx1, black probe tip placed on the 8080's power meter post marked "+", I was able to deflect the 8080's meter a few degrees (the Micronta Ohmmeter deflected all the way to 0 Ohms). The Red, Green, blue meters get pegged pretty hard at the Rx1 setting, but at the Rx1K setting the meters deflect softly a few degrees. Again, always black probe on the "+" labeled meter post. The "Restoring Current" meter gets pegged at Rx1 and doesn't noticeably deflect at Rx1K, but on the rX10 setting, again, a nice soft deflection.

Your mileage may vary, of course, with a different VOM. Pretty sure Rat shack still sells a version of my meter, ergonomically restyled and more hip-hop of course, but you gotta ask for it, they push a yellow digital LCD readout one that I don't care for. But I'm old school. Analog meters are best.

In every case I got 0 Ohms on my Rat Shack meter. The 0-Ohm reading may be thru the meters or thru other circuits though, as I kept the meters in circuit. So what matters is getting the 5 8080 meters to deflect. Tells you they aren't smoked. I see that each meter has screw-down terminals so it's real easy to take them out of circuit if you want to thoroughly inspect them, but what I outlined above should suffice. I didn't want to disturb mine by taking them out of circuit. You shouldn't have to either.

Because the Restoring function uses the third Octal socket, you might want to inspect the wiring around the 3rd socket for anything loose. Might be as simple as a corroded solder joint there.
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  #8  
Old 09-01-2008, 05:35 PM
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Matt,
Your Red,Green,and Red selector switch must be in the GREEN POSITION for the restore function to work on a B&W picture tubes. Look at the two electrolytic caps and if they are not leaking don't change them. All i have replaced were leaking. On some tubes i have had to increase the filament voltage to max to get them to take. Haven't lost a filament yet on one. Hope this helps. PM sent.

Later,
Don
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  #9  
Old 11-07-2008, 09:10 PM
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Matt never updated this thread, but in conversing with him I learned that the main electrolytic capacitor (the orange cardboard one) was open. He fixed it and all went well afterwards.

I just received a "new" CRT this evening in the mail. It's the Farnsworth roundie shown here: http://www.earlytelevision.org/class...parts_for_sale

Using the 8080 and my alligator clips, as usual, it was dead as a doornail. No emission even after a slow "variac" up and then a long 20 minute burn. I tried a "clean" operation and got no lights. Had to "restore' it. Then the clean operation worked, then back to test. 85 mA and 6-7 seconds life. It would work fine if I had a TV set to put it in.

Anyway, another Beltron success story.
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  #10  
Old 03-24-2018, 06:58 PM
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Beltron 8080-a normal voltage issue

I’ve always heard great things about the 8080-A and got one.

However I’m trying to figure out what seems to be a big problem.

In the normal position, the heater voltage is reading 15 volts. I can make adjustments in the 12v color and 12v black and white setting.

I measured the actual voltage at the meter and it shows 14.8 volts so the units meter is working correctly. I thought perhaps the 160ohm resister was bad but it’s within 5% of its rating.

The caps are not leaking but I’ve not checked them yet.

Any thoughts as to what might be causing the voltage to be so high?

Thanks all.
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Old 03-24-2018, 07:20 PM
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Hows your wall voltage?
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Old 03-24-2018, 07:31 PM
Crist Rigott Crist Rigott is offline
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I have a 2972-E and the filament voltage meter pegs when plugged in and the test cable is not connected to a CRT. I'm pretty sure this is normal. Once a CRT is plugged in, the filament voltage control works. I always turn down the control before I plug in a CRT.
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Old 03-24-2018, 09:07 PM
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Originally Posted by RCAkid View Post
Any thoughts as to what might be causing the voltage to be so high?
Is it that high under load?

.
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  #14  
Old 03-24-2018, 09:39 PM
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It’s not under load. Being such a vintage item I just didn’t want to take any chances.
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Old 03-24-2018, 09:39 PM
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Wall voltage is 121
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