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 Post subject: SECO 107B Tube Tester
PostPosted: Sep Tue 07, 2021 9:26 pm 
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Joined: Sep Tue 07, 2021 9:20 pm
Posts: 3
I just bought a SECO 107B tube tester. I did have a bad panel meter which I changed for a good one. When I try to calibrate it the needle goes all the way to the right and I cannot adjust the meter back to the 100 calibration mark. Do anyone have a suggestion on what is wrong? Thanks


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 Post subject: Re: SECO 107B Tube Tester
PostPosted: Sep Tue 07, 2021 11:40 pm 
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Joined: Jan Tue 10, 2012 8:39 am
Posts: 2805
Perhaps the replacement meter has too much sensitivity.


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 Post subject: Re: SECO 107B Tube Tester
PostPosted: Sep Tue 07, 2021 11:50 pm 
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Joined: Nov Wed 30, 2016 7:35 pm
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Location: Sunbury, Ohio 43074
Where did you get the new meter? Can you post up a schematic of the tester? No one keeps these things in their head.....

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 Post subject: Re: SECO 107B Tube Tester
PostPosted: Sep Wed 08, 2021 4:48 pm 
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Joined: Oct Thu 04, 2018 2:11 pm
Posts: 815
Location: Suburban Chicago
I don't have a 107B schematic, here is the 107 schematic as redrawn by another owner. He does indicate some meter parameters that were measured on his unit(s) and hopefully they will be helpful. These testers have a traditional switched test side which can test any tube if the test parameters are available and a hard wired side for some specific tubes. They also have a magic eye tube test for shorts and other tube faults.

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Seco107_Redraw.jpg
Seco107_Redraw.jpg [ 584.03 KiB | Viewed 411 times ]


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 Post subject: Re: SECO 107B Tube Tester
PostPosted: Sep Mon 13, 2021 12:24 am 
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Joined: Sep Tue 07, 2021 9:20 pm
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Thank you all for posting. Sorry it's taken so long to reply to what all of you have posted. I am not an electronics guy and have had no training in electronics. Having said that I find it interesting and would like to learn how to work on electronic devices. So please keep it simple (kindergarten/ pre-schools level). So, here is what I know about the tube tester. I bought the replacement panel meter off eBay and the seller posted that the meter was tested and is good. I was able to get schematics for the meter and have attached them to this posting. By coincidence an elderly couple were doing their nightly walk by my house one evening, we struck up a conversation and he is a retired electronics instructor for a local technical college. He said something about filters drying out and bleeding AC?? I don't know what that means so I'm posting it. I figured someone could breakout some color crayons and explain it to me. Hopefully there is a way to test for it and fix it. Anyway that's all I know. Thanks again for all the postings.


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 Post subject: Re: SECO 107B Tube Tester
PostPosted: Sep Wed 15, 2021 2:24 pm 
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Joined: Oct Thu 04, 2018 2:11 pm
Posts: 815
Location: Suburban Chicago
I am not sure how to help you. You are in over your head here and no shame in that, it is exactly where beginners are expected to be! In person help would be a lot more valuable for you right now than remote help via the internet. I wonder if your neighbor would be interested in giving you a hand? Or, is is possible to take a simple electronics course at a local community college or adult education program at a high school? Without that much of what I say below will be Greek to you, I am afraid.

Maybe someone else here can point you to a thread for newbies that will help you understand the things I say below.

I have a 107 and both you and I have posted a schematic for the 107. But yours is a 107B so already we are in the dark a bit since we do not know the differences between them. In the 107 there are 8 uF and 10 uF electrolytic capacitors that need to be replaced before you can expect proper operation. They contain a water based electrolyte and while they are sealed the seals are not perfect and a lot of the water has evaporated out over the decades since they were new. This is what you neighbor meant by filters drying out.

There are also four (by my count) other capacitors 0.005, 0.01, 0.022, and 0.1 uF. They may well be paper/wax capaictors which will have become unusable over the years due to internal corrosion and would need to be replaced. But if they are ceramic or mica caps they are probably good and can be left alone.

There are three "SELECTRON 8Y1 2F" selenium rectifiers. They may be fine, they may have gone bad. One of the three in my 107 had gone bad, the one over by the 8 uF cap and it had to be replaced with a modern silicon diode.

And then there is your meter. The new meter may or may not be suitable for this tester. Is it a meter out of another 107B? If so then it should work and the issue probably lies in one of the parts I mention above. If not then it may take some work to make it function properly in this tester.


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 Post subject: Re: SECO 107B Tube Tester
PostPosted: Sep Fri 17, 2021 6:19 pm 
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Joined: Sep Tue 07, 2021 9:20 pm
Posts: 3
I really appreciate your response. You're correct in that I do not understand your explanation but at least I have some something I can show an electronics guy. I've looked at the local tech college and they do offer basic electronics but nothing having to do with Vacuum tube type equipment. While searching the web I did notice that there are places that repair tube based amplifiers. Could a shop like that work on my tester?


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 Post subject: Re: SECO 107B Tube Tester
PostPosted: Sep Sat 18, 2021 10:50 pm 
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Joined: Jun Tue 17, 2008 4:11 pm
Posts: 224
Location: Mt. Rest, SC, USA
A good place for a beginner to start is to buy a copy of Igor Popovich's How to Use, Calibrate, Repair and Upgrade Vacuum Tube Testers and Joseph Carr's Old Time Radios. Having a neighbor who used to teach electronics is another wonderful resource.

Most of the restoration process consists of replacing paper and electrolytic capacitors with new types, as these are so unreliable they can be considered bad, and any resistors that have drifted outside their tolerance. The selenium rectifiers would likely be bad and should be replaced with silicon types.

The 107B is different from the 107. It is missing the eye tube, uses a circuit breaker instead of a fuse, is modified to allow tubes like compactrons to be tested, and has a different gas test. The only schematic I found for it is https://bama.edebris.com/download/seco/107/seco-107b-flipchart.pdf and it is hard to read.

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