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Precise 111m tube tester restoration - Printable Version

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RE: Precise 111m tube tester restoration - klondike98 - 07-24-2016

very nice troubleshooting! Great to be able to reason out the problem. I'm more of a trial and error experimentalist Icon_lol

RE: Precise 111m tube tester restoration - TV MAN - 08-13-2016

Thanks Bob! This has been a challenge. A little different than a radio, but hopefully this will play a hand in the restoration of lots of radios, TVs and other vintage electronic gear. I got to studying on the jumpy meter. It seems this meter is very sensitive, and likes to act like a windshield wiper when it starts to measure, bouncing back and forth several times before settling. It also seems a little unstable during a test. Bugs me. So, I set up a Simpson meter beside it and watched things. It looks like it is tracking the line voltage. Maybe even amplifying it. Someone from ARF mentioned his was the same way, so I take it this is the personality of this tester. I have been through it, checking for bad solder connections and dirty switch contacts. I also noticed my old 111 and Jackson did about the same thing.

 So, I did some experimenting and came up with this: I found that a large value, low voltage electrolytic capacitor put parallel to the meter (across the existing 100mf cap) made a world of difference in the behavior. I found that a 1000mf on up made things behave a lot better. I had the best results using a 4700mf, 10v cap. The best place I found to connect this was across the center lugs of the meter reverse switch.
   
It seems to be working really well.
I have calibrated it, and need to move on to the cabinet. I am still looking for any tube data updates.

RE: Precise 111m tube tester restoration - TV MAN - 08-20-2016

I have the cabinet finished, things put back together and have tested several tubes. It seems fairly accurate for the most part, no tubes unusually low or high, other than a 6BQ5 tube, and I think the settings or something must be wrong in the chart, since even new ones test about half the minimum. The old 111 reads the same. Other audio output tubes test ok. Other than that, it works well. So, unless I need to recalibrate because of an error. What kind of meter to use is still a bit of a mystery to me, I used a Simpson 260, and a Fluke where it called for a VTVM.

 So, I pronounce it finished. Icon_wink
   


A few notes:

I have the complete construction manual.
Have 'improved' the schematic and parts layout by adding the part location numbers (R1, C2, etc.)
If anyone needs a copy, PM me.

Added 4700 mf cap across the meter - flat tamed it down and helps eliminate slamming the meter.

Found the primary of the power transformer reversed causing a no meter reading on Em test on anything using the D" (50V) setting on screen voltage. Don't know if this is a factory defect in the power transformer or an error on the schematic and build sheet.

Be very careful when removing or inserting into case. The test switch is exposed and can be broken. I recommend putting the face of the tester down, then gently and carefully remove or install case.

RE: Precise 111m tube tester restoration - TA Forbes - 10-07-2016

An outstanding job on a fine instrument. You will be pleased with it's performance!

RE: Precise 111m tube tester restoration - TV MAN - 02-26-2021

UPDATE:

I realized that I had found and made notes on a couple errors on tube settings and forgot to update my thread. Hope this helps someone.

50L6 settings are wrong. Use the 25L6 setting and 50v heater. This is on most charts.

6BQ5 settings are wrong, use 8BQ5 settings with 6v heater. This is not on all of the Precise tube charts, so here are those settings: