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Tube tester: Sencore MU-150

Thank you Brice. I appreciate yor help again. I will give another tube a go, I have many of these 12AX7 tubes from scrapping organs for the amplifiers, speakers and palladium wire from Hammond organs.
 
Thank you Brice.

I found a 12AX7 tube that was well balanced when tested on my Hickok 600A and installed it. It stall makes a meter swing on power up to a greater degree, but returns to zero more rapidly than with the original tube.

I've concluded that the metervswing on start up is normal.

I can't say that I fully understand the tester circuits, I worked mostly with TTL logic and rack mount mini computers with magnetic core memory. I can follow lines on a schematic and know what the schematic symbols correspond to though. I can still work my Fluke multimeter and Techtronics 475 scope.

I'm 70 yo and suffering from brain rot. I'm hoping making these types of repairs will stave off dementia.

I truly appreciate the help you provide Brice.
 
Hi Vlad.

You're welcome.

You did well. The MU150 is a fantastic tester, but not that easy to restore and calibrate despite my effort to document it all.

Just to make sure, the tube in this tester is not a 12AX7 but a 12AU7. And yes a slight move at startup is normal, as well as a zero adjustment after the tester has warmed up.
It's all good fun :)

Brice.
 
Thanks for spotting my brain rot Brice. I did install a 12AX7 tube in the tester. I did put a proper 12AU7 tube in the tester today though. It is not as if I'm in short supply of 12AU7s. I scrapped a Conn brand organ last week and harvested 43 of the 12AU7s from the organ doner.

Eric aka Vlad (a monkey with a soldering iron [and the burns to prove it]).
 
Again Brice, thank you.

I have not done so yet but I also thought calibration verification would be appropriate.

I do find the Sencore MU-150 is easier to calibrate than the Hickok 600A that I have. Fewer steps with the Sencore than the Hickok but I like using the Hickok more than the Sencore when it comes to testing.

I did find that when setting the low end F signal I had to use my scope. My Fluke model 75 DVM was not sensitive enough to measure the signal. I may give it a try using a Simpson meter that I have. Perhaps it can read in thr 15 milivolt range that is required.

Eric aka Vlad (a monkey with a soldering iron[and the burns t prove it])
 
Again Brice, thank you.

I have not done so yet but I also thought calibration verification would be appropriate.

I do find the Sencore MU-150 is easier to calibrate than the Hickok 600A that I have. Fewer steps with the Sencore than the Hickok but I like using the Hickok more than the Sencore when it comes to testing.

I did find that when setting the low end F signal I had to use my scope. My Fluke model 75 DVM was not sensitive enough to measure the signal. I may give it a try using a Simpson meter that I have. Perhaps it can read
 
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