Tweet
Im trying to calibrate my Sencore tc162. I have replaced and checked all components, so they are all matching schematics values. I still cant get the grid emmissions test part to be in the place where its supposed to be. Ther are 2 trimpots which are the correct value and all other parts are correct value. I can 0 out the shorts section but when I switch over to the grid test it is out of range and the trimpot moves the pin a little but does not bring it to the point the manual says it should be. Anybody have experience with calibrating this tester or ones similar?
-
-
I'm not personally familiar with the exact unit but is sounds like you are tweaking ad hoc. Do you have the maintenance manual and are you following the specified calibration procedure?
Some of the old cal procedures require that a 1,000 Ohms/Volt meter be used. If that's the case and you don't have one then you would need to simulate one. Sometimes a cal procedure requires a specific sequence of adjustments, an iteration of two adjustments or even test selected specific component values. I'm not saying these things are related to your problem. It could be so many things. I just wanted to contribute some food for thought. -
I also seem to remember that you should use an analog meter.
Digital meters won't cut it.Comment
-
Yes I have the manual and am following the calibration procedures. There is a module which you have to make from an octal base which I have made and all seems to be accurate on it. Just cant get it in the right range and cant figure out why, all the instructions about it seem to suggest if the individual values are right it should calibrate easily.Comment
-
Are you using an analog meter?Comment
-
Val,
My comments, in post #2, about using a 1,000 Ohm per Volt meter were based on research I did regarding my TV-7D/U Tube Tester. This may or may not apply in your case. Attached is a copy of some tube tester alignment hints that I saved which includes the information. The service manual for my tube tester, printed in 1960, does not directly address the characteristics of the voltmeter to be used for calibration. However, it does specify the model of the meter which should be used. The point is that they were using a VOM with a relatively low input impedance. If someone were to have tried to use a VTVM, which was another type of analog meter available back then, they would not been able to do the proper calibration on the TV-7D/U because the VTVM has a much higher input impedance than the older, simpler volt meters. The same situation applies to using a modern DVM. The attached file, TV-7 Tube Tester Alignment Hints.pdf, explains the why and what to do about it.
TomTV-7 Tube Tester Alignment Hints.pdfComment
Comment