April 18, 2023 at 2:12 am #24693
Looking for help or someone to repair a Stark 12-22 tube tester, close to or even in NL would be preferred. Must have great working knowledge of tube tester repair, already had one bad experience at a repair shop.April 18, 2023 at 5:00 pm #24696
As you know, I am in Ontario. And even here, I know I would be hard pressed to find a truly knowledgeable Tube Tester Technician. Of course, I myself do not know, if the last Tech who worked on your Tester, or as to what he knew or what may have messed up.
Most of what I am saying here, I have learned from restoring my Jackson 561 Tester. Also do you have a schematic for this Stark 12-22. While your Stark is more complicated than my 561, it should not be too hard to do it yourself. Just like a radio, replace all the caps, test all resistors, clean all the switches and pushbuttons, Potentioameters/Rheostats with Dioxit. Clean all tube sockets real good, and if you have another Tube Tester you can really trust, check the tubes used in your Stark Tester, including cleaning the pins. PS: When checking resistors, remove one end of the resistor to ensure nothing else in the circuit will influence the reading.
As line voltages change during the day as loads placed on the grid can change, I would use my tester on a reliable Variac to ensure that I am getting reliable Filament Voltages on the Filament Switch. This is important when seeking optimal working conditions for the tubes being tested. It will effect other necessary voltages also.
Also let the tester warm up of ten minutes or more. Also too, make certain the tubes in you unit are up to snuff. This also applies the the Meter itself. A faulty meter guarantees you have a Tube Tester which is not accurate.
However if the meter is just a little off, you will soon get to know its limitations, and will be able to compensate for its shortcomings.
Do you have a copy of the Operating Manual for this Tester. Also do you have a proper Schematic. These machines are not Rocket Science, in fact maybe easier than most radios you work on, so there is no reason why you should not be able to get this tester into reasonable working condition, barring a blown meter, of course.
Regards RalphApril 19, 2023 at 1:08 am #24699
Hi , Ralph , i do no have a good schematic. The bottom wafer was replaced from another switch from same tester, it has two white wires with red stripe on them, wondering if they got mixed up.April 19, 2023 at 6:42 am #24700
Man, you were up and at it early this AM.
I am assuming you are saying, there was wafer section on your Tube Tester that was not being used in the circuit. If so did he switch out the two wafers, or just re-route the wiring. The fact that both red and white wires were switched over, I dont think how they were connected would matter???
Can you send/post me a copy of the Schematic you have. Do you have any idea if the actual meter is functioning properly. Also I have some suggestions on setting yourself up to test Filament, Hi-tension voltages, as well as other voltages. This would prove that your Power Transformer is working properly. Aso some good, hi-defination pics of the chassis, both from the top and bottom would help. Explain a little more fully what the switching out of the wafer/switch involved. A close-up of the said wafer/switch would maybe shed some light on the subject. Don’t let the big picture (the bowl of spagetti) get you off track. It’s not as complicated as one may think.
We may be more successful if we get into the nuts and bolts of this, using email. As we progress we could then post our successes or failures here at CVRS, for others whou may be dealing with similar Tube tester problems. Also I would say, get to know yout particular piece of test equipment as to its weak points and learn how to compensate.
RalphApril 19, 2023 at 12:23 pm #24703
Hi Ralph, the tester is working in all other functions according to shop, he has a tester just like it and compared both.April 19, 2023 at 1:00 pm #24704
So Sterling, you say the Tester is working on “all other Functions”, but you do not say which function, it is, that is not working???? It sounds like there is not much wrong with it. Should be easy to zero in on and correct. You are already over half way there. Let me know which function it is that is not working??? I may need a copy of the Schematic! Also can you let us have close up pics of the wafers in question. If he just disconnected the two wires, and re-connected them to an open switch on another wafer, that set of contacts would have to be in the same position on the second wafer as it was on the first wafer?????
RalphApril 19, 2023 at 1:56 pm #24705
The shop said it can test tubes but shorts not working. The wafer came off a complete switch from another exact tester, the wires were still attached to replacement wafer so should have been able to exchange quite easy.April 19, 2023 at 2:07 pm #24706
PicsApril 19, 2023 at 3:52 pm #24708
Attachments:April 19, 2023 at 4:07 pm #24710
Hi Stirling, no pics came through. however, how do you know that the Short function is not working. Have you or the other Tech actually tried to test a known faulty/shorted tube. That is the only way you will know if it really is a problem ot not??? Maybe just maybe there is/was no shorts to find in the tubes you were testing??? I’m just looking for simple solutions. Ya gotta look at everything.
At first, the system of checking for shorts on this tester can be a little hard to understand and a little tricky, to say the least, for anyone who is not use to using this particular tester. See the section, under Shorts, Pages 8 and 10 in the Manual. Took me a while to figure out all they were saying.
RalphApril 19, 2023 at 4:13 pm #24711
The pic just came thru. Are the two red and white wires, the two that are on the lower /bottom of the wafer. His work seems to be not to bad, even acceptable. But having said that, what’s the story on the two green wires that are just hanging there, conncted to nothing. The same can be said for the gray wire, the mauve wire as well as the white wire near the top of the wafer???
Again, the secret behind all of this should be in the Schematic.
RalphApril 19, 2023 at 4:16 pm #24712
Yes that is the two wires. The tester shows short with no tube in place.April 19, 2023 at 4:28 pm #24714
OK, now we are talking. I would like to see the schematic for this thing. Something does seem to be wired wrong???
RalphApril 19, 2023 at 4:29 pm #24715
I cant find a schematic.April 19, 2023 at 4:29 pm #24716
But only on certain settings
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