Heathkit TT 1 Rebuild and Alignment
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- čas přidán 29. 08. 2024
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In this video we take a look at another tube tester for the lab. I needed one and 3 showed up It is the way some things work. This time it is a Heathkit TT-1 with the A adaptors. This will finish off the tube testers for a while as this is all that is in the line for repair at the moment. The Heathkit I think will become one of my main tube testers as it has a calibration routine and I suspect will be the most accurate of the 3 that I have.
** Repair exposes the Tech to mains electric and should only be done by trained personnel. Errors can be fatal. **
Thanks for the nice video... My TT-1 arrives today, January 29th, 2024.. It does power on and you can set the meter for the line test. Other then that it is in unknown condition.. I have other tube checkers to test the 2 tubes.
I have a good selection of capacitors at my disposal. What I found as for the AC capacitors is you can get decent AC capacitors off, of all places, Amazon. These are Capacitors that are used inside Celling Fans, starter capacitors. You get 3 for around $10.00 at 3 and 7 UF values at 250 volts. I have used these in several pieces of vintage tube operated test equipment...
My Weston 978 same as the 981, but the 978 was built for the Aeronautical folks, has a 1Khz oscillator built in, the TT-1 has a 5 Khz oscillator built in and comparing schematics, Heathkit made some improvements to the overall circuit. Also the 978 has a ton more documentation available as the military contract requires them to create this, were as the later and similar 981 does not have very much detailed documentation available.
All my other 5 tube checkers have been rebuilt and calibrated. BTW, I just ordered a 6V6 Calibration tube as that seems like a good match for the TT-1 and many of my other checkers... I wanted to share this with someone who might come watch your video for several reasons...
Again thanks for the nice video!!! Robert WA6PHN
Thanks for the video. I have one of these from an estate sale. I sold some stuff but kept this because it is so beautiful! I had planned to use it at some point, but now I will probably at least recap it first.
73 Paul AA1SU
Thanks for the thorough vid. The bathtub cap in my unit is toast.
The one thing that I don't like about the TT is the control knobs for Bias and Meter. Specifically, the arrow indicator is too far from the number scale. I like being as precise as possible and you really need to trust your eyesight to get them aligned perfectly. Being a bit nit-picky but comparing with the Hickok, they could have done better in this regard.
Enjoyed the video. I have three TT-1's and just started rebuilding the first one. I replaced all the caps except the bathtub cap and also replaced
all the diodes.
the line test seems to work fine but when I start the calibrate routine nothing seems to happen. When I move to bias or signal or meter I get no meter deflection at all regardless of adjusting CD,CF or CG.. What should I be looking For as the problem.
Thanks
there are actually 5 Doides not 4. The 5th one is in the Grid switch
Hello, thank you for your video, it has been a great help in rebuilding mine. When I got this one it did not work, the meter needle hit the end when I tried to test a tube, after many hours of work and practically replacing the capcitors and some resistors It worked, but it didn't last long, when I tried a 6au6 and it got red plated and when I pressed the GM test button again the needle hit the end, then it stopped working, and I'm lost, I've already replaced almost everything I found defective, any help from you or someone who knows what may be happening would be of great help.
It makes the tubes intense red in tubes that are tested with 300ma,450ma and 600ma.
It worked again, the 3a4 tube was damaged, something caused it to break since it was a perfectly good tube, this is related to the parameter 300 ma, 450 and 600 ma, some help would be very helpful
Hi thanks for TT1 tube tester review I have the same one and am going to rebuild it, when I do test a tube on some tubes the needle drifts prior to gm test, what would you recommend I check to resolve this issue. Thanks again for this video it is so well done. Joe B
Thanks I am glad it helped. The diodes or the caps are the things that first come to mind. Seems the TT-1 diodes have a reputation for leakage as they age. The bathtub cap is of the age where PCB oil is suspected so opening the metal bathtub capacitor is not advised.
Just out of interest it would have been nice to see how the diodes you took out behaved on the curve tracer ! great work...cheers.
I don't believe you put the correct capacitors to replace the can capacitor. This is important to get the right current for the series current tubes. You need to add 3.6 uf and 7.1 uf +/- 3% capacitors.
You need a tube tester tester :D
I really could use one I was looking for 1 maybe 2. I did not expect 5 -7 :D
Did the "bad" 6L6 get hot at that final test where it showed good? Nice unit, my IT-21 is envious of its older brother!
After the full rebuild the 6L6 behaved even the “bad” one. I suspect there was something out of balance with the biasing as the unit was about ½ to ¾ restored. I am looking for an IT-11 or IT-21 for some fast testing when I don’t need GM There is WAY more documentation out there for those units as well as tube charts that are still being updated even today!
adjust the line voltage everytime after putting different tubes ? thx
Yes this is due to the tube under test variations in filament current draw and transformer loading. The voltage drop of the transformer and rectifier are very current dependent. At 12AX7 will load the transformer quite differently than a 6L6.
@@ZenwizardStudios thx