Mr. Carlson's Dual Display Capacitor Tester- fixed forecast problem.

I have that project to build, and I really have a need for it, so I will follow to see if you get help.

Hi, regarding the issue, I cannot say too much here since it is a “grayish” area but I would say the following:

First of all, I can assure you that the device is very very repeatable and is well put together no doubt about it so, don’t be disappointed if you’re unsuccessful the first time! To be successful, one of the most important aspects mostly (overlooked by builders) is “cleanness” I cannot stress enough the importance of it!

Make sure you’ve watched Video 108 paying extreme attention throughout since is stuffed with critical info!

@ 37:04 Timestamp MCL starts talking about the “super clean condition” required almost (I would say) “pharmacy-like” and how he does it!

TIP: underneath the LED driver IC there is a via. make sure you’ve soldered that otherwise, you’re in “trouble” Make sure you test for continuity!

Look under the microscope for potential trace interruptions as the board is homemade (things can happen and you wouldn’t even know it!

Pay attention and double-check / triple-check that all components are soldered in the right place. Mixing resistor values of transistors is easily done!

Verify (again under the microscope) all your soldering joints. Sometimes you can swear that they are soldered but in fact, they are not. Easily done!

One other very important aspect is the component placement procedure required for certain transistors @ 41.24 Timestamp pay extreme attention!

Make sure that when you’ve soldered Q7 you didn’t somehow “zap” it (if you know what I mean) extreme caution is required!

TIP: before commencing the alignment procedure make sure that your VRs are centered first.

TIP: try not to buy components from ” Shady” unknown sources since you’ll almost always get “skewed results” and you’ll be scratching your head!

For the accuracy of the alignment make sure you can either procure or make the required H. value resistors. I know I have.

One last TIP:  sometimes VRs can be extremely problematic (highly dependent on the manufacturing quality) On the other hand they can easily be destroyed when turning them so be very careful with them and the tools used to tune them. I would personally re-test them to make sure they are good and functional.

PS:  I just remembered now! that back then (when the video was released) someone commented on having a similar issue and it turned out that he soldered 2 of the diodes in reverse. 😱 🤢 😡.  Is a good idea to verify those as well.  So again, we can conclude that more often than not most issues are caused by “a human error” and some other times low-quality components being used.

@ovi4 Thanks a lot! It’s kind of you to take time to answer such extensively. By no mean I wanted to suggest is a design flaw, it’s obviously something I did wrong. Of course, I cleaned everything as it’s a low signal circuit. I triple checked everything, maybe i missed something though. About the components, I learned by mistakes, I bought first some transistors from Chinese sites, terrible ideea :-). They sometimes erase the original writing and sell you no matter what. Anyway, thanks again! 

Cheers,

Daniel!