- Thread Starter
- #181
Here is the offending screw:
Wow... Does it seem like a screw that could have come loose on it's own or would it have to be loosened by a screwdriver by hand etc?Here is the offending screw:
View attachment 228311
Definitely looks like it can come lose by itself. It goes from loose to not with smallest turn of the screw (not enough threads per inch). And it is awkward at that because you have to have a small screw driver to grab it inside. I am sure it was borderline tight and came loose in shipping. If I didn't know what to look for, you would not know that it is loose. I moved the wires around and realize that the washer for the grounding wire would slide around under the nut.Wow... Does it seem like a screw that could have come loose on it's own or would it have to be loosened by a screwdriver by hand etc?
Funniest places that manufacturer faults can pop up and show themselves... lol.Definitely looks like it can come lose by itself. It goes from loose to not with smallest turn of the screw (not enough threads per inch). And it is awkward at that because you have to have a small screw driver to grab it inside. I am sure it was borderline tight and came loose in shipping. If I didn't know what to look for, you would not know that it is loose. I moved the wires around and realize that the washer for the grounding wire would slide around under the nut.
Yes. Or as I suggested to the owner, to put some nail polish on it to keep it from turning loose.EDIT: Maybe a lock washer would be good?
An ancient 'trick' used by experienced folks in many of the tech school/trade school taught industries that is not 'officially' taught but is a word of mouth (or self thought) innovation that works for a temporary(permanent?) 'emergency' repair, many times while waiting for the super glue.Yes. Or as I suggested to the owner, to put some nail polish on it to keep it from turning loose.
Yeh, I learned that from my older brother decades ago. Nice way to use up your wife's finger nail polish that she is not using.An ancient 'trick' used by experienced folks in many of the tech school/trade school taught industries that is not 'officially' taught but is a word of mouth (or self thought) innovation that works for a temporary(permanent?) 'emergency' repair, many times while waiting for the super glue.
YEP! It also seemed to work well on "red bug" (chiggers) bites.Yeh, I learned that from my older brother decades ago. Nice way to use up your wife's finger nail polish that she is not using.
We also used to use clear ones on case screws to detect if the customer had opened the unit!![]()
Great to see. I am immensely looking forward to the re-run.Found and fixed the problem! There is an internal RCA jack that connects the power amp to pre-amp. There is a grounding screw for the shield. It had come lose. Tightened it and here are the results:
View attachment 228310
This is power amp only although before the fix was nearly as bad as the full amp I tested in the review. I will put it back together and re-run all the tests.
Use blue removable threadlocker. Not cyanoacrylate.Dab of Loctite?
PS I am really glad the source of the poor performance was tracked down! The originally measured performance was abysmal... on par, and maybe even worse (!) than an unrestored example would manifest!
I service music and audio equipment. Just the other day I had a customer with a recording studio messaging me because he was trying to tune the oscillators of an old Oberheim analog synthesizer by ear. Another engineer told him to put nail polish on all the internal pots and coils. Bad idea. Not like someone broke in and opened up his synthesizer while he was sleeping. The oscillators drift for various reasons. Parts age, moisture, other components drift out of tolerance etc. And it really needs to be done with test equipment. Everyone is trying to fix everything themselves these days. They expect free technical info and don't value anyone else's time and experience.Yeh, I learned that from my older brother decades ago. Nice way to use up your wife's finger nail polish that she is not using.
We also used to use clear ones on case screws to detect if the customer had opened the unit!![]()
I was deliberately vague.Use blue removable threadlocker. Not cyanoacrylate.
Found and fixed the problem! There is an internal RCA jack that connects the power amp to pre-amp. There is a grounding screw for the shield. It had come lose. Tightened it and here are the results:
View attachment 228310
This is power amp only although before the fix was nearly as bad as the full amp I tested in the review. I will put it back together and re-run all the tests.