Thought I would post my experience with the LD MK IV SE FYI & for the record (FTR??)
MassDrop Little Dot Mk IV SE
Just received my replacement LD MkIV se. The input & output jacks are wired correctly (first one were reversed), but I notice that it too has the warped PCB. Guess that's the way most are made. It's not right & I will strip mine down & get the right length stand offs & clean the solder flux off the board. I resent having to do this, but at least I will have peace of mind when done. This gave me the opportunity to remove the lock on the phones jack too, before it causes an accident. I've included a picture.
Regarding the bent PCB, the tube sockets are 7/16" tall & the PCB stand-offs are 11/32". The tube sockets don't extend through the holes in the top, so the PCB bends when the screws are tightened. It may last a long time like that, but mine is getting longer stand-offs. Cleaned off the solder flux too, so that was a big relief. It is likely corrosive, so it had to go! I'd be curious if all of these units were made with the short stand-offs. I'd like to see inside of an older one that was not made to fill the MD order. These may be using a different tube sockets. Ones that don't fit through the hole in the case or are just taller. Longer stand-offs should take care of it.
In the process, I removed the lock mechanism in the HP jack. Didn’t see any reason for it & worried about causing damage if, somehow, I jerked on the cable.
Update; I added washers under the stand-offs to make their height match the tube sockets. It went back together OK until I tried to install the front panel. It seems that the PCB/standoff dimension is correct & the tube sockets are either too high or too big around to fit the holes in the top of the case. I got the front panel on, but I don't like that the PCB is now stressed in the front.
Solution 1. Replace tube sockets with shorter or narrower sockets.
Solution 2. Enlarge the holes in the top of the case to allow the tube sockets to stick through.
I am probably going with the second solution.
P.S. I hope anyone reading this doesn't think I am overly obsessing about the bent PCB, but my background in engineering & R&D sees this as a serious breaking of the rules of quality assembly. PCBs are not generally made to be bent to this degree, or at all! It will likely fail at some point. I hope for everyone else's sake that it doesn't, but mine is going to be made right one way or another. This thing does sound nice though. I have to give the electrical engineer credit here. It's the mechanical engineer that is to blame. BTW I think you should be able to disable the locking phone jack without opening the unit up. Not sure if the wires are long enough. I can elaborate if anyone wants to do it. It's easy.
Update: If anyone cares??? I finally enlarged the tube holes in the chassis to accommodate the tube sockets. (Solution 2) Used a Dremel, but ended up finishing with files. The large holes need to be a bit over 1" & the smaller ones about 3/4". I thought that I could use the brass plate as a guide, but the large holes need to be a bit larger than the holes in the brass cover & the small holes a bit smaller. Anyway, it's all back together & working, with a flat, unbent, PCB. One of the hardest parts is learning how to maneuver the wires to get the board out & then to get it back in. When you get the wires arranged properly, the PCB assy. comes out & goes in smoothly. Glad that's over, as it was bugging me that the unit just wasn't right. The amp is much happier now. I would like to tell you that it sounds much better with an unstressed PCB, but I really can't tell a difference. Also enjoying the non-locking jack.
Talk all about Little Dot products!
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