Author: sgeorge, Posted on: 1 August 2020 23:33
The display is a bit faded.. the buttons are on the way out and the encoder is like a bag of rocks...
First lets break the machine down, and start on the front panel. Its not the easiest thing to remove.
There is a lot of buttons to desolder, and each one has 4 solder points!
It certainly looks a bit daunting, especially since this solder is old, and old solder doesnt reflow as easily. It could be that crappy leadfree garbage for all I know. I am procrastinating, so lets start out with the encoder wheel since it has far less solder joints.
Talk about broken beyond repair! Explains why it was so bad.
So... ugh. back to the switches. After a lot of faffing, we have a bare (sans LED's) pcb, thats quite dirty. I think previous owner spilled something on it.
Monotonous is a good word to describe soldering all these switches back on. Once its done, time to hit the diagnostic menu and do a quick test.
Sorry for the jank picture, I was juggling the phone, the pcb and pushing buttons!
While were replacing the encoder, we might as well do the skip fix.
Here is the schematic of SK414 Rev A, which I have 414 Rev C (the schematics dont have all the revisions).
You can see the two parts of the schematic, the small encoder PCB which is on the right side and on the left is the front panel pcb. It has two 10k pull up resistors.
We are going to add two 1uF electrolytic caps to the encoder pcb since there is no room on the front panel pcb.
I have not clipped the legs off the replacement encoder so I can bend them back and solder the two caps to them much more easily.
Basically, take two 1uF caps, tie the two negative legs together and solder that to the middle encoder pin, and the two caps outside legs to the outside pins.
This will reduce most if not all the encoder noise spikes.
Its ghetto, but works nicely!
And with a couple of donor buttons from our friendly Proteus 2000, since I feel it needs to be honored in some way for the very important donation it is going to make in the next episode.
tags: Audio, E-MU, E6400 Ultra, Sampler
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