Have a Taktile which received slight water damage. Was cleaned out but a key(s) do not play. I tracked this down to what seems like a defective (shorted? Diode?) in the same area as the non-playing keys. I’ve removed the part but they sure are hard to read. It looks like it reads 1SS133ST. Does anyone know what I should be looking for a replacement? I couldn’t find this exact part number.
Like to get this out of my hair because I have a non-reading EPS floppy drive to look at next…
thx
What kind of equipment are we looking at … brand/model ??
It’s a Korg Taktile midi controller 49.
Sorry - I mis-read that Tactile (meaning switch).
In that area you can literally use any small signal diode that physically fits in - ie 1N914 or whatever similar…
Thanks, I’m planning on replacing it with a 1ss133 T-77.
Hopefully, that’s all it needs. I’ll come back after and report how it did.
I did get the Diode replaced but the keyboard still had issues with the one key playing. I started tracing over the entire board. I didn’t find anything until I placed a high output LED lamp behind the board. In the same area there is an obvious trace fault (at least it became obvious with the backlight and magnification). I’m not exactly sure what method would be best to fix this fault, as it is in a weird area right at the key. Clearly, middle left. That moisture really got a few things here.
Seen many times before - and you are lucky because is not located underneath rubber contact strips.
Do the following:
Using a sharp little tool, ie small blade screwdriver, and scrape some of the green lacquer off the area where the trace is still good (yellow section).
Now remove the solder from the bad pin and add a little solder to the bare patch of trace you scraped the lacquer from.
Now then using a tinny bit of small wire, maybe one strand of a twisted copper wire, wrap it around that pin and form it into a “?” (blue) and solder it to the pin and the pice of bare track.
That will fix it.
Unfortunately, it is under the rubber contact strip.
That brown patch and the ring is a distortion in the finish because that’s the area where I needed to solder in the new diode. If you look at the bright light, the key pad on the left looks like it has a broken trace. I’m wondering if I just scrap both sides down a bit, if I could bridge it with a drop of solder. It’s a tiny gap.
Did you check whether it is broken? Put meter between the diode pin and the carbon patch - you should be reading low ohms - less than 100 Ohm
Yeah, it’s a break alright. I have continuality between the upper carbon patch and the appropriate diode pin (the soldered one). I have nothing between the lower carbon patch and the appropriate diode pin (left of soldered one).
Looking at the board ordinarily, The key pads don’t scream out that any are damaged. Same area, lite from front. lol. I wouldn’t be able to tell. Where that piece of trace went? who knows. It’s a microscopic break.
Solder won’t work - there is no copper under the carbon patch!
Best thing I could think of is to remove the lacquer from that piece where the break is then take the finest piece of wire you can find and solder it onto that strip of copper and leaving the wire long enough for it to lay on the carbon patch - hoping for a little spring loading and the rubber strip pushing it down.
Something like this maybe … ?
Oh wow, glad I’m talking to you. it sounds like since this carbon is all that’s there, it would likely have damage from the top down also. I think I’m going to try conductive paint/ink on it. I’m fairly confident since the gap is so tiny this would work. thanks. I’ll return after I get the results from that.
I removed material on the trace to expose copper. On the carbon patch around the bottom edge there appeared to be some copper.there as well (raised lip on bottom of patch). After cleaning up I applied some Caikot 44 to the area. I had my doubts, but apparently the area is repaired. Keyboard is working. 
Brilliant work and well executed !!!
