[SOLVED] Weird issue with some step keys

Hey guys. Just Finished up a build and everything works well except a couple step buttons (namely 9, 10, 13 & 14)

They're acting all around funky. In pattern write mode, the first time I press any of these buttons, it will activate them properly, but then any adittional presses will have no effect. I can continuously press them and they will not turn off, then a few passes of the active sequencer through them will either turn them into accents or turn them off, kind of randomly.

When I start the Nava and press Play, step 9 starts off lit. The first time the sequencer plays it, it becomes accented, then nothing else happens to it on additional pass throughs. Step 13 begins flashing after the sequencer has been running a little while.

Also, in pattern write mode, if I press Select Instrument, Mid Tom will immediately be selected. If I try to select any other instrument, it will immediately bounce back to Mid Tom within a couple miliseconds unless I release the Select Instrument button faster than that (pretty much pressing it with an instrument key simultaneously.)

I have desoldered and resoldered and no dice. Looking for any help on this, as its become pretty frustrating. Any ideas what area to focus on? It seems like a software issue, as no resoldering I have done has helped.. I will try to pop the non-functional step keys out and swap them with ones from the working steps just to confirm that it is not an issue with those buttons. I dont think it is though, since the problems dont seem to be something caused by faulty hardware. When I press step 9 for instance, it will sometimes also turn on step 10. The first press of these also always works, so its not like contact is not being made - its just the way they behave once pressed is not proper.

Thanks!

Just realized that my PSU is 16VAC, not 15V. Any chance this would cause any issues? Seems weird since it all works well except these issues with the sequencer..

Just checked and these problems still persist even with no step keys installed at all in these positions. Does anyone know which parts on the sequencer section could cause spazzy behavior like this? I will take a little video in a bit to better describe the behavior. Anyway, its not an issue with the step key hardware itself.

Here is a video showing the issue

I'd be looking around IC104 to start with. IC104 is the shift register that loads the button states of the step 9-16 keys to the MCP.

If you have installed the chip in sockets the easiest thing to is to swap IC100 and IC104. IC104 in the casing the issue the problem should move to the step 1-8 group of keys.

If you haven't socketed the chips order a new 74HC165 and replace IC104.

This is what I would do anyway.

Rowan wrote:I'd be looking around IC104 to start with. IC104 is the shift register that loads the button states of the step 9-16 keys to the MCP.

If you have installed the chip in sockets the easiest thing to is to swap IC100 and IC104. IC104 in the casing the issue the problem should move to the step 1-8 group of keys.

If you haven't socketed the chips order a new 74HC165 and replace IC104.

This is what I would do anyway.

Swapped IC100 & 104 and the problem still persists :/ thanks for the start thouh!

Solved the problem by reflowing the associated caps. One of them was not making a good connection and messed up all 4 keys! Now working 100% beautifully!

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