GK3 S1 or S2 not working

Started by philjynx, August 12, 2022, 10:37:14 AM

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philjynx

A few years back I converted a GK3 external to internal. I use a momentary On-Off-On toggle that returns to off when you release it (like many others have done).
I've just rebuilt my guitar and have (so far...) one problem.
With the synth set to increment/decrement patch, only one of those states is operational, i.e. you can only go up or down but not both - I forget which.


Here are the tests that I've done:


On the guitar, multimeter between pin 10 and ground = 950 or so ohms (expected as there's a 1k resistor in series with each of the switches), likewise pin 11 and ground, same result. This suggests that the guitar is wired and working correctly.


Gambling on not hitting pins 12 or 13 as I've already let £90 worth of smoke out of the DRO for my lathe today so that's out of commission till the new parts arrive  - it's too damned hot and I stink, I tripped pins 10 and 11 (separately) to ground and the synth changed patches as you'd expect, so it's not a system setup  issue.


I've checked continuity on both of my GK cables. There are also no shorts.


The hex audio channels are functional.


The rotary switch I fitted for G/M/S works nicely.


Just that one glitch.


One further thing, plugging the lead into the guitar when the synth is already on steps it through the patches, one for each time it gets plugged in. I don't recall that happening in the past. Methinks that's not right.....


Tested on VG99 & GR55.


Crap.

Oh, where's the spell checker gone, I couldn't find it?

philjynx

#1
I don't suppose the short - as measured on the 13 pin socket on the guitar - between pin 10 (or 11) and pin 13 is helping much...

I give up....

Once I've found out where in my guitar this is, I'll rectify it and let you all know whether I've blown that up too!

The lesson here is.... Well, I don't exactly know the answer to that one...

The act of writing "One further thing, plugging the lead into the guitar when the synth is already on steps it through the patches, one for each time it gets plugged in. I don't recall that happening in the past. Methinks that's not right.....
" in my first post gave me the idea to check for anomalous connections betwixt pin 10 and 11 and anything they shouldn't be, just proving that talking to yourself (ok, writing, not talking) can sometimes help.

philjynx


gumtown

Quote from: philjynx on August 12, 2022, 06:04:59 PMFixed.

What was the resulting fix as so required to the as fore mentioned faulting GK device, Sir, my good man, if you please.
Wadjadoo ta fix it ??
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

philjynx

#4
Quote from: gumtown on August 12, 2022, 07:04:51 PMWhat was the resulting fix as so required to the as fore mentioned faulting GK device, Sir, my good man, if you please.
Wadjadoo ta fix it ??
There was an intermittent short between pin 10 or 11 and pin 13 in the din socket on the guitar. I had made a 13 pin socket to 13 pin plug to connect to the GK3 board which lives inside the guitar. You can see the plug here, has red shrink wrap around the epoxy encapsulated pins. I epoxied the socket too, failing to notice the short. Of course, the epoxy renders the assembly unserviceable, cut off the socket, made a new loom and Bob's your auntie's husband.

Nothing fried. Just goes to show the effort Roland go to with protection in their designs.

To the right you can see the rotary G/M/S switch you were curious about. I like it muchly.