Korg Forums

[yoshi88]

The previous owner tried to repair their own joystick by replacing it with another.

It does not work!

I have replaced the CR2032 battery and replaced the FDD and restored factory Prog / Comb.
complaint : that this KORG T3’s overall pitch is unstable & goes out of tune.
The joystick has a problem. The Y : + / - axis works but the X: + / – axis does not work correctly.
- also the joystick changes input + - values on parameters once they are highlighted.
- Also changing the 2032 battery @ 3.35 V still reports low internal battery error message. Checking the battery and still 3.35V!

- When the joystick wire harness is removed from circuit board... Error message disappears and tuning is stable.

IT looks like this joystick was replaced before! But is think the wiring sequence is wrong.

Do any of you have the wiring sequence for the 2 Joystick pots?


Thanks
_________________
Kronos 2 88
M3 61 expanded
Triton Extreme 88 & 61
Triton PRO X 88
Trinity V3 61
O1WFD 61
T3 61
M1 61
03R

[T3owner]

Are you sure the battery polarity is correct?

This might help with that and the joystick issue:
https://elektrotanya.com/korg_t-series_t1_t2_t3_sm.pdf/download.html
_________________
Korg: T3EX, 05R/W | Yamaha: Motif XF6 and XS6, A3000V2, A4000, YS200 | Fender Chroma Polaris | Roland U-220 | Etc.

[yoshi88]

The polarity is correct. The battery was checked as 3.37v. The positive is gacing up.

The previous owner replaced his joystick but soldered the incorrect sequence of wires. This is the problem. Thanks for the T3 SM. the color code is not defined on those pages.

I will search for an image of both X and Y axis pots.
_________________
Kronos 2 88
M3 61 expanded
Triton Extreme 88 & 61
Triton PRO X 88
Trinity V3 61
O1WFD 61
T3 61
M1 61
03R

[T3owner]

[yoshi88]

"Are the Progs and other data being retained when the T3 is powered off? "

Yes... all global settings / PROG / COMBI retained.
Lithium 2032 = 3.3 V!

When harness connected, programs still retained. Erratic joystick behaviour creating unstable Master Tuning values and / or other selected cursor values.

Thank you …. will trace pin outs and post.

Once corrected pin outs are set and joystick tested I will know if the TWO pots are working properly.
IF not I hope to find a suitable pot replacements on digikey.
_________________
Kronos 2 88
M3 61 expanded
Triton Extreme 88 & 61
Triton PRO X 88
Trinity V3 61
O1WFD 61
T3 61
M1 61
03R

[T3owner]

The voltage at the battery isn't necessarily what reaches the rest of the circuit. The static RAM chips can retain data at much lower voltage, typically 2 volts. So the warning of low battery voltage might be correct even if the data is retained.

Page 23 of the PDF shows BATT1 (CR2032) and related components. The positive side of the battery connects to R20 (1 Kohm), through that resistor to diode D3, then through the diode to the junction of D2 and C22 (10µF/16v). The D3/D2/C22 junction connects to the Vcc pins for the SRAM chips.

The thing to determine is what the voltage is at that junction, with power to the T3 turned off. It will be less than 3.3 volts, due to a drop across R20 and D3. That drop will be related to how much current the SRAM chips are drawing, and the condition of C22. If C22 is electrically leaky, the drop may be excessive. Also, if D3 or one of the SRAM chips is defective, or R20 has gone significantly up in value, the voltage will be too low.

However, if the voltage at the D3/D2/C22 junction seems high enough, then the problem can be at the ADC circuit that does the comparison based on REFerence voltages.

Note that REF and REF2 voltages relate to both the joystick operation and measurement of the battery voltage. So do other functions - for instance, aftertouch. Is that working correctly?
_________________
Korg: T3EX, 05R/W | Yamaha: Motif XF6 and XS6, A3000V2, A4000, YS200 | Fender Chroma Polaris | Roland U-220 | Etc.

[yoshi88]

After touch is working!

Rather interesting previous soldering work on this joystick by ??? Previous repair had solder dripped from terminal directly INTO the "X" pot. through the vent , where it made contact with the sweep board trace
I disassembled the X pot , removed the cover, carefully removed the solder bead that had melted into the plastic with a dental tool. That solder bead that made contact with the pot board, may or may not have affected the pot's operation.


The Y axis operation is normal .
The X axis operation does not result in pitch bend. ( once the JOYSTICK parameter value is set in the PROG Edit )

Joystick Pitch: ERROR: So if the pitch bend is set for 2 in joystick mode, there will be NO pitch noticeable!

Aftertouch = NORMAL: IF aftertouch is set to 2 , the pitch WILL respond by going up 2 semitones!

However, once again, with joystick harness connected to board.
Low voltage error message! ( V = 3.3V )
After Touch is normal.

Joystick X axis is unresponsive from a sound perspective.
Joystick X axis CAN alter Cursor values.
Low Battery Error

Also, when the cursor is located in EDIT or Global parameter locations,
the joystick does seem to enter and alter values in the highlight areas. So it appears to behave like a controller that can input values for example +/- 12 etc.

The Zeroing in of this is out of calibration.

Is there a firmware /software setting that needs to be checked?
Where does one find the JoYstick control features to verify normal software settings?
I can't assume the factory disk has never been overwritten.
_________________
Kronos 2 88
M3 61 expanded
Triton Extreme 88 & 61
Triton PRO X 88
Trinity V3 61
O1WFD 61
T3 61
M1 61
03R

[T3owner]

Joystick X-axis operation should not affect parameter values - the "VALUE" slider should do that. Does it?

IC21 (74HC4051, SP8T analog switch) is supposed to select one of eight inputs, the output being sent to the ADC (A/D Converter). The eight inputs include the joystick X-axis (pitch), Value slider, aftertouch, battery, etc. Which input connects to the chip's output is determined by three digital select pins.

Based on your description of the joystick X-axis and battery test operation, it appears that IC21 isn't properly selecting which of the eight inputs should be connected for a particular mode of operation. That could be either due to IC21 being defective, or the data on the three select pins being incorrect.

The area of the circuit I'm referring to is shown at the bottom left corner of page 24 of the SM PDF I linked to. For additional information, I suggest that you download a data sheet for the 74HC4051 (https://assets.nexperia.com/documents/data-sheet/74HC_HCT4051.pdf). Look at the select pin voltages (high/low on pins 9, 10, 11), and determine if they change for the various modes. If you can't be sure, it might be worth changing IC21 anyway, and see if the joystick and battery test problems are resolved.

You might also try running the diagnostic checks, PDF pages 36-40 {manual pages 34-38}. Perhaps it will turn up something not already obvious.
_________________
Korg: T3EX, 05R/W | Yamaha: Motif XF6 and XS6, A3000V2, A4000, YS200 | Fender Chroma Polaris | Roland U-220 | Etc.

[T3owner]

By the way, you can check IC21 (74HC4051) operation by looking at the function table on page 5 of the data sheet I linked to.

For Pitch (joystick X-axis, connected to IC21 pin 14) to be selected, pins 9 and 10 should be Low, Pin 11 should be High. If they are, and Pitch Bend doesn't work, then IC21 is likely bad.
_________________
Korg: T3EX, 05R/W | Yamaha: Motif XF6 and XS6, A3000V2, A4000, YS200 | Fender Chroma Polaris | Roland U-220 | Etc.

[yoshi88]