Harvester keypad. No lights

[will62]

Re: Harvester keypad. No lights

I think that was a type-o. Here's a TLC5943.

[petehall347]

Re: Harvester keypad. No lights

he said they are TCL5943 .couldn't find much on them . i guess they will need some sort of supply voltage to work .

[CapLeaker]

Re: Harvester keypad. No lights

Are those 3 color led's? I see 6 leads per led, and what looks like 3 seperate emitters in each led.?

he did state that they are RGB
"Board B has all the logic to drive the CAN signals and the LEDS. LEDS seem to be RGB, as they are driven by several pins, and I have seen them flashing in different colors."


I am guessing that that one LED is like a back light. When you press the button it changes color for example to green (for the function being engaged indicator). Now you have nothing, no backlight and the indicator doesn't change color either when pressed, correct? LED's are current controlled, not voltage controlled. What is the part number on these LED drivers?
Did you ever compare the Test Points between the good and bad board B? Maybe it is something simple like a missing voltage or a shorted SMD cap.

[R_J]

Re: Harvester keypad. No lights

Are those 3 color led's? I see 6 leads per led, and what looks like 3 seperate emitters in each led.?

[edugimeno]

Re: Harvester keypad. No lights

pin6 of the can driver - follow the trace and it looks burned in the foto

Thanks but actually the CAN messagimg functionality is working 100%, its only the leds what are failing. I dont see where it might interact.

Btw this is a recurrent failure on these boards, the dealer has sent dozens of them to the trash due to the same failure. He hasnt found anyone able to rrepait them so far so the customer has to purchase a new one (1k)

Thanks

[stj]

Re: Harvester keypad. No lights

pin6 of the can driver - follow the trace and it looks burned in the foto

[edugimeno]

Hi There. I have this weird device that is not fully working.
It is a keypad used to control several tools in a harvester. It uses CAN bus to communicate with the devices in the machine.
When it is powered on, it should flash all the buttons for a second, and then only the functions that are active, should remain lit. If you press a button, it should send a CAN msg and corresponding light behind the button should turn on/off.

The broken keypad still keeps its control abilities 100%, but you have to work blind, as the leds behind the keys don't light up at all. No powerup test flash, no working lights, nothing, but when you press a button, the specific tool is activated, so CAN connectivity seems ok.

Inside, it has 2 boards.
Board A (check pics) has connections to harvester. Only 12V, GND, CAN-H and CAN-L are used in a real harvester. It has several transistors, probably for functions that are directly driven by the board, probably connected to the spare plugs, never seen them in use.
It has a small connector to board B. Connector only has GND, VCC, CANH/L and 2 more unknown pins.

Board B has all the logic to drive the CAN signals and the LEDS. LEDS seem to be RGB, as they are driven by several pins, and I have seen them flashing in different colors. Each key has 2 leds. One helps you locate the function it does at night, other turns on/off whether the associated tools is activated or not. This is the faulty board, when I use this board on another Board A, it still fails.

IC's on this board are:
1xTLE4473 GV53, this is a LDO dual output regulator, for 3.3v and 5v (5v seems to be inhibited and unused)
2x762T, these are power FET switches. I think one activates TE11 and other activates TE12.
1xA1051/3, this is the CAN line driver, to interface with microcontroller
2xTCL5943, these are 16 output LED drivers
1 microcontroller
1x93LC86, this is an EEPROM for the microcontroler

As everything but the lights seem to work fine, I believe the problem is in some current driver for the LEDs set, but I can't tell how it could be driven.

I have a complete working set and another broken set (only board B is actually failing, as tested exchanging boards)

Can you provide any help on how to diagnose what could be wrong?

I uploaded pics of both boards (you can ignore board A) on both sides, and one of front B with annotated IC's markings

Thanks in advance!