Controller schematics

[C9021]

Hi,

I have become an owner of Case 9021 excavator. The manufacturing year is just before millenium in 1999. It has symptoms of a broken controller - no automatic engine control and no leds visible inside the controller case. Similar (exactly the same?) excavators are Sumitomo SH200 (1-2) and Link-Belt 2800Q. I believe also smaller models such as Case 9013 and Link-Belt 2700Q has the same controller.

The controller has markings SMCU-5 KHR1794, and replacements are easy to find from China.

I have also acquired the service manual of Case 9021 that can be found from multiple manual download pages (7-22341), but previews show they are all the same - and missing the big fold-out schematics included in the original printed version of the manual. There is a schematic in my manual to measure and troubleshoot the motor driver and the throttle motor - but these are working.

Now I am looking for someone that has these prints or know how I can get my hands (eyes) on them so I can measure that I have good wiring before I shell out money to the Chinese - (and wish I get a working controller)

Secondly if anyone knows anyone that has successfully replaced a controller - How pain in the a?? it is to program it and get one working?

Thanks,
Samuel

 

[old timer]

Hi Samuel,

Before replacing a controller, I would look at the bypass switch. When they fail you get no power to the controller.

Hope this helps.

 

[C9021]

Thanks, interesting information, but I fail to find the location for such an item. There is a sensor connector with a broken wire in the bottom of a boom cylinder that I was going to fix after I get the controller running. But schematics would really help me to understand how this all works together.

 

[C9021]

Actually you must mean the backup throttle switch because today I tinkered things a bit and removed the seat for a better troubleshooting enviroment. And as it happened the both leds are lit inside the controller, but still no functions available. So the controller is the most probably cause.
Does anyone have a meaning for those leds? One green and one red. Both are on when trying to operate normally.

 

[C9021]

Took a leap of faith and ordered a controller from Alibaba. I also found those specific three-wire connectors from Aliexpress, so ordered them, too. I'll report how things will go after install.
Any hints what I should expect after plugging in? Those colored leds still needs an explanation - what are they for?

 

[old timer]

The by-pass switch is at the rear of the right hand console, next to the manual throttle toggle