PM 74-4 mid error

hi fix an mid display of pm74-4, the original error was no 5vcc, the power source was damaged. I put a external buck module and the display works (show heidelberg when power on). i install the display on machine and he works showing error 90 and dont show some information like suction air, gripper bite display and pull lay adjustment display.
i need some help to fix this error
sorry for my poor english

 

Hi sir

is the display compatible with Heidelberg?

the external buck module, can work partially, BUT if the components are NOT compatible, will have problem.

Since the EPROM2 can be NOT compatible or Corrupts.

You must have sure, if the module that you installed is o.k according with the Parameter of factory, they use SMT. (new Tech).

 

Hi sir, thanks for the reply.
The display had been working on the machine for years. last month it failed to show nothing. I did his analysis and the 5v source responsible for feeding the microcontroller was damaged. The most viable repair option was to install another buck converter to supply the 5v. After the repair, the display returned to work showing heidelberg when turned on. His circuit is composed of an 8052 microcontroller, ram and a rom. it receives data from a 485 line and an optical coupler. After the tests I installed it on the machine and it shows the printout counter and the speed, and the error code 90. but the other data it doesn't show.
the code of display is: 00.785.0224
Another version of the display uses the ci lm2576 to convert the 24vdc supply to 5v. The circuit I used uses the ci lm2596 and was set to 5vdc. it is a simple buck converter. His original circuit uses a pwm controller with a mosfet.

 

I made two videos that show the problem are on youtube:

 

Hi sir;
Thank you by his information.However i believed after checking my tech documentations;

1)You test it the power supply for the MID (Display Monitor) only for +5Vdc, however the tolerance for the power supply in Vdc is 0.7% up or down. please use the Schematic electrical Diagram

2)The power supply generates the 5 V DC supply for
the printed circuit board from 24 V DC. If the 24 V
DC drop below approx. 16 V, the power supply will
trigger a reset on the board. Afterwards the CPU
starts a self-test of the MID.


3) Test in the module NTM

Voltages
The power supply module produces the following
stabilized output voltages from the non-stabilized
input voltages via switching controllers:
DC 5V
DC 24V
In addition, the voltages + 15 V,- 15 V are produced
from the 24 V via a DC-to-DC converter.
The output currents are limited internally. The maximum
output currents are:
24V 8A
5V 10A
+15V 0.2A
-15V 0.2A

Good luck

 

Hello Mariza,

Interesting fault, have you been able to fix it? I have worked on a very stubborn fault of the MID for a customer but the problem wasn't similar, for this problem I would try replacing the micro controller and the RAM, it is possible when the buck converter failed it damaged either of those components. The serial data is stored inside the registers on the micro controller may be they got damaged, just a guess. Let me know what happens.

 

Pls do share the picture of the repair also, i do not understand what you mean by an external buck converter, the pre-made buck converter modules that you get in the market have a lot of ripple at the output and can cause havoc with communication at times