Regards,
I have 6 diodes in laser printer, some with an EDC tag, some with an EDN tag on the casing.
When I test them with the multimeter in the test area of the diode, they all show endless resistance in both directions "open".
I did not find some data on the Internet, possibly are some temperature diodes. Otherwise, they are black in cylindrical shape with a white ring for cathode designation, 2.5-3 mm in diameter and white letters EDC or EDN on casing.
These diodes are used in a laser printer that is connected to a sponge transfer roller that is powered and serves to transfer paper toner to make letters from an optical OPC cylinder over to paper. However, I found burned 20,7k ohm metalfilm resistor. Instead of 20.7 k ohm I put 22 k ohm and now I get the error "917 service transfer roller", it means something is still burned. I checked capacitors and other resistors and they are fine, but I can not check this EDC and EDN diodes with multimeter, it always shows "open" on both directions, how to test them?
The problem with printer is that the inprint is faded because there is not proper voltage on sponge transfer roller. The cartridge and OPC drum are new. Problem is in circuit board. Printer is Lexmark E342n.
Thank you