An example of text-fixing and repairing of a film in a phototypewriter

When the image forming machine ECRM 1030U in our factory suddenly appeared text distortion when the film was issued, that is, the text was elongated in the direction of the film, causing the entire version of the heart to be large. Under normal circumstances, this phenomenon is caused by the instability of the motor speed. How can we repair it?

First, we adjusted the speed adjustment potentiometer above the circuit board. After several adjustments, we found that we could gradually adjust the text. However, after waiting for a period of time, the text began to become smaller, which led to a reduction in the overall version. Then return to the adjustment, such as adjusting the distribution, the text has become larger, repeated many times can not solve the problem. Then, we also think that the phenomenon of unsuitable belt tightness will cause this phenomenon, but many adjustments cannot be eradicated. Finally, we consulted the maintenance personnel and learned that the motor speed control code board may be damaged and needs to be replaced. But to replace this circuit board, the price is not expensive, the key is to find this circuit board for a time. Unfortunately, we had to remove the circuit board. After careful study, it was found that there are two transistors (the model number is TDA204D and BD X 34C) which are arranged side by side. Although heatsinks were installed, the panels around them were discolored, and it was suspected that the heat dissipation effect was poor. So we decided to add another heat sink to each of them. Test machine, the problem can be solved. Until now, this failure has not occurred.

From the above maintenance process, it can be seen that the main causes of this failure are the time when the equipment is used, the aging of the components, the deterioration of the thermal stability of the transistor, and the occurrence of drift, resulting in unstable motor speed. This fault is not difficult to solve, but it is not easy to think of when repairing, easy to take the detour, most of the thought is to replace the circuit board. Our program is economical and practical, written for your reference.