SM 52


Well-known member
Starting cold press this morning. Makeready first job with no problems. Start saving and ran approx 200 sheets and press hard stops. Show Main drive: Malfunction. It has done this 3 more times.
Location is 90 which I'm assuming is the electrical control cabinet. No fuses have blown out and no breakers are tripped. Waiting on answer from Heildelberg. Any ideas?


Well-known member
Hi sir:

Normally, this machine has electronic board BLT4, with many electronics components.

1) PTC resistor for temperature, can be defective for possible increase temperature of main motor.

1a) Review all power supplies of the machine IF they are in TOLERANCE, like +15 -15

2) interference Filters

3)Bridge rectifier, would be Leakage or defective. they rectify the three main line 3 phases.

4) control for Brake release.

5) Rectifier Module GRM 24 +48Vdc

6) Chopper Resistor, for to provente uncontrollable rise of intermediate circuit voltage

7) And possible defective Power Transistor like IGBT +Thyristor.

8) Maintenance Motor: Lube+exchange of bearing, and overheating winding(NO burning, the winding must be recover with Isolate Barniz for to protect the internal winding, and possible failure by overheating winding!)

In short time to go the Main Motor, to the Shop Maintenance and Test the Electronic board BLT4 and associates.

Mobile+WhatsApp:+505 8861 1441


Well-known member
Thanks for info. I thank you may be right with your analysis. I corrected the problem by unplugging the main drive motor and plugging it back in. That must have reset something internally. No problems since then. Thanks again.


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