Discussion Category:  Centrifuge

power supply failure

ANYONE HAVE A SERVICE MANUAL WITH SCHEMATIC FOR EPPENDORF 5415D CENTRIFUGE?
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DFL
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avatar placemarkReply by
Markiyan

I've managed to fix mine without board diagrams/service manual:

(Assuming the VFD's are OK), basically low  voltage psu in this model consists from two galvanically isolated 12V sections - one for display controller and one for VFD controller.

Both are powered from a high frequency transformer, which is known to fail/develop shorted turns.

They also have LM 5V linear regulators (to get the 5V DC) from the 12V DC (IC803 is for 5V VFD).

In my case the display section was getting the 17-20V (on C811 cap) instead of 12, which had fried the linear regulator (near 6V cap above C811). Since it is difficult to get/make the replacement tranformer or to diagnose the SMPS voltage regulation fault - I've just gutted the 12V 2A walwart (SMPS type), mounted it inside the centrifuge, connected it's AC input to the mains power input on the PCB, and fed the output to the 12V section of the circuit, and ditched the tranformer (unsolder / cut the trace).

to get the missing 5V from 12V - I've used 5V buck DC-DC converter (from 5V USB CAR charger).

If fully removing the tranformer - make sure to keep the galvanic isolation of both PSU sections - use two separate 12V smps-es.

PS: adjustible LAB PSU (0-30V, up to 2A) was ESSENTIAL for diagnostcs.

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avatar placemarkReply by
DFL

Hello, nice you figured it out. I don't remember the outcome of that one I had but I didn't get a schematic. 

 

Thanks for the response though. 

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