Motorhome Maintenance

Electrical

January 2009

Electrical problem with Calria EVS30/20 battery charger unit - Not working on 230V Mains.
Discovered fault is with charger. Dealer was unable to repair it, and advised cost of replacement was around €600. ! Sent unit back to manufacturer Calira, in Germany. Advised cost of repair at €470, now same price as new charger.
Declined that offer, and had unit returned.
Contacted Calira by email, asking for circuit diagram(s)
Received circuit diagram and physical layout files in pdf format.
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Calira EVS30-20 Operators Manual.pdf (766 kb)
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From what I can see, it is a two-transistor forward converter SMPS. The SMPS is controlled by a single TDA16888G IC
There is also a PIC16F872 which I think controls the charging cycle, and also some logic which decides whether or not to operate the final relay to connect the PSU output to the external load

April 2009
I have made several attempts at fault-finding on this Calira EVS30/20 unit, but infortunately I cannot track down the source of the fault.
I read up a lot on SMPS repairs & common faults, which suggested the electrolytic capacitors are common faults but not this time. I replaced the electrolytic capacitors on both Primary & secondary side of the transformer, but it made no difference. I checked all the diodes, resistors and bridge rectifiers, but again could find no faults.

When mains is applied, the output relay does operate, which suggests it is generating some voltage at the output, but there is a noise from the unit, like a white noise. Sounds like a static hissing sound. I listened to this sound through a plastic tube to try to identify where it was coming from, and found a couple of small tanatlum capacitors seemed to be generating the noise, so I swapped those for new ones, but still I have the noise. After checking the circuit diagram it seems these capaitors are simply noise filtering to earth, so I removed them totally. Still the same noise.

for now I have given up on repairing this unit. ... more to follow