Lelit Mara X PL62X Gicar box schematic

repetto74

Hi,

I have recently repaired my faulty Mara X with the replacement of the PID control box which went bad (Lelit code 9600096).
I have electronics skills so I would like to give a look at the faulty board and try to diagnose what is wrong there.

Does anyone knows where I can find the electronic schematic of the GICAR control box used in the Mara X? :?:

Thanks.
Rick

DavecUK

repetto74 The only people with the authority to give you that are Lelit. The boards are customised.

repetto74

Indeed it seems that nothing is available on the net. Well I may try to do some retro-engineering and spot what is at fault here. It is a pity to throw the entire pcb for maybe just one single component.

DavecUK

repetto74 I suspect, but don’t know for sure, that it’s not a component, but one of the connectors to the outside world, usually the connectors to the temperature probe.

repetto74

Could be. I am checking the board for any visual indication before probing.

The black connector marked CN5 is for the SSR control and the CN3 is the temp probe. At a glance soldering looks good and connectors are not damaged.

Although the CN5 + pin is connected to the pin marked JP2 on the left where the orange ribbon is soldered. This ribbon connects the power board and there I see something weird with a diode which does not seem right when I probe it.

DavecUK

repetto74 I see something weird with a diode which does not seem right when I probe it.

What’s weird? The connectors for temperatures and components connected with it are favourite.

MediumRoastSteam

DavecUK The connectors for temperatures and components connected with it are favourite.

https://coffeetime.freeflarum.com/d/2881-lelit-mara-x-pl62x-steam-overpressure/20

repetto74

The diode has a voltage drop of .350V on both sides which is not normal reading for a working diode (should be around .700 and overload on the other side).

The diode is the one partially visible in the picture juste below the JP1 marking on the powerboard. There are two diodes there, it is the one on the left side and connected to the +12v of the SSR relay.

Those are smd diodes with no markings on them. There are 4 of those which looks visually the same and this one does not have expected voltage drop when probing.

Gagaryn

repetto74 The diode has a voltage drop of .350V on both sides which is not normal reading for a working diode (should be around .700 and overload on the other side).

The most likely explanation is that the diode you are probing is a zener which explains voltage passing both ways. The lower than expected voltages are likely due to it being tested in circuit; most likely there is a resistor in parallel with the diode. I’m assuming these diodes form part of the voltage regulation node of the power supply? To reliably test the diode, you really need to lift it from the board - otherwise it’s easy to get misled…

repetto74

Gagaryn I had this doubt indeed, as you said it could be a zener diode despite the fact it looks exactly the same as other diodes on the pcb which voltage drop tested ok. Actually those may be all zener diode with the same spec. I could not identify any resistor in proximity of this diode.

I have all required tools to unsolder it from the board and probe it out of circuit. I am focusing on that area as this is the circuit that provides continuous +12V to the SSR with no regulation. I believe something is wrong there and I think I can discard the circuit of the temp probe as those +12V where immediately sent to the SSR relay to turn the heater on with no prior check for tank water level etc etc.

repetto74

Out of circuit this diode is probed as good (.730 voltage drop and Overload with reversed probes). I soldered it back and moved on :-).

Difficult anyway to backtrack things without a schematics.