[supremetwo]

Re: ARZ853H control board circuit.

The basic circuit turns out to be ‘Capacitative half wave rectification post-zener’ with the added complication of dual outputs.

Presume it’s common for the control boards of this type of appliance?

[supremetwo]

Re: ARZ853H control board circuit.

electrofix wrote:also they never operate relays at the correct voltage to stop coil heating and failure. would expect a voltage lower than 18v

think i can see it now . the .68uF (C6) cap is acting as a dropper (capacitive reactance) change it Dave

Dave,

Spot on with the .68uF – changed that and the relay coil volts went up from 13.3v to 20.9v.

Thanks so much for pointing me in that direction.

Regards,

Malcolm

[supremetwo]

Re: ARZ853H control board circuit.

There are two 12v zeners in series d22 and d23.

Thanks for the .68uF suggestion – that was low on my suspect list.

However, I’m now getting 13.4 volts at the relay coil so I’ll try a new 100uF first and see if that gets closer to your suggested 18 volts.

The rest of the circuit seems fine with fridge and freezer temperatures as set.

Malcolm

[supremetwo]

Re: ARZ853H control board circuit.

Hi, Dave

The zener diodes are part of the bridge 2x12v plus 1x 5v seems about right for a 24v relay coil.

I replaced the 100uf capacitor but still around 13v at the coil, though its enough to operate the relay now. But the cap was from some old stock in my bits box – I’ve ordered new ones and diodes.

Board picture and component details (pdf):-

https://www.dropbox.com/s/l5il1w6ff95sl … d.pdf?dl=0

Malcolm

[supremetwo]

Re: ARZ853H control board circuit.

Hi, Dave

Thanks

I already have the circuit of the appliance.

No obvious sign such as a burned component.

I’ve now scanned the PCB and am in the process of id’ing the components and drawing the circuit.

I suspect that a diode is down in one half of the bridge that feeds the compressor relay coil.

Malcolm

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