I have an almost unused Ring RCCB322 battery charger it has 12 / 24V charging option with 12v only Engine Start. It is out of warranty. I used it last night for the first time ever in start mode, a 12V visiting horse lorry had failed to restart. Unfortunately I failed to remove the lead within 30 secs of the lorry starting which it did immediately, a little smoke came out and it now no longer works. I spoke to Ring they said they did not supply parts or have a repair section they also said they did not have a circuit diagram.
I opened the unit there is almost no sign of overheating just a little melted tape on the transformer it also smells fine. The centre tapped transformer gives 10v-0-10V or 20V-0-20V but without a load the DC output is about 0.5V. I suspect the four Tube rectifier between the two aluminium plates secured with the red security nut on the VEC078 V00C have been destroyed. Is this repairable and is it likely the voltage control circuit is still working? Help and suggestions will be appreciated.

 

Please find attached a couple of extra pictures

 

Sorry pictures did not arrive!

 

Pictures should arrive this time!!

 

The photos don't seem to help, except that I think I see, "button" rectifiers. You are right in that the brains don't usually smoke, the power parts do. The problem here is that you are going to have to do some measurements to track this down because the wisp of smoke is long gone.

You need to measure from that kind of centered wire on the transformer to the other 2 wires, one at a time, in, "AC voltage" mode. That's the dividing point between high voltage and low voltage. (You're on the low voltage side.) After we see if you have the transformer working, we'll decide what to measure next. And don't forget that the 12v/24V switch might be bad. You will have to wiggle it from time to time during this process to see if it affects the measurements.

 

Thank you for your help #12. I took the measurements about the centre tapping with 12V switch setting selected both windings measure 10V ac and when switched to the 24V setting increase to 20V ac each. The transformer does not smell cooked so think it is fine. These voltages are present on one side of the button diodes but there is negligible DC voltage on the output side. With the meter set to resistance the diodes seem to be open circuit whichever way round the meter is connected. Does anyone know a good place to buy new button diodes and have any idea on the current value required?

 

The RAC heavy duty engine starter / charger is similar to this model and the internal components look identical.
The diodes on that charger are MIC RA501, 50v 50 amp devices.
Replacing them is shown in detail on http://www.letonkinoisvarnish.uk/RAC_ChargerRepair_6.html

You also need to check the two MOSFETS IRF3205 (International Rectifier) on the control board heatsink as these are the main failure components for these chargers.
Repair details and circuit drawings of the power part of the charger are also on the site.
Hope this helps

Roy

 

old thread now dead.
The OP can always ask a moderator to reopen it.