Repco NS-12V16A charger repair log

[tautech]

Arrived dead as a dodo bird !
No lights, buzz or anything.

Teardown time. 
Both end caps are retained with Torx screws into slots in the extruded Ali enclosure and caps retain both the slide on lid and limit PCB movement.
PCB slides into a slot in the extrusion and is otherwise unrestrained except for the end caps and 3 clamps that fasten the 5 power silicon devices onto thermal pads to the enclosure for it to act as their heatsink.

Inspection of the PCB immediately disclosed a very neatly ruptured 4.7 uF 400V cap that serves as local bulk capacitance for the primary side supply of the control circuitry SMPS. Further investigation found no further faulty componentry in the control PSU however the ~325 VDC it's supplied with from the main bridge must pass through a small inductor which had decided to change its primary function and become a fuse ! 

So yes, this charger has 2 SMPS, one for the 12V 16A charge capability and another sourcing current from the same rectified mains supply to supply the control circuitry.
The larger charging SMPS is controlled by the very popular DIP8 TL3845 Current-Mode PWM Controller and the control circuitry a DIP7 FSQ510 with an integral FET.
Datasheets:
https://www.ti.com/lit/ds/symlink/tl3845.pdf?ts=1599464246567&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTL3845
https://www.mouser.com/datasheet/2/149/FSQ510-85947.pdf

After a rat around through component stashes a 10 uF 400V cap was subbed for the original 4.7 uF and a leaded inductor of similar value subbed in for the one that thought it was a fuse.

Power ON tests were without a load except for for the draw of the control circuitry so a dim bulb tester was employed to prevent magic smoke escaping. 
No pops, flashes or noise.....only lights....the right ones too ! 

As our esteemed leader would say: winner winner, chicken dinner !
Some real burn in/out tests await tomorrow on 200AH truck batteries. 

Some pics to finish, the offending components resting their last days on old needle nose pliers.
The replaced inductor in bright green is below the heatsink of the bridge rectifier and the pliers point in the general direction of the larger cap replaced near the PCB #.



Some pretty lights and a voltage on the Fluke indicating charge ! 

[mnementh]

That battery charger is entirely too smart for the likes of me. I'm still using a 13.8V/6A bump-in-a-wire power pack off a LV lighting kit to overnight-charge any dead car or SLA battery I run across. Works a treat.

mnem
 

[tautech]

Repaired charger had a beating today charging numerous heavy equipment batteries ...... passed with flying colors ! 
So back to its owner it goes.....along with a repair bill !