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Russell H.
Russell H., Service Technician
Category: Electrical
Satisfied Customers: 11201
Experience:  Educated decades ago in electrical quantities and devices, I have practiced professionally in the field ever since.
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Schumacher Fully Automatic Battery Charger - Model CS-810A.

Customer Question

Schumacher Fully Automatic Battery Charger - Model CS-810A. The unit was brought to me because it quit working. Its an 8 bank unit. One half went out, then the second half went out. When the unit is plugged in, the transformers are humming and the side fan is running. All the side fuses are in tact and cleaned. I noticed some of the circuit boards, the ground solder joints that connects to the heat sink were burnt and broken. First I wanna make sure the transformers is outputting the proper voltages. There are three transformers. 2 big transformers that are multiple outputs and 1 small transformer that runs directly to the circuit boards. I am getting voltage readings from them but not sure what the proper value would be. The only information I can get on the 2 big transformers is H420-04 then this appears underneath it 1039SF1 then 10/00. Not sure if this the model number or not. Then next step would be to make sure SCRs are good.
Submitted: 2 years ago.
Category: Electrical
Expert:  Russell H. replied 2 years ago.
Hi, thank you for contacting My name is Russell. I will do my best to provide the right answer to your question.

The heat sink may have overheated, by the sound of it.

That hints that current limiting or voltage regulation may have gone out of specs.

As for transformers... by nature, they can undervoltage, but cannot overvoltage (passing a minor miracle).

So aside from the SCRs, I advise you to consider whatever does voltage regulation and limiting. A shorted SCR might foul that up, for sure.
Customer: replied 2 years ago.
Hi Russell, Thanks for replying. I did a voltage test on the smaller transformer that connects directly to the pcb boards. Its a single primary transformer with center tap and dual secondary. One side I get Primary 120vac input and center tap to end post I get 8vac output, then center tap to there end post I get 8vac outpout and when I test end to end I get 13vac output. Now on the other side where the other secondary winding is I get 8vac output from center tap to end post, then 8vac from center tap to other end post and from end post to the other end post I get 16vac. Not sure which one would be correct. I did change out the 2 SCRs on one board. I working one board at a time. What about the bigger transformers. I get 120VAC coming in, but again, I have dual secondary. One side of the secondary each terminal has two leads coming off. One lead goes to the red wire on the battery clamp and the other wire goes to the fuse box mounted on the side of the box. Now on the other side of the transformer where the other secondary windings are, both leads go directly to the PCB board where it taps into the SCRs trace. Again, not sure what voltage readings I should get on either secondary side.
Expert:  Russell H. replied 2 years ago.
If in one secondary winding, you get 8 VAC to either side, from the center tap,and you get 16 VAC across the whole secondary... ...and on the other, you get the same 8 VAC from the center tap to either side,but you get 13 VAC across the whole of that secondary winding... then the second one either has something wrong in the transformer, or something shorted leading from that secondary, I would think.Double-check that, I advise.