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Schematic for DCB 101 charger


blathim

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Hello,

does anyone have or know where I can download a Schematic for the "DCB101" Charger?

I am an electronic Technician of 45 years newly retired to the Philippines and my dear Friend mistakenly plugged his 110 volt unit into the 220 volt ac here so the schematic would be helpful.

Thank you

Bob

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  • 3 months later...

The best place to start if you don’t have the schematic is to inspect the board. Have you taken the charger apart and checked out the board visually? Can you upload pics?

 

I know you’re an ET but I’ll outline a few troubleshooting tips for the non twidgets on the forum.

 

A battery charger can be a simple or complex device. The chemistry of the battery dictates the charge method and any number of regulating circuitry can be implemented. It is a difficult task troubleshooting a circuit with a schematic, almost impossible to troubleshoot a complex circuit with-out a schematic. However, with a few educated guesses all hope is not lost. You might get lucky and stumble upon the faulty component.

 

We know the failure condition, good news.. kind of.

 

Over-voltage conditions are bad, when 220v is applied to a circuit that was designed for 110v, often the unit is beyond repair. Even if the circuit has built in OV protection, +100v is most-likely out of spec for the protection to save the unit.

 

*I understand the charger may not have all the parts I describe, just trying to be complete. (And I guessing over here)

 

A few things to check, first the oblivious. We hear it all the time, unplug the unit and wait for a while and then plug it back in. This will give caps time to discharge any stored voltage and allow any thermal overloads to rest. Chances are this won’t work, but it doesn’t hurt to try.

 

Next is to try and locate any user resettable breakers/fuses. I don’t suspect the charger has any accessible fuses but again, it doesn’t hurt to check.

 

Next take a look and a smell! Do you see any charred or melted/blackened parts? Does the unit smell like it released that magic blue smoke? Im betting it did.

 

So now with the unit unplugged, let that sucker sit for awhile. Your about to open it up and who knows whats waiting to shock you. Give the unit about 10min to discharge any stored energy.

 

Okay open that shit up. Take a look and try to spot the most oblivious first. You’re looking for exploded components, PCB mounted fuses, and bulging caps. Often a unit like this will have a thermal resistor on the main rail. Most likely its blue and perhaps it exploded. Also check to see that the main transformer did not ‘open’. You should read a resentence with your meter. Another possibility is the unit uses a bridge rectifier, check the BR with the diode setting on your meter and make sure it operates correctly. Next check the MOSFET’s the same way. If it is a switching power supply design, and it most likely is, chances are there will be some kind of automated PWM chip that rides the rail voltage. Over Voltage beyond the chips spec will destroy that guy. Best bet is to get the data sheet for the chip and make sure your seeing what you are supposed to. One pin should have a small voltage (Enable pin), another pin should be the rail (~120v), and a pin outputting a small voltage (Control). It’s a little more complicated than that but not by much. Somewhere on the PCB will be voltage regulators, these guys might be anything from 1.8v/3.3v/5v/12v. You can tell the voltage by checking the part number. Often with an over voltage these parts are damaged.

 

The basic principle of charging a battery states that you must supply a voltage greater than the battery being charged. The charger will have a sensing circuit that cuts off charging when the threshold is reached. This can be a complex design but most likely it some sort of transistor/MOSFET control. Maybe a little precision voltage regulators thrown in for good measure.

 

Bottom line, it’s worth taking a look. Not likely a DIY’er will be able to fix an over voltage but you never know, it really depends on the complexity of the design. If nothing else.. trouble shooting the unit has educational value.

 

It’s a sad world we live in. I wrote a paper in college about how at one point in our history you could find a VCR repair shop on nearly every corner. Unfortunately we have become a “throw away” society, meaning its often times cheaper to buy the newest/latest-greatest product then to have your old appliance repaired. And in your case, the same might be true… but I hope I’m wrong.

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