Good day
I have a Marshall Kilburn Bluetooth speaker box.
It works perfectly when connected to 220vac,
The problem I have is that it doesn't charge the batteries anymore. With my mult-meter I've tested the output on the pins where the battery pack is connected, with battery pack removed, and found no reading at all. I'm supposed to get a reading of approximately 14.8v dc which is the charging voltage for the battery pack.

I've opened the unit and found a small surface-mounted transformer on the PCB. It has 9 pins that are soldered on to the PCB. On the one side there are 5 pins, and on the other side there are 4 pins.
The name and number on the transformer is:
Camden 13030167

Can anyone please give me guidance on which pins are the secondary and which are the primary pins. And which pins are giving the output for charging the battery pack. I have a feeling it might be the problem on the transformer output.

I'm not an expert, technician or anything in electronics, but I can surely help myself. It's been a hobby of mine for many years and I was able to fix a lot of things over the years. And I'm always willing to learn.
Thank you

 

I could find no data on line for that transformer. I doubt whether it is the cause of the problem. The 220V primary will be connected to the terminals that have the highest resistance between them. The secondary will have considerably less resistance. There may be taps on the windings and there may be more than one secondary winding.
A better trouble shooting approach would be to trace the circuit back from the charging output to find out which components are used.

 

It will be a switch mode psu, can you take pictures of the board.?

 

a small surface-mounted transformer

That's indicative of a high-frequency one, as used in a switch-mode supply, as per post #3.

 

The first thing to do is inspect for a fuse and then check the fuse. Then the next thing is to carefully check the charging connections, because sometimes wires do break or come loose from flexing. And occasionally they become disconnected from the terminals. It is not likely the transformer, if it is a component failure at all.
There may also be a mains voltage select switch that has been adjusted.

 

I could find no data on line for that transformer. I doubt whether it is the cause of the problem. The 220V primary will be connected to the terminals that have the highest resistance between them. The secondary will have considerably less resistance. There may be taps on the windings and there may be more than one secondary winding.
A better trouble shooting approach would be to trace the circuit back from the charging output to find out which components are used.

Thank you for showing interest in my thread, and the feedback I got so far from all you guy's. Much appreciated. I'll take a pic or two of the board and post it shortly. And in the meantime I will take all the advice I got and make work of it, especially by tracing the circuit back from the charging output to find out which components are used, as well as to closely inspecting the connections for possible loose or broken terminals. Will keep you posted of my findings.
Thank you once again

 

Indeed the charger is undoubtedly some sort of switcher power supply, because they cost less to produce than a traditional step-down-and rectifier supply. That is why the transformer is so small and has so many terminals.
Because the rest of the system still operates on the mains power, there is no reason to inspect the mains power connections, and so the focus can be on the battery connection area.
Does the unit operate using battery power, if the battery is not totally dead? Is there a switch that must be operated by inserting the battery before charging can start?? AND, does the battery have more than just the two terminals?? I am still guessing that there is a break some place in the battery connection part of the system.

 

Indeed the charger is undoubtedly some sort of switcher power supply, because they cost less to produce than a traditional step-down-and rectifier supply. That is why the transformer is so small and has so many terminals.
Because the rest of the system still operates on the mains power, there is no reason to inspect the mains power connections, and so the focus can be on the battery connection area.
Does the unit operate using battery power, if the battery is not totally dead? Is there a switch that must be operated by inserting the battery before charging can start?? AND, does the battery have more than just the two terminals?? I am still guessing that there is a break some place in the battery connection part of the system.

The unit operates with either the battery pack or 240v ac. The battery pack consist of 4 x 3.7v Li-on batteries which are connected in series, adding up to 14.8v
When connected to 240v ac, the unit must be switched on in order to charge the batteries.

There's a 4-wired ribbon which runs from the board to a connector where into the plug for the battery pack are plugged into. There are 4 pins on the board where the one end of the ribbon are plugged into. I've checked and tested for any output voltage on these pins, but there's nothing. The first 2 pins (1 & 2) represents positive and the next 2 pins (3 & 4) represents negative.
The batteries are also 100% functioning.
This tells me that the fault has to be on the board, correct?

I'm attaching a few pics of the board and unit.

 

THERE MAY BE A RIBBON CABLE PROBLEM. It may also be that the battery must be in the circuit for the charger to operate. With multiple conductors that is quite likely. two wires for charge and two for sense, and if the right value is not detected then no charge.

 

THERE MAY BE A RIBBON CABLE PROBLEM. It may also be that the battery must be in the circuit for the charger to operate. With multiple conductors that is quite likely. two wires for charge and two for sense, and if the right value is not detected then no charge.

Thank you for your input Bill. I never thought of it this way. I'll conduct some tests and I see if I can detect anything suspicious

 

As MisterBill2 mentions, quite a few battery chargers require a battery to be connected for them to switch ON.