How to Repair a 12V battery charger?

[dirk pitt]

voltmetre in position AC 20V measure the voltage between the two golden "radiators".
you must have a voltage of the order of 17 or 18V
if not, the transformer is dead (or fuse upstream)
then, voltmetre in position DC 20V measure between points A and B
you must have a tension DC in the same order of magnitude.
If not, the rectifying diodes are dead.
if these two points are OK but still no output voltage. it can be more difficult.

[BobFuck]

Too bad that the resolution of the images is too weak to be able to read the references. Can you post unscaled images somewhere?

It looks like the 2 heatsinks (big "U" in metal) are connected directly to the primary of the transformer. Therefore, measure the voltage between the 2 dissipators with a voltmeter, in "alternating voltage" mode. Attention, the 2 dissipators and the printed circuit must not touch anything of conductor (if not, short circuit), put thick cardboard under the circuit the time to take the measurement ...

Then you can measure the rectified voltage. On this photo :

https://www.econologie.info/share/partag ... U9pCar.JPG

It's on the circuit board between the 2 plots in the lower left corner and the upper left corner.

It looks like the charging current is switched by the mass of 2 big transistors.

A small cleaning (toothbrush and alcohol) would not be too much considering the amount of crap on the circuit ... lets dry well after ...

[chatelot16]

it's real electronics

the rectifying diode are on big radiator, then all the current goes into 2 transistors without radiator ... sad design i would suspect these transistor to overheat

it would be necessary to note the reference of the integrated circuit (or to make a photo well framed above) because with the reference of the transformer one finds the shema which goes around in the doc of the integrated circuit

[plaed]

Hello,
Newly registered I don't know if I'm doing well to revive an old subject comparable to the one that brings me, or if it would have been better to launch a new one (which I can do if necessary).
So I have a very old battery charger (60s?) which no longer works (a priori does not deliver any charging current), and when I open it I have the impression that what seems to me to be a transformer almost liquefied (looks like some kind of paraffin has escaped from it and resolidified next to it).
I try to attach some photos to illustrate.
As it looks of a fairly simple design, I was wondering if it would be possible to repair it for a still reasonable cost, for example if replacing the transformer would be enough (assuming it is indeed the responsible, and where a replacement could be found, given the age of the item).
Thanks in advance for any insights!

outer casing

inside case

front transformer

transformer top

other integrated appearance component

input voltage selector on the right and ammeter on the left

[plaed]

I made a mistake on the last photo, it's the reverse of the output current selector that we see on the right side.

[Macro]

Have you just checked the fuses that are used to vary the voltages and currents...

[izentrop]

Hello,
You already need a multimeter to check all the elements: fuse, transformer, rectifier, galva, contacts of the oxidized wafer...
Then, with that old blunderbuss, if you don't monitor the charge with a multimeter, you're likely to shoot the battery.

[plaed]

Thanks to Macro and Izentrop for your feedback.
Yes I started with the 3 fuses, one seemed to me to be broken and I replaced it with "period" fuse wire, without change.
But at the opening when I saw all this kind of paraffin escaped from the transformer, I suspected that it was the cause of the malfunction.
I have a multimeter, but am a bit like a chicken who found a knife with this in my hands!
Well I know how to identify the fuses and the transformer, but I don't know what the rectifier, the wafer, etc. are, the galva is perhaps what I called the ammeter, or how to check them
But if you want to guide me a little I will try!

[Exnihiloest]

Hello,
Newly registered I don't know if I'm doing well to revive an old subject comparable to the one that brings me, or if it would have been better to launch a new one (which I can do if necessary).
So I have a very old battery charger (60s?) which no longer works (a priori does not deliver any charging current), and when I open it I have the impression that what seems to me to be a transformer almost liquefied (looks like some kind of paraffin has escaped from it and resolidified next to it).
I try to attach some photos to illustrate.
As it looks of a fairly simple design, I was wondering if it would be possible to repair it for a still reasonable cost, for example if replacing the transformer would be enough (assuming it is indeed the responsible, and where a replacement could be found, given the age of the item).
Thanks in advance for any insights!
IMG_0432.jpg
IMG_0433.jpg
IMG_0436.jpg
IMG_0437.jpg
IMG_0435.jpg
IMG_0434.jpg

This stuff is extremely rudimentary. So it must be fixable...

We see that there is no electronics apart from the gray block with fins, which seems to me to be a selenium rectifier, it is the weak link. It must be fired and replaced by a modern diode bridge, like https://www.amazon.fr/SODIAL-redresseur-monophase-KBPC5010-Nouveau/dp/B071PCWZDR/ref=sr_1_5 , to be screwed on the chassis for heat dissipation.
For the rest, if the transformer outputs the alternating voltage to its secondary and all the connections are good, it can only start again.

[plaed]

This stuff is extremely rudimentary. So it must be fixable...

Thank you Exnihiloest, it's a bit the reasoning that I had naively made myself ...!

We see that there is no electronics apart from the gray block with fins, which seems to me to be a selenium rectifier, it is the weak link. It must be fired and replaced by a modern diode bridge, like https://www.amazon.fr/SODIAL-redresseur-monophase-KBPC5010-Nouveau/dp/B071PCWZDR/ref=sr_1_5 , to be screwed on the chassis for heat dissipation.
For the rest, if the transformer outputs the alternating voltage to its secondary and all the connections are good, it can only start again.

Before investing and attacking the replacement of the selenium rectifier, I might have an interest in checking the transformer.
But it would be very useful for me to have some indications on the terminals to be used for the control, and the operating mode (simple connection on the sector to feed, which measurement to carry out, tension or intensity?).
I am attaching a photo of each side of the transformer showing the cables leading from it.
Thanks in advance for your reviews!