20 Most Recent Schumacher 10 Amp Fully Automatic/Manual Charger by Questions & Answers

Go to www.centurytool.net/SE_520MA_Schumacher_battery

Quite simply - the unit has suffered component failure - most likely more than one. Capacitors are the usual source of noisy 'bang' or 'pop' sounds, followed by diodes and bridge rectifiers. If you have some knowledge of electronics, you can attempt repair, but, if none, I suggest leaving possible repairs to someone who does.
The humming sound you hear is the transformer under stress, and, if left connected, it too will die.

I suspect a blown fuse. Read your manual's section on trouble shooting your schumacer to find out if there is one, where it is on the unit and replace the fuse. If it blows again, your unit has probably played up on you.
that would require a specialist to repair it.
you might want to make sure you didn't hook it up backwards, which can damage the machine and sometimes cause a battery to bow up like a small bomb. Dangerous! Exposure to moisture can also cause the unit to fail.
Jim Hart

Soo sorry, unit is DEAD. I’m happy to assist further over the phone at https://www.6ya.com/expert/robert_aad3edb7dfa380b9

Best solution is to use the Auto mode, since the unit will monitor the battery, and automatically switch to trickle charge when the battery is full. In the Auto mode, it won't overcharge the battery.

A battery that might sit for a month at a time, would only need a trickle charge or about 1 amp, a charger of this type can stay hooked to the battery for the whole month. A 10 amp would be for a quick charge or only about 4 - 12 hours depends on how fast the battery lost the charge. A 10 amp charge would cook the battery if left for days.

Since the unit is foreign made, you're going to struggle getting an exact replacement - especially size wise.
I see that Amazon lists the item at under $50, so is it even worth the trouble of searching for one ?
You could always fit a generic replacement, that has a 10A current indication scale, but be prepared to make a minor modification or two to get the replacement meter to fit nicely.
Your local electronics store should be able to assist you in selecting a replacement meter that is closest in size.
Connection is a simple process.

The SE40MAP has an automatic shutoff when battery is fully charged.

Did you try it on a different battery? These automatic chargers won't charge unless they detect a little bit of voltage and not a direct short. Your battery might be shorted out. Good luck, Al K

your car battery has two connections called posts. one is negative and one is positive +. the red clamp from your charger goes to the positive terminal on the battery. the black clamp is supposed to go to ground, like an unpainted bolt but not brake lines or any kind of tube. It can be hooked to the negative or black battery connection as well. just make sure there is plenty of airflow around the battery and you should be fine. I usually do it that way and have never had a problem.. finally set your charger for 10 amps on a 12 volt battery and plug it in.

Chances are the cable with the white stripe is the positive.

However, it would be best to check with a volt meter. Some auto parts stores will check it for you. If you have one or can borrow one and want to check for yourself, set the meter to DC volts (some autorange, some don't). Turn the charger on. Place the leads across the two cables and if the meter is analog, the needle will deflect, usually to the right and show the voltage. If you have it backwards, the needle will move, usually to the left and bounce several times. If it's backwards don't leave the leads connected too long or you might damage the meter.

If the meter is digital and you have connected it correctly, the meter will show a voltage and may have a plus sign in front of the reading. If you connected it backwards, there will be a minus sign in front of the reading.