Arlec Battery Charger Model ps470 6volt & 12volt DC

[Walter Graham Robinson]

I need help with an Arlec battery charger. It blew the Main Capacitor and it did such a good job of it that it was difficult to read the specs. What I could make out was the number 0.22uF I think. The cap also was piggybacked in other words there was 2 of them engineered to be 1. and was polarised. The battery charger has 2 x switches. The first has 3 x selections: Off, 6 x Volt, & 12 x Volt. The second switch also has 3 x selections: Minimum, Medium, and Maximum [Engine Start]. Now I replaced the cap with 2 x piggybacked 0.22uF 16v caps with the negative side of the cap joining the positive wire. When I turned the charger on to the 12 x volt selector it gave me a reading of 12.6 volts DC on the Minimum selector 14.0 volts DC on the Medium selector and 15.8 volts DC on the Maximum [Engine Start] selector. Unfortunately, the Amp Gauge never moved off zero. Even with the multimeter showing good voltage. When I moved the first selector switch back to the 6 x Volts position the caps blew up with a loud bang.

My questions are 1) Do I have the polarity the right way round? 2) Why doesn't the charger register any amps on the amp gauge when I've got it connected to a discharged battery and the selector switch in the 12 x volt position? 3) Do I have the correct value cap? 4) What would happen if I increased the size of the cap? 4)Would increasing the size of the cap give a current reading on the Amp Gauge? 5) What do you suggest would be the right-sized Cap to put in? Bearing in mind that the original Cap was virtually destroyed so it's hard for me to read the value. I'm only guessing that it's 0.22uF with two of them piggybacked.

Thanks in advance to anyone who has the intelligence and knowledge to answer my questions. It's a good robust battery charger and everything on it works fine except without the Cap there is no voltage reading whatsoever. Please help..!?
Walter Graham Robinson is online now Report Post

[redwire]

Re: Arlec Battery Charger Model ps470 6volt & 12volt DC

I can't find that model number. Can you post clear pictures of the circuit board to figure it out. It's 2.5A?
Two things are unusual- it's a small value cap 0.22uF 16V and they must have had a design problem to piggyback two parts. I would think 22uF is more typical part size for an electrolytic cap, and usually a 50V part of the SMPS IC section.

The charger might have really weak output so although you measure 14.0V it might be collapsing when connected to a battery and that is why the ammeter reads zero. Or it has an output relay/switch that is disconnecting it or something.

[Walter Graham Robinson]

Re: Arlec Battery Charger Model ps470 6volt & 12volt DC

Thanks for your answer and avid attention to my problem. I worked on it again this morning and unfortunately blew 2 x caps. Quite loud and frightening. Then I realized that I was dealing with the 240volt AC pre-transformer. I thought I was dealing with the 12volt DC side. I have no idea what would be the best-sized cap to go in now. I'll check the model number and take a photo tomorrow and get back to you. Once again thank you for caring.

[Walter Graham Robinson]

Re: Arlec Battery Charger Model ps470 6volt & 12volt DC

Hi Red, I've managed to organize 3 x PDF's showing photos with relevant information. I'll take further photos today showing the wires running into the transformer. I'll make sure the photos are clear and informative. Once again thanks for your learned help. It was a very good Battery Charger and I'd like to get it going again. With your help, I'm sure I'll achieve a good end result.

[Walter Graham Robinson]

Re: Arlec Battery Charger Model ps470 6volt & 12volt DC

Hi Red, will these photos be any help?

[eccerr0r]

Re: Arlec Battery Charger Model ps470 6volt & 12volt DC

wow... can't make heads or tails out of the photos... Maybe zoom out a bit to get a full view of what's in it and how it's connected, where the line comes in, battery leads out, etc.?

Those white things with lots of F2 terminals on them, are they epoxy encapsulated modules? Diode packs?

Seems like a fairly rudimentary, *huge* line frequency transformer based charger, or is it? Small 2.2uF capacitors usually have no effect on these types of chargers.

[redwire]

Re: Arlec Battery Charger Model ps470 6volt & 12volt DC

It looks like the on/off/6V/12V white block is a rotary switch, like something used in big appliances here. It seems to do a tap change on the transformer primary and my guess is the blown cap would be to lessen arcing of the switch contacts. The charger would work with it missing- but do not change the switch while it is plugged in or running, for test purposes. The switch would arc without the cap(s) if you changed on/off/6V/12V with mains connected.

The cap might have originally been two piggybacked 0.22uF X2 275VAC boxed film caps. If you put in only a 16V electrolytic cap it would blow up because there is mains AC potential across it.
It's a bit large value, I would think 0.1-0.22uF is enough.

I would put in one 0.47uF X2 275VAC or 305VAC film cap something like Epcos B32933B3474K000 or use two 0.22uF Epcos B32932A3224K000
I don't really know the suppliers in Australia, RS is an example but they always want you to buy a bag of them.

Careful the (new) cap can bite if it gets any stray charge on it, usually a 1MEG 1/2W resistor is across the cap to prevent this. I'm saying if you unplug the charger when it was on, the power cord could nip if you touched the end prongs and the cap discharges into you.

If you're saying the charger no longer works right then a power surge/lightning might have caused other parts to get damaged.

[Walter Graham Robinson]

Re: Arlec Battery Charger Model ps470 6volt & 12volt DC

Hi Red, good news I solved it today I put in a 250v 0.22UF cap and it fixed the problem. The battery charger works like brand new. Thanks for your suggestion. You were right, bit of a brainiac you are. Thanks, Thanks Thanks. and God Bless. Have included finishing photos for your information.