Lestronic II repair attempt

[coosa]

>>>Connect the two wires from the transform back to the fuse terminals, but not to the diodes.

Bypass the relay on the control board, or if the cart is handy, plug into cart. Just so the transformer hums when plugged into AC power.

Measure the VAC between the two wires that were originally connected to the diodes.<<<

The charger is now sitting on a bench beside the cart, so I reconnected the fuse terminals and plugged in both the AC and DC. I set the meter on AC and tested the wall receptacle to make sure the meter worked right on that setting - it showed 122 volts, so it must be ok. It gave a reading of 3.42 across the 2 wires that connect to the diodes. It didn't matter which lead I used for the + and -; it read 3.42 each way.

I'm starting to suspect that I have a transformer problem and this thing is headed for the junk pile.

Thanks!

[JohnnieB]

I should have suggested checking the transformer sooner.

[coosa]

Originally Posted by JohnnieB

I should have suggested checking the transformer sooner.

So does the 3 volt reading confirm that it's dead?

It was worth a try to fix it, and thanks again for all the help. Maybe we are at least leaving a good thread for folks to search in the future.

[JohnnieB]

Originally Posted by coosa

So does the 3 volt reading confirm that it's dead?

It was worth a try to fix it, and thanks again for all the help. Maybe we are at least leaving a good thread for folks to search in the future.

Not quite, but pretty close to it.

I've just never seen a transformer with two secondary windings that are tied together to form a single center-tapped secondary have continuity on both secondaries and no short between them not have close to their rated voltage out, or smoke leaking out, or bad meter being used or misused.

You measured 122VAC of the wall outlet, so the meter is okay and set to the VAC scale, so the 3VAC meassurement is likely to be a valid one. The power cord gets warm (hot?) meaning quite a few amps are being drawn by the primary windings, so the secondaries are drawing some amps that are going somewhere other than to the diodes, but not bad enough to smoke.

Like I said never, seen anything quite like it before, but I'll believe most anything can happen in electronics, I've seen some doozies.

Bottom line. You need another charger.

[coosa]

Thanks again, Johnnie. I actually have 2 of the EZGO 36 volt chargers that are strictly for this cart, but they are not as quick as the old Lester was. I hate to see it declared dead, but it happens to everything of this world eventually.

It does have quite a few parts I can salvage off it. If anyone needs that 40 amp fuse, let me know.

[Sergio]

coosa, I did not see where you tried what JohnnieB suggested earlier, testing the voltage output with the capacitor disconnected.

It is possible that the capacitor is so off that the LC tuning circuit is saturating the transformer core at a very low voltage.

[coosa]

Originally Posted by Sergio

coosa, I did not see where you tried what JohnnieB suggested earlier, testing the voltage output with the capacitor disconnected.

It is possible that the capacitor is so off that the LC tuning circuit is saturating the transformer core at a very low voltage.

No, I didn't test it that way. I'll give it a try. Thanks!

[JohnnieB]

Originally Posted by Sergio

coosa, I did not see where you tried what JohnnieB suggested earlier, testing the voltage output with the capacitor disconnected.

It is possible that the capacitor is so off that the LC tuning circuit is saturating the transformer core at a very low voltage.

The fact it wasn't tried without the capacitor, blew right by what few working brain cells I have left.

Thanks for catching that Sergio.

[coosa]

Got back to testing it this afternoon. First, I used the meter to remove all the stored power from the capacitor. With it set to DC voltage, it started out at 75 volts and over the next 30 seconds steadily dropped to zero. That was a surprise. When I did it yesterday, it only started at 3 or 4 volts. No idea why there is such a difference. I shorted across it with a screwdriver and confirmed there was no power left in it, then took both clips off.

Then I plugged in both the AC and DC cords and took a reading at the wires that were supposed to be on the diodes, using the AC setting on the meter. The reading I got then was 59.7.

So what does that tell us? I am just the helper getting the red wrench at this point. :)

[Sergio]

That means you should listen (read) closely to what JohnnieB says

It looks like you just need a new capacitor and you should be good to go.

Make sure you get a capacitor with the proper voltage rating, typical run capacitors for HVAC are either 370v or 440v and you should get one rated for 660V.

The output voltage without the resonant capacitor installed should be between 55v and 65v