Battery charger/starter repair

Sure, get in there with a meter and probe around. Check that you still have AC on the secondary of the transformer for a start (since it's humming, I assume you have 120v AC the the primary), and work forward from there. Rectifiers are easy to check with any multimeter. If they're dead, replace 'em. There's not much stuff inside a cheap battery charger...should be pretty simple.

Read the Repairfaqs for safety precautions.

jak

jakdedert wrote in news:OLUxf.32849$_ snipped-for-privacy@bignews1.bellsouth.net:

OK jak, i took some readings

The transformer is good. Mode 2 AMP auto charge >>> 23 V AC

Mode 10 AMP auto charge >>> 27.6 V AC

Mode START ASSIST >>> 30 V AC

At the battery leads the output is 0 V for 2 and 10 AMP Auto Charge.

It is 13 V DC in "Start Assist" mode.

Power off resistance readings at the battery clips indicates Infinity with thw START/CHARGE switch in CHARGE mode.

I read 472 ohms with the START/CHARGE switch in "START ASSIST" mode.

I get a hefty arc when I slap the leads together in the shortest time possible in START ASSIST mode.

Apparently my regulated auto charge in 2 and 10 AMPS is burnt out.

If I attempt to charge a battery in the START ASSIST mode I will probably blow up the battery and the charger and set fire to the world.

It is only a 55 ampere rating for the start assist.

Since this is a fern (red chinese) battery charger, I may be ahead of the game to throw the dern thang in the garbage and buy a nice AMERICAN MAID bat-tree charger/start assist that I can get schematics and parts for.

Do you or anyone else know of or recommend a good direct jump (100 amps ?) battery charge starter, that I can get parts and scats for ???

thanks

Dave :">

So there's a diode or diode bridge in there that works. Good.

So, either a different rectifier (or bridge rectifier), or a circuit breaker, or a current limiting resistor is toast. Check any diodes with the resistance scale (or diode symbol if it has one) on your meter. IF you get a reading in one direction, reverse the leads. The reading should be much higher with the leads reversed.

Regulation, such as it is, is usually just a resistor in series with the DC output. I'm leaning towards the proposition that a fairly hefty resistor in there is open. Look for a high-wattage resistor connected to the switch.

Don' wanna do that....

Good luck finding one.

Ebay...or AutoZone...other auto store. Most likely anything you find will be made in China, unless it's pretty expensive. Then, you'll be unlikely to 'need' the schematic.

jak

Thanks jak, I will perform more surgery on this electronic victim by ripping its guts out later.

Good suggestions.

Apparently an active regulator and a circuit board.

Separate start and charge circuits. Transformer common.

(I can still use the dern thang to jump start, just not trickle charge)

dave :">

I'd check it out some more. There's a common enough Thyrister / "Silicon Controlled Rectifier" circuit in use for many battery chargers. It is simple, inexpensive and works very well. With no voltage out and the boost output drawing high current, it suggests the diodes are OK. The SCR or triggering circuit may be dead.

Find the part number on the SCR (assuming that's what they use). Look up the terminals on line if possible. If you can't find a number, no big deal. The anode side goes to the positive output of the rectifiers, the cathode goes to the positive lead, the gate to the circuitry. "as a rule" - but not carved in stone. Anode and Cathode will be heavy wire.

The SCR could be a three lead component that is just pressed into a heat sink - similar to the diodes used in auto alternators. It may use the case for one of the connections or have three separate leads.

You can test the SCR easily. When the gate is made positive with respect to the cathode it should conduct. Disconnect the control circuit from the gate. Connect a 9 volt battery in series with a 200 ohm resistor. Minus of the battery goes to cathode (output lead) and plus (resistor) goes to the gate. While connected - you should have output on the charge leads. It may be lower than you'd expect for a

12 V battery, but that's normal. Connected to a battery it should bring the voltage up (don't leave it on long - just to test)

Beyond that (SCR checks good) it takes more effort - but it isn't particularly difficult to fix since the regulator control circuits are usually quite simple - a dozen or two of parts to check, and easy enough to draw the schematic from the board.

Then it is a matter of deciding how you'd rather spend your time - earning the money to replace it or learning to fix it.

Draw the schematic, scan and post it on alt.binaries.schematics.electronic and you'll have people falling over themselves telling you how to check and fix it.

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default wrote in news: snipped-for-privacy@4ax.com:

Thanks for all of your help.

You are a genius.

Do you work on alien technology also ?

dave

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JR North wrote in news:icWdnXnQpJ_Y31TenZ2dnUVZ snipped-for-privacy@seanet.com:

Thanks for the info!

I suppose that I really do not need 100 amps to jump crank a nominal earth made common mode terrestrial vehicle of mass production used by surface dwelling humanoids.

:'>

dave

JR North wrote in news:icWdnXnQpJ_Y31TenZ2dnUVZ snipped-for-privacy@seanet.com:

Be a pal hal mal.