Urgently need a scematic

If you can't get a schematic from the manufacture then it quite likely is simply not available anywhere. Replace the fried components and test the rest of the transistors and diodes with a multimeter, then apply a current limited power source. When I repair inverters I usually run them off either a 3A bench supply or an old computer supply capable of 10A on the 12V line depending on the size of the inverter. That's usually enough to power up one with no load or a small nightlight bulb for testing but not enough to blow up a dozen FET's in the blink of an eye as the hundreds of amps available from a battery will.

I would suggest asking the solar energy people, but it appears that someone has already asked there. Unless, of course, two separate installations in NZ managed to blow up a Trace 2624 at the same time.

If it's one of the square DC fans that are common in computers, you can get a lot of these now that have a tachometer lead that provides pulses when the blade is turning. You'll have to come up with a circuit to monitor the pulses and sound a buzzer (if someone is around to hear it), shut off power (unattended), etc. A simpler way might be a thermostat

in series with a buzzer or relay coil.

How about this... Disconnect the main transformer from everything, and apply line voltage to the output side. Measure the voltages on the windings on the low-voltage side. Replace the burned parts. Measure the resistance of the input terminals (both ways) to see if it's really low... if it is, recheck the repair work. If not, hook a small light bulb (or series string of light bulbs to get the right voltage) to the output of the inverter... where the low-voltage winding of the transformer would usually be. (The bright filament of an 1157

12 V car tail light bulb, or the only filament of an 1156, is about 27 W. Most car headlights are 50 to 60 W.) Then, hook up the battery bank through a relatively small fuse (1 A, 5 A, etc), or use a light bulb instead of a fuse - . In your case you'll put the bulb in the DC input line from the batteries. Give it a try - if the fuse blows, or the bulb in the DC input lead comes on brightly, there's still a problem. If the bulb(s) on the output light up at about the right brightness, you're on the right track. You can either load it up with more bulbs on the output and test again, or go ahead and hook up the transformer.

One flaw in this theory is that I believe some of these inverters have a feedback winding on the transformer to correct the frequency of the oscillator. The light bulb load won't provide this feedback, and the oscillator may not start.

There is a schematic for a very simple inverter here:

One thing I do in cases like this is that if one transistor is blown, and it's not screamingly expensive, I order three of them as replacements. That way, if I was wrong at first, I get two more guesses before I have to sit down and really think about it. :) If I guess right, I have spares for a future failure (if it blew once, it'll blow again) or for some other project.

Good luck!

Matt Roberds

Have you inquired at the solar energy forum sponsored by Northern Arizona Wind and Sun? Several knowledgable people on the forum.

Bill Jeffrey

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snipped-for-privacy@sl> ... for a Trace 2624 inverter (old black box model). Here on Great