I blew it(Johnson A419) Now lets fix it!! w/pics

Like many before me I purchased a Johnson A419 24v and tried to juice it up with 120V. After the smoked cleared I opened it up to see that two resistors were blown ans possibly a capacitor (circled). Assuming all the other components still work I should be able to clean it up and solder in the new components.
The problem is that I dont know what size resistor or capacitor to replace the bad ones with as they lost their stripes when they went up in flames.

So if anyone has a Johnson A419 24V model please post a pic of the circled components (two resistors and the capacitor) and ill keep you posted on the repair.

Where is everyone? I usually get a response in a hour.

Sorry, mine are both 120VAC, so there's a transformer mounted there instead of resistors.

Do you think its possible to replace those resistors with a transformer to run the controller? I would be converting a 24v to a 120v. I would also have to step up the relay.

DOA you let the smoke out.

You have no idea how much of the circuitry you zapped. Get a new one and start over.

Sawdustguy said:

You have no idea how much of the circuitry you zapped. Get a new one and start over.

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It was ONLY 5X the rated voltage....

Seriously, you have not idea what the voltage did before those components gave up their magic smoke.

More than likely, the circuit board has also been fried. There's little hope for resuscitation. RIP controller.

Looks like those resistors are on top of a transformer footprint. You could drop a 24V transformer on there and use it with 120V.

Or, replace those resistors with wire jumpers. That "cap" was probably a 24V varistor, and definitely got toasted. For a test, you could just leave it out - not necessary for normal operation - it's meant to protect the ckts agains overvoltages - but what's the chances of that happening!

I'd take a shot at replacing those resistors with wires. If it works, great. If not, very little time and not expense lost.

passedpawn said:

Looks like those resistors are on top of a transformer footprint. You could drop a 24V transformer on there and use it with 120V.

Or, replace those resistors with wire jumpers. That "cap" was probably a 24V varistor, and definitely got toasted. For a test, you could just leave it out - not necessary for normal operation - it's meant to protect the ckts agains overvoltages - but what's the chances of that happening!

I'd take a shot at replacing those resistors with wires. If it works, great. If not, very little time and not expense lost.

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One way to confirm this would be to see what the output of the transformer on the 120V model is.

Anyone want to take a peek inside their 120v A419 and read to us what the output on the transformer is. Please?

JewBrew said:

One way to confirm this would be to see what the output of the transformer on the 120V model is.

Anyone want to take a peek inside their 120v A419 and read to us what the output on the transformer is. Please?

Click to expand...

probably 24VAC (rms). I see a group of diodes there for rectification. Anyway, since your unit already takes 24VDC, you could definately use a 24V transformer.

I'd bet if you peel that sticker off that zettler relay you'll see that it is a 24V coil type.

Just put the jumpers across the resistors and fire it up with 24V (dc or ac I'd guess would be OK).