Maxstar 140 - Failed Drop Test

I have some experience with dropped computers. You don't need a schematic.

If it fell, the damage is mechanical. Give the machine a good shake. Listen for any rattles.

If it rattles, take it apart and see what is causing the rattle. If something was jarred loose, plug it together again. If something is visibly broken, replace the broken part.

If it does not rattle, you most likely have a cracked printed circuit board. Hairline cracks are not visible to the naked eye. Take the machine in for repair.

look for any cracked boards inside, etc. are there any fuses inside? check them.

Rarely I can see a three liner post that is as helpful. That would be my suggestion as well. Just poking with a multimeter will likely get the OP to the answer.

i

Thanks all.

I had already disassembled the unit, including removal of the heatsink. With a large weight, I would think this would be the area of the board to be damaged. No luck with any visible damage.

I have probed the power so far, but I am not sure how the autolink circuit functions. If it was straight power to the rectifiers, no sweat. But I am assuming that there must be some sort of detection circuit / switch over for the 115 / 230 operation? Without a schematic for this section, it is getting a little confusing keeping track of the flow.

Regards,

Steve

Check out page 22 of your manual

there is a schematic there. Go from it. Incoming wires should go into an input choke. Maybe it will look like a transformer connected to capacitors. See if there is voltage coming into and out of the choke.

Then there is a rectifier bridge, probably mounted on a heatsink. See if there is AC power coming in and DC coming out.

Use this schematic as a checklist.

See where the main switch is connected and whether it properly tells this maxstar to turn on. Etc etc.

Post your findings on an organized fashion, maybe take digital pictures and post them also. It would be hard to imagine that you cannot figure out just which part is broken.

i

Check the solder joints. A "cold solder" joint could have broken. It's a vary common problem in many electronics products.

Bob

THe autolink's output should be to a DC buss sitting somewhere near but above the welding Open circuit voltage

the buss should feed to Honkin big transistor type "thingies" (For the electronics people like me I'd ahve called them IGBT's or something in the FET family Mostfet or similar)

The autolink powers up the BUSS and the big transistor thingies control the current going into the welding and then the boards mainly control te large transsistor output.

Basically the block diagram of an inverter welder is the same as a motor controller at a high level and an AC/DC inverter welder is the same as a variable frequency drive

But that could be oversimplification

here is an easier question

IS IT IN WARRANTY?

If so take it in

snipped-for-privacy@netscape.net wrote:

Thanks Brent,

IGBT's or FET's are fine by me. A previous life had me designing inverters (low power sonar) and recievers. Concept is the same, this is just a lot more sophisticated.

So far I know there is no power to the rectifier or the four large electroytic capacitors. Would a failure associated with the Autolink prevent power going to the rectifier? There is a 30A relay in the power side (so far haven't determined it's actual function) that I originally thought was part of the Autolink circuit, but now I am not so sure.

Am I to assume that the Autolink has nothing to do with the incoming voltage, but rather adjusts the welder output based on the power input?

No, the welder is not in warranty.

Regards,

Steve

Looks like the schematic depicted MOSFETS.

I doubt that they would repair a drop damage for free. And with all kinds of professionals, it is good to figure out what is broken and not let them tell us what they think needs to be repaired.

i

Just getting caught up with the news. I used to fix a lot of electronics, one trick is the get a can of that Freeze Spray. Spray it on sections of the circuit board. (The copper side) The good stuff basically makes a frost form on the board and hairline cracks will show up.

Jerry