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Do you think my FET's are good being one set shows 1.889 volts and the other set shows 1.187 from gate to back plate?
Is it possible the driver board is just driving them as hard as it can regardless of what the cpu is asking it to do and I just need a new driver?
Also the only be mosboard I see listed is for a 24v inverter. Are they the same no matter the voltage or are they voltage specific? I'm thinking they're interchangable as the FET's are rated at 40v.
What is the function of the signal board?
Being in Florida humidity gets into everything if it just sits.
Everything and anything. People don't understand that we also get Sahara dust along with that humidity and the two can kill electronics. And there is also salt in the air which adds to the problem.
16 hours ago, Nilao said:Do you think my FET's are good being one set shows 1.889 volts and the other set shows 1.187 from gate to back plate?
Slightly concerning...that's a pretty significant difference for boards that should be completely identical. Depends if the LED is present (and working), number of FETs (and required gate resistors too), etc.
16 hours ago, Nilao said:Is it possible the driver board is just driving them as hard as it can regardless of what the cpu is asking it to do and I just need a new driver?
Technically, the driver board simply converts the 5v 0.02mA (max) SPWM signals from the CPU to ~10-15v 2.5A gate drive signals. Not any smarts there 😉. Unlikely that it's at fault, unless it was connected to FETs that blew--in a PJ inverter, this usually damages the driver board.
16 hours ago, Nilao said:Also the only be mosboard I see listed is for a 24v inverter. Are they the same no matter the voltage or are they voltage specific? I'm thinking they're interchangable as the FET's are rated at 40v.
Voltage specific for 48v anyway--those use 100v FETs. 40v will be fine for 12 / 24v use--not like the amperage is significantly better on the FETs they use for lower voltage anyhow.
16 hours ago, Nilao said:What is the function of the signal board?
The little resistor boards that I pointed out?
The little resistor boards that I pointed out?
No sir, the board that sits to the left of the driver board. If your looking at it from the side the transformer good to the main board.
That board is indeed the "signal board"...it's what converts and scales output voltage (+ charge input, if equipped) and output current to the CPU. If it's not working right, you'd also get a similar result. Output of the "resistor boards" go to this "signal board", and then to the CPU.
The board that's mounted standing upright...has one purpose: to short the SPWM outputs of the CPU out if they feel the need. Not like the CPU has a fault shutdown input that can do exactly the same function...!
Hope no one minds my 2 cents thrown in here;
I would take all the boards including the mainboard out and thoroughly wash and dry them. Lots of soap and water. Then put it back together and see what happens. I see in your pics signs of moisture/dirt getting into several spots, which means its in several spots you can't see as well. As Sid said, by now you may have a damaged lf driver board, even if you have already replaced it once.
13 hours ago, dochubert said:Hope no one minds my 2 cents thrown in here;
I would take all the boards including the mainboard out and thoroughly wash and dry them. Lots of soap and water. Then put it back together and see what happens. I see in your pics signs of moisture/dirt getting into several spots, which means its in several spots you can't see as well. As Sid said, by now you may have a damaged lf driver board, even if you have already replaced it once.
I might disagree on the soap but washing them with distilled water could help.And then making sure they are well dried afterwards. I have been using a boost converter to go from solar panels rated at 18 Volts to get to charging Voltage on the 24V system. I can count on replacing one every 6 months because of the salt, dust, and humidity all attacking the units.
I might disagree on the soap
Dish soap won't hurt electronics but you must rinse it off thoroughly. I have put large electonic boards in the automatic dishwasher and run it thru a cycle with excellent results. In this case the powerjack parts are small and wouldn't remain in place so the dishwasher wouldn't be a great idea. Hand washing with dish soap and a toothbrush probably best. Lots of rinsing and make very sure parts are completely dry before using.
I can count on replacing one every 6 months because of the salt, dust, and humidity all attacking the units.
Wow! Glad I live in Idaho! I bought two powerjacks a few years ago from a guy in Georgia that were badly corroded and with visible rust on the mosboard connections and other places. Had to thoroghly clean them before I could use them, but since being cleaned, have not "re-corroded" here.
My old electric oven can do quite low temperatures so when I have to wash a fouled board that has components likely to trap water (inductors etc) I give it some time in the oven to ensure all the water is gone.
I have had success protecting circuit boards in damp areas by spraying them with a couple of coats of polyurethane. Start with a light mist coat and let it dry. Then lay it on progressively thicker letting it dry in between coats.
If heat dissipation isn't too much of a problem, a NEMA 3 PVC box with a gasketed cover and proper cord grip connectors and silicone works great.
Ok. Sid, I pulled the FETs off the transformer side that were reading 1.143 volts gate to backplate in diode mode. Once I remove them and test them on the bench they test at 1.927 volts gate to drain. The positive FETs test at 1.876 on or off the unit. What could be pulling the voltage down with the board installed?
I actually ultrasonic my boards after doing any repairs and drop them into a tub of rubbing alcohol to remove any water that might be hiding under a chip.
Ok. Sid, I pulled the FETs off the transformer side that were reading 1.143 volts gate to backplate in diode mode. Once I remove them and test them on the bench they test at 1.927 volts gate to drain. The positive FETs test at 1.876 on or off the unit. What could be pulling the voltage down with the board installed?
Umm...have you checked the pinout of the FETs to know what pins are "gate", "source", "drain"?
"Gate" - "Source" should be open circuit both ways on your meter.
"Drain" - "Source" should be open one way (negative to source), and ~0.6v the other way (positive to source).
Most all devices will read considerably different in-circuit than they will out-of-circuit, simply due to the surrounding parts and way they're wired up; that doesn't necessarily indicate fault with the part.