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No brand/5500W inverter disaster porn
Pete:
Sorry the second post was by Noneya.
I have removed the caps, will take the plunge later and see how it all goes then.
I realised that it appears the main board is fed battery power from the Fet/Heatsink board so my original plan would not have worked.
Did not mean to hijack the thread, it seemed that you folks have a lot of experience with these things.
Pete
lighthunter:
yeah, noneya's way may be easier what could be tricky is if you have one or more wounded fets, it will distort the wave shape. Thats still a win because youve found a problem but you dont know its your driver or a fet. If you have removable fet boards that might be easy to separate though.
I dont remember if PJ is unipolar or bipolar in other words, bipolar is switching all 4 fet banks at 24ish khz, unipolar is switching two banks at 60hz and the other two at 24khz. I thought the pj control boards ive worked on were bipolar.
So heres an example of a unipolar 8010 gate drive
First a photo of a 60hz gate drive then a photo of a 24khz drive
showing the pwm 60 hz component, then a photo of the 24 khz pulses. All you are really looking for is the full 12v drive strength and fairly straight square transitions.
Pete:
Thanks Lighthunter, I used Noneya's method, took out the large caps and put a resistor in series.
I had already changed all the AC Mosfets over, i used Hy4008 mosfets. I also changed all the 47 ohm resistors on the mosfet board as well. Surface mount stuff sure is fiddly but I managed it in the end.
So firing it up all looked good until it screamed at me, No caps so no big bang. I checked the output ( pin6) of the optocouplers and it was rubbish. So delved a bit deeper and changed the 4 surface mount transistors on the driver board.
Then checked and found that there was a short still on two transistors from emitter to collector.
I pulled the TLP 350 opto couplers out of their sockets and the short went.
I have some on order so will have to wait until they arrive to go further.
I did order one of those inverter boards you talk about in the article and will play with it when it arrives. As long as we are not being punished too much for our politicians big mouths.
Thankyou both you saved me a stack of fets and lots of work
Pete
noneyabussiness:
Good to here that helped, not my idea, I was suggested it by Oztules years ago when I was playing with em... the PJ 's are bipolar, I would check the low side driver totem pole transistors.. by memory " MY " and " NY " surface mount ...( nevermind you already did )
The PJ's are tough, but can be fiddly... why I changed to the Eg 8010 boards... simple and VERY tough
Pete:
Hi Noneya, yes I have changed the NY and MY transistors. I am keen to try the inverter module when it arrives. This powerjack has two transformers in it. As their 8000 watt rating is so far over the top I am toying with pulling one of the transformers out and using it as a test bed for the 8010 inverter board.
Haven't seen any posts by Oztules for quite a while, I wondered what happened to him.
thanks again.
Pete
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