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Power Jack version 7.0 signal board led not lighting, with switch on fan starts when powered on. No output 110v or 220vac.
back light but no display info. Once the unit powers up fan does not turn off when power switch is turned off. You have to remove power to get fan to turn off.
Tried unplugging the blue an black cable from the display board, no change. The power source board also has no led light. Mosfets are fine. Don't have enough info to diagnose this problem please advise of any thing you come up with. Not familiar with this circuit need help. I am an electronics tech but as you know it takes a while to figure out what they where thinking when they designed this unit. Thanks for any help BigBOB
Not sure if this will help, but I remembered watching one of Sean's videos about a similar problem. Maybe this will help:
https://www.youtube.com/watch?v=ur9asnNtKY8
Power Jack version 7.0 signal board led not lighting, with switch on fan starts when powered on. No output 110v or 220vac.
Looks like you've seen the "no power video"...I see that you've tried unplugging the blue/black cable from the LCD board, etc. This gets a bit harder; we will need more info to figure out exactly what's going on.
Obviously the power switch works. And something on the power source board seems to work.
Any repair history on this inverter (blown FETs)? I assume it used to work...what caused it to stop working? (Now's not the time to forget about dropping that 1lb bag of screws into the inverter 🤪. The more info we have about the inverter...even if embarrassing...the better our chances of diagnosing what's wrong.)
Could you provide a photo/short video showing the inverter and how it behaves? Any info is extremely helpful.
Can't say whether the LCD board is at fault here or not; is the backlight coming on all the way, or is it dim?
Power Jack version 7.0 signal board led not lighting, with switch on fan starts when powered on. No output 110v or 220vac.
thanks for the info just finished reversing the L.F Driver for my info. Idon't if you know but there is no 0.1uf capacitor across pins 5 and 8. Thanks i didn't check the output fet's my fault I'll try that next. Again thanks for the feedback. It was given to me as is so i can't say what happened. BigBOB
Does the inverter power on if the LF Driver is unplugged?
There should be a 0.1uF cap across pins 5-8 of both TLP350 chips. Not that this would prevent it from powering up, but damage spreads pretty easily on that little board.
Got some pictures for you, tell me if any are to blurry to see and i will send another ok.
Seems to me that there's more than just a few things wrong with that inverter. Power supply appears to be working.
All of the CPU outputs that I can see are "on" (all 3 LEDs, as well as the LF Driver LED being out). That together with the LCD board being unusable...kinda points to a destructive surge on the 5v rail, blowing out the CPU. How the LCD processor is failing to function (nothing visible) could be a slightly different problem--or similar.
If you measure from the big solder tab on the LM7805 below the CPU board...what voltages do you get on either leg?
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3 hours ago, Big BOB said:Got some pictures for you, tell me if any are to blurry to see and i will send another ok.
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Sid I have +12vdc and 5vdc on those two points
that was from the big solder blob. and again thanks for your help BigBOB
OK, so that part is working perfectly.
At this point, I'm not sure what further to pinpoint. Appears that the CPU is not functioning...and whatever took it out also seems to have taken the LCD out as well. They are not connected (except by the 12v power supply), so that's really weird.
i'll check the crystal to see if it's oscillating next. I have some boards coming so i can figure out which boards are bad. Is the display board a separate processor or does it get its info from the cpu board ?
where can i get a block diagram or flow diagram of what does what. I looked to see what the dc input board does but it doesn't make sense. looks like they are interconnected between the dc and the ac side I don't understand am I looking it wrong. Normally they step up 24vdc to 360vdc then chop that with the power fet's But that doesn't seem to be what they are doing here. Unless i missed something. Please advise. Thanks BigBOB
i'll check the crystal to see if it's oscillating next. I have some boards coming so i can figure out which boards are bad. Is the display board a separate processor or does it get its info from the cpu board ?
It won't be oscillating. Gotta love PJ...they have a crystal soldered to the CPU, but the CPU is running on it's own internal oscillator. You could rip the crystal off the board and it wouldn't make any difference.
where can i get a block diagram or flow diagram of what does what. I looked to see what the dc input board does but it doesn't make sense. looks like they are interconnected between the dc and the ac side I don't understand am I looking it wrong. Normally they step up 24vdc to 360vdc then chop that with the power fet's But that doesn't seem to be what they are doing here. Unless i missed something. Please advise. Thanks BigBOB
This would be the case for a HF (high-frequency) inverter. These Power Jack inverters are LF (low-frequency) inverters...all of the switching is done at battery voltage.
Mainboard is nothing more than a FET H-bridge.
Is the display board a separate processor or does it get its info from the cpu board ?
LCD board has a separate processor...there is no connection to the CPU board. It just gets voltage/current feedback from completely separate sensors.
If I had to take a stab in the dark at diagnosing fault, it seems the CPU is faulty. If I recall correctly, there's no place in the code where it holds all 3 lights on.
The only thing that could blow the CPU would be the FETs through the LF Driver. In a PJ inverter, if the FETs are blown, the LF Driver 99 times out of 100 is also blown. Without testing the FETs, we can guess they're good...but not so sure about the LF Driver.
LCD board also appears faulty, as it's lighting up, but not displaying anything. (A similar failure mode would do the same thing: processor is holding everything high.) You could try adjusting the little potentiometer on the LCD board above the LCD (should be LCD contrast)--see if that helps at all?