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How to Test Inverter Board Push Pull Tubes/Circuits

myrkr

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Mar 9, 2020
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I have a dead Bluetti EB150 that I started a thread on and had a discussion around troubleshooting. That led me as far as getting it taken apart and some testing, as well as going back and forth with Maxoak on what to test next. The last place I left off was Maxoak telling me to test the push-pull tubes (sorry, that might not be the correct name due to translation). I've attached a picture here that Maxoak sent me of what to test. I'm not familiar with push-pull circuits and was wondering if anyone had any tips on how to test these with a multimeter to see if they are burned out/shorted.

Here is the full thread if you want more of the details that came before this https://diysolarforum.com/threads/dead-brand-new-bluetti-eb150.12580/

Thanks!
 

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  • Bluetti EB150 Push Pull Tubes.png
    Bluetti EB150 Push Pull Tubes.png
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Vacuum tubes used to be called "valves", and now most equipment uses transistors of one type or another.

Output transistors - using ohms scale of DMM, also diode-check scale (swap leads for both polarities), compare all components of a given part number. Probably two kinds, PNP & NPN or P-channel and N-channel. Three leads, so three possible pairs to measure, 3 ohms readings and 6 diode voltage drop readings per component.

So long as any connected in parallel have resistors in series with the lead before being paralleled, may be possible to get readings from each individually.

Have you applied power, measured to see where voltage is present? Checked temperatures?
My fingers aren't well calibrated, need significant temperature difference. IR imagers are ideal. Cheap IR thermometer can be used to get temperatures. Or a thermocouple (but maybe not when higher frequencies present.)
 
Vacuum tubes used to be called "valves", and now most equipment uses transistors of one type or another.

Output transistors - using ohms scale of DMM, also diode-check scale (swap leads for both polarities), compare all components of a given part number. Probably two kinds, PNP & NPN or P-channel and N-channel. Three leads, so three possible pairs to measure, 3 ohms readings and 6 diode voltage drop readings per component.

So long as any connected in parallel have resistors in series with the lead before being paralleled, may be possible to get readings from each individually.

Have you applied power, measured to see where voltage is present? Checked temperatures?
My fingers aren't well calibrated, need significant temperature difference. IR imagers are ideal. Cheap IR thermometer can be used to get temperatures. Or a thermocouple (but maybe not when higher frequencies present.)

Thanks!

So far I've only been able to measure power at the battery pack of the unit, and at the inverter board, but the unit won't power on and I'm not sure if it's because of a controller issue or something else. All the buttons work when measured, so the signal gets to the board, but that's as far as I've been able to measure so far. Since the unit won't power on I can't measure any temps since it's basically a big dead brick right now. I do have an IR temp gun and thermal camera I can use if I can get the unit to actually power on somehow.
 
It need power to the controller. If not present, see if there is a switcher or linear regulator, and whether voltage is present across the on/off switch or not. Some electronics is always on, checking a pushbutton, and others have mechanical switch to provide power.
 
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