i miss the 4g ee 1800Mhz videos band 3 and band 20 videos i'm in northern ireland and on the same boat as you i'm started back in september playing with 3 in my area with panel and lpda antennas, i'm trying ee on a pay as you go sim, I would love to see how your getting on at your new house.
I evolved from using the antennas in the end. the new place is in a real bad signal blackspot so i found a second hand mikrotik 4g dish antenna which is working wonders. Ill make a vid!
The logic of replacing mosfets in groups, as mentioned below is that, where the design shares the load across parallel groups of fets, you want very similar performance specs, particularly in relation to turn on/off times. Apart from testing all components and selective matching, the next best approach is to buy a bunch at the same time and hope they are all from the same manufacturing batch. In this case - since the design seems to use 5x parallel dc to dc converters - I would remove the fuses and 4x fets from the one that had blown two fets and try to move forward from there. Might be able to get it running at a slightly lower power level ???
Started using one of these yesterday. Already not working after using 2400 watts of water pump. Their manual says to use an inverter 3-4x the power requirements of pumps and inductive motors. I thought thats what the 8000 peak power rating was for.
wow some of the replys on here, i fix electronics for aliving, over 30+ years in my experiance, replace all mosfets not just a few, as u can bet your arse, that it would have weakened the rest, dc side falis 90% of the time, but also ac side fets can also be under presure, if u want a reliable inverter, get mosfet numbers, and get higher value amp ones wih voltages higher also, make shure switching speed in ns is same nano seconds responce to switch if not can cause heat switching faster or slower than what circuit is built to run, ive found beefy transistors or ibgt work beter when replacing fets, convert more money but makes inverter last alot lot longer,
Bought one a few years ago, it blew at 70% load doing the morning coffee. DC side pair failed. On checking FETs had right digits but wrong letters, factory had swapped suppliers for a different FET brand, right volts, right amps, but lower max watts, guess they had a lot of failures. Got a refund and told to bin it, so correct FETs preferred with the refund...5 years on still going....
if you have a two-channel oscilloscope, try measuring the gates of the mosfets of one of the transformers with a probe and see the dead time, it seems to me that this is the whole problem, two transistors opened at the same time and the result is that all input mosfets are destroyed
fixed it yet? maybe sell it for parts as is i also have a Lvyuan like that, but smaller, that only worked 6 months,then it let the smoke came out of it; heck i would give you 60 euros/dollars for it,i need 3 transformers for my 1500/3000W , it oveheated,or i'll sell it for 20 bucks
I would remove all the mosfets and trace each gate pin hole back to the driver, could be driver death. No good just putting in new parts untill you know if the drive circuits are ok. Just my opinion.
I one time face this issue with my 1000w modified sine wave. I am not a mechanic but I did an experiment, I replace all dc side MOSFETs and their gate SMD resistor. I also replace ac side FETs. my unit starts. this happens when something is shortcircuited at the load side. I am currently using lvyuan 1000-watt unit. I only use it on 500 watts continuous and it is running smoothly so far. I uploaded its videos on my channel.
cool, ill have a look! yeah make sure you monitor the temperatures. im pretty sure the excessive heat is what killed my unit. my replacement fires up the fans as soon as a moderate load is applied which is comforting
Interestomg. I have been looking at videos with load tests for this exact make and model inverter to see how well made they are. if you just poke your meter to the DIODE setting, you can probably test the mosfets "in situ". it is possible all are dead - but either way I am wondering if the fault is what DRIVES them. Usually, I am guessing they want to zip along, switching at several tens of kilohertz to drive the transformers. If however the drive has failed and left either (or worse, BOTH) sides of the bridge powered and not oscillating, the this would give a dead short situation. Perhaps go walkabout with your meter on the DiODE setting and see if the mosfets are dead. if they are ok, then with all fuses for transformers out, does the board still power up the drive electronics? if so, can you see if you have a switching signal going to the MOSFETS? Even if you do not have a scope, some meters these days have a frequency counter built in - and if you see the drive pins clocking away at a few tens (possibly hundreds) of kilohertz, then it would seem that the drive circuit is ok. If the gates of the MOSFETS are being turned hard ON and not oscillating, then it seems like it might be the drive electronics. As it was just TWO MOSFETS that you think may have died, are these two of several on the DC side - or were they the high voltage MOSFETS? If not sure, what is the part number - if they are rates for under 100v, then they are the dC input side, if they are 400v / 600v rating, then i guess they are the AC side (which would seem unlikely). Meter on DiODE setting would be my first suggestion. Can you see 0.7 on each junction or 0.0 short ?
hmm, thank you very much for you help, ill look into it a bit more based on your advice. i will have a check with my mulitmeter and get the scope out. im lucky enough to have a micsig to hand so we may be able to get to the bottom of it. the blown transistors are 104R5NT. ill check with the meter over the weekend
@@jamesbrokentech Ah great, if you have a scope, this will make like much easier, the 104R5NT seems to be rated at 100V and good for 120A so I reckon we can definitely confirm this is the DC side. Be good to hear back what you find, my guess is that the MOSFETS might have been killed by a dead driver, but it's only a guess at this stage. Incidentally, with the quality of construction with these things not always being stellar, if you find it IS the driver, it may be nothing more than a dry joint, cracked track that has effectively stopped the driver from working properly. Good luck and happy hunting!
