As for the original, it is now returned to the owner, who asked what the problem had been?
Not wishing to 'let a good crisis go to waste' I told him that it was his good fortune that I am somewhat of an electronics repair genius, and that the problem had been a design fault on the part of the Electrolux engineers.
I told him that one of the trans-flux, variable wing dipacitors was at fault, and that after reprogramming the microprocessor code, that the problem was now resolved.
It seemed a better response than to tell him that I absolutely no feckin idea what was going on...
The second unit only needed one charge in order to come back to life.
As for the original, it is now returned to the owner, who asked what the problem had been?
Not wishing to 'let a good crisis go to waste' I told him that it was his good fortune that I am somewhat of an electronics repair genius, and that the problem had been a design fault on the part of the Electrolux engineers.
I told him that one of the trans-flux, variable wing dipacitors was at fault, and that after reprogramming the microprocessor code, that the problem was now resolved.
It seemed a better response than to tell him that I absolutely no feckin idea what was going on...
did you connect the charger?
some battery protection circuits latch off untill you try to charge the battery
It lives!!
I had charged the new battery pack and it still didn't work, so bearing in mind what you said, with the motor disconnected and the board on the bench with only the batteries, I just kept charging it until the charge led went off, then unplugging the charger for a few hours.
Somewhere around the fifth charging cycle, it finally started putting the battery voltage out to the motor terminals.
It is now fully reassembled and working fine. Have run it through a couple of charging cycles and even hoovered the house. The fucker is fixed! One down, one to go...
Cannot thank you enough for that essential little insight.
so it's got conformal coating on it? bitches!
did you connect the charger?
some battery protection circuits latch off untill you try to charge the battery
clean the flux off ffs.
it's leading to q11
ultimatly it probably goes to the button so when you press the button it latches on and the microcontroller probably relaeses it after your done
try jumping the power across it to see if the mcu does stuff under poer.
btw - where is the charger/protection circuits?
Thanks to R_J for identifying the NG1N as a PNP although that hasn't helped me understand any more how the circuit should be working.
The circuit has a three pin HT7533, 3.3v voltage regulator which has zero volts on the 'voltage in' pin.
Following the circuit back it arrives at the emitter of the above mentioned PNP. I would have expected an NPN on that circuit.
I've never fully understood PNP transistors but had always been under the impression that the base must be negative to the emitter in order for the current to flow between the emitter and collector.
So how is a positive voltage supposed to arrive at the 'in' pin of the HT7533 if there is no voltage on the PNP?
I had thought that the button merely switched on the motor in the negative line, however I have just noticed that yes, one side is of the button at -ve potential, however the other side is at the battery positive of around 12v.
I wasn't expecting that
It might get to the point of just removing components and testing them off the board.
What this sounds like to me is that you either have broken trace or you have some bad soldering joint issues and if it is a double sided or more layers than that the trough hole pads might be broken
Here is what I would recommend take a magnifying glass and very carefully look at each and every soldering joint for separation ring or rings or very dull soldering joints and if you find any resolder them
I hope this helps you with your repair
Thanks for the suggestions but I don't see how it would apply to two different boards?
The Electrolux shop reckoned it was poor quality batteries although I've never seen this before. Other than that, I can't help but wonder if it wasn't some static charge?
Actually went to an Electrolux authorised repair centre this week and they neither sell replacement boards, nor do they repair them. They suggested that the boards were damaged by poor quality replacement batteries...
Anyways, these boards simply have to get fixed. No option...
Finally got a chance to have a closer look at the circuit, and there is an HT7533 3.3v sot89 voltage regulator (U2) which has zero volts on the 'in' pin.
Tracing the circuit back, it goes to the lower right hand side pin of an sot23 device (Q10) which is marked 'NG1N'. So far haven't managed to find out what kind of transistor this is?
The single pin of NG1N, then connects to an M7 diode (D6) which is connected to the board fuse.
A quick recap as to the situation. The owner bought three 18650 replacement cells and without any shorting, the unit stopped working.
The power from the battery comes into the board at CN4 (+ve) and CN6 (-ve).
The +ve line goes through a fuse and a couple of inductors straight to the motor via terminal FM+1.
The -ve side is switched through button (BT1) and a mosfet (Q18) before connecting to the motor negative terminal FM-1.
Obviously this FET isn't receiving any 'turn on' signal.
That comes from U1, an M2Q5VLC4 (MKE02Z32VLC4) microcontroller, however that isn't reveiving the 3.3v from the HT7533 due to the fact that nothing is coming from Q10 'NG1N'.
Need to find out what the NG1N is?
Attached Files
Last edited by Crystaleyes; 09-17-2023, 08:41 AM.
Reason: Because I keep getting logged out and have been unable to load the proper amount of photos.
Gonna do that, but am wondering why the same issue would pop up with two different boards? I thought that I was extra careful when installing the battery pack.
Anyways.. as mentioned, gonna get back on it tomorrow.
I'll remove one of the boards and post clear photos of every component.
It doesn't seem too complicated a pcb, in that it clearly has a charge control section and a motor control section.
The failure is that the N Channel enhancement FET isn't switching.
WHY that fecked up is another matter, but hopefully we can find out quickly
What this sounds like to me is that you either have broken trace or you have some bad soldering joint issues and if it is a double sided or more layers than that the trough hole pads might be broken
Here is what I would recommend take a magnifying glass and very carefully look at each and every soldering joint for separation ring or rings or very dull soldering joints and if you find any resolder them
I hope this helps you with your repair
Thanks fella.
I hope it helps too.
Having a day off it today but shall have a close look tomorrow
I had assumed that the first fella had perhaps shorted the batteries onto the board, but now I'm doubting that. I don't see how it can be static, as it worked fine after being soldered back together and the pcb securing pins only connect to plastic.
The only thing I can think of are that the new battery pack is somehow causing the damage. That is now two identical (working) pcb's that are now dead!
The battery pack consistes of three 18650 cells which are charged to around 12.5v although the charger is rated at 13.5v.
What this sounds like to me is that you either have broken trace or you have some bad soldering joint issues and if it is a double sided or more layers than that the trough hole pads might be broken
Here is what I would recommend take a magnifying glass and very carefully look at each and every soldering joint for separation ring or rings or very dull soldering joints and if you find any resolder them
The owner of the appliance was hassling so much that I picked up the same model for cheap just to use the pcb until this board got fixed.
I carefully disconnected the batteries before installing it and after carefully reconnecting the battery supply, gave it a quick test and it worked fine.
After screwing the pcb back down into the plastic frame however, the vacuum once again refused to work.
I had assumed that the first fella had perhaps shorted the batteries onto the board, but now I'm doubting that. I don't see how it can be static, as it worked fine after being soldered back together and the pcb securing pins only connect to plastic.
The only thing I can think of are that the new battery pack is somehow causing the damage. That is now two identical (working) pcb's that are now dead!
The battery pack consistes of three 18650 cells which are charged to around 12.5v although the charger is rated at 13.5v.
This is pissing me off now....
Fucking ball-ache!... How difficult can it be to connect a new battery pack?
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